├── .gitignore ├── Bitmap内存优化 ├── README ├── app ├── .gitignore ├── build.gradle ├── proguard-rules.pro └── src │ ├── androidTest │ └── java │ │ └── com │ │ └── wangshuai │ │ └── androidperformanceoptimation │ │ └── ExampleInstrumentedTest.java │ ├── main │ ├── AndroidManifest.xml │ ├── java │ │ └── com │ │ │ └── wangshuai │ │ │ └── androidperformanceoptimation │ │ │ ├── Consumer.java │ │ │ ├── MainActivity.java │ │ │ ├── MyApp.java │ │ │ ├── Person.java │ │ │ ├── Producer.java │ │ │ ├── ThreadTest.java │ │ │ ├── bitmapoptimation │ │ │ └── BitmapActivity.java │ │ │ ├── memoryleakage │ │ │ ├── CommonUtils.java │ │ │ └── MemoryLeakageActivity.java │ │ │ ├── network │ │ │ └── NetWorkActivity.java │ │ │ └── threadoptimation │ │ │ └── ThreadTest1.java │ └── res │ │ ├── layout │ │ ├── activity_bitmap.xml │ │ ├── activity_main.xml │ │ ├── activity_memory_leakage.xml │ │ └── activity_net_work.xml │ │ ├── mipmap-hdpi │ │ ├── ic_launcher.png │ │ └── ic_launcher_round.png │ │ ├── mipmap-mdpi │ │ ├── ic_launcher.png │ │ └── ic_launcher_round.png │ │ ├── mipmap-xhdpi │ │ ├── ic_launcher.png │ │ └── ic_launcher_round.png │ │ ├── mipmap-xxhdpi │ │ ├── ic_launcher.png │ │ └── ic_launcher_round.png │ │ ├── mipmap-xxxhdpi │ │ ├── ic_launcher.png │ │ └── ic_launcher_round.png │ │ └── values │ │ ├── colors.xml │ │ ├── strings.xml │ │ └── styles.xml │ └── test │ └── java │ └── com │ └── wangshuai │ └── androidperformanceoptimation │ └── ExampleUnitTest.java ├── build.gradle ├── gradle.properties ├── gradle └── wrapper │ ├── gradle-wrapper.jar │ └── gradle-wrapper.properties ├── gradlew ├── gradlew.bat ├── note ├── Java基本数据类型.txt ├── Java概述笔记.txt ├── android面试题.txt ├── 多线程.txt ├── 数据结构与算法.txt ├── 流与文件.txt ├── 网络编程.txt ├── 集合.txt └── 面向对象.txt ├── settings.gradle ├── 内存泄漏笔记 ├── 多线程优化 ├── 安装包优化 ├── 数据传输效率优化 └── 渲染机制以及优化 /.gitignore: -------------------------------------------------------------------------------- 1 | *.iml 2 | .gradle 3 | /local.properties 4 | /.idea/workspace.xml 5 | /.idea/libraries 6 | .DS_Store 7 | /build 8 | /captures 9 | .externalNativeBuild 10 | -------------------------------------------------------------------------------- /Bitmap内存优化: -------------------------------------------------------------------------------- 1 | #### 网络优化 2 | 3 | 1、请求缓存 4 | 5 | 三级缓存，外部缓存，LruCache，Sqlite缓存 6 | 7 | 8 | #### Bitmap优化 9 | 10 | 1）、图片压缩 11 | 12 | BitmapFactory Option参数： 13 | 14 | inDensity:bitmap的像素密度 15 | 16 | inTargetDensity:bitmap最终像素密度 17 | 18 | 质量压缩 19 | 20 | 尺寸压缩 21 | 22 | 采样率压缩 23 | 24 | #### 终极压缩方案 25 | 1、图像处理引擎 26 | 27 | android上使用的是skia引擎的阉割版（基于JPEG的图像引擎） 28 | 29 | 去掉了里面的一个算法--哈弗曼算法，采用定长编码算法，导致图片处理后的文件变大了 30 | 31 | 哈弗曼算法非常吃CPU，被迫使用了其他算法。但是解码还是保留了哈弗曼算法 32 | 33 | 2、实现方案 34 | 35 | 绕过安卓Bitmap API层，来自己实现编码，从而达到无损压缩数据的目的 36 | 37 | 用三位来表示一个字符信息，属于定长编码的最优 38 | 39 | 加权信息编码 40 | 41 | 哈弗曼编码：需要去扫描整个图片的信息（图片每一个像素包括ARGB），需要大量计算，非常耗CPU性能 42 | 43 | -------------------------------------------------------------------------------- /README: -------------------------------------------------------------------------------- 1 | ## android性能优化 2 | 1、内存泄漏 -------------------------------------------------------------------------------- /app/.gitignore: -------------------------------------------------------------------------------- 1 | /build 2 | -------------------------------------------------------------------------------- /app/build.gradle: -------------------------------------------------------------------------------- 1 | apply plugin: 'com.android.application' 2 | 3 | android { 4 | compileSdkVersion 25 5 | buildToolsVersion "26.0.0" 6 | defaultConfig { 7 | applicationId "com.wangshuai.androidperformanceoptimation" 8 | minSdkVersion 15 9 | targetSdkVersion 25 10 | versionCode 1 11 | versionName "1.0" 12 | testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" 13 | } 14 | buildTypes { 15 | release { 16 | minifyEnabled false 17 | proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' 18 | } 19 | } 20 | } 21 | 22 | dependencies { 23 | compile fileTree(dir: 'libs', include: ['*.jar']) 24 | androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', { 25 | exclude group: 'com.android.support', module: 'support-annotations' 26 | }) 27 | 28 | compile 'com.android.support:appcompat-v7:25.3.1' 29 | compile 'com.android.support.constraint:constraint-layout:1.0.2' 30 | testCompile 'junit:junit:4.12' 31 | debugCompile 'com.squareup.leakcanary:leakcanary-android:1.5.4' 32 | releaseCompile 'com.squareup.leakcanary:leakcanary-android-no-op:1.5.4' 33 | } 34 | -------------------------------------------------------------------------------- /app/proguard-rules.pro: -------------------------------------------------------------------------------- 1 | # Add project specific ProGuard rules here. 2 | # By default, the flags in this file are appended to flags specified 3 | # in D:\android-sdk-windows/tools/proguard/proguard-android.txt 4 | # You can edit the include path and order by changing the proguardFiles 5 | # directive in build.gradle. 6 | # 7 | # For more details, see 8 | # http://developer.android.com/guide/developing/tools/proguard.html 9 | 10 | # Add any project specific keep options here: 11 | 12 | # If your project uses WebView with JS, uncomment the following 13 | # and specify the fully qualified class name to the JavaScript interface 14 | # class: 15 | #-keepclassmembers class fqcn.of.javascript.interface.for.webview { 16 | # public *; 17 | #} 18 | 19 | # Uncomment this to preserve the line number information for 20 | # debugging stack traces. 21 | #-keepattributes SourceFile,LineNumberTable 22 | 23 | # If you keep the line number information, uncomment this to 24 | # hide the original source file name. 25 | #-renamesourcefileattribute SourceFile 26 | -------------------------------------------------------------------------------- /app/src/androidTest/java/com/wangshuai/androidperformanceoptimation/ExampleInstrumentedTest.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation; 2 | 3 | import android.content.Context; 4 | import android.support.test.InstrumentationRegistry; 5 | import android.support.test.runner.AndroidJUnit4; 6 | 7 | import org.junit.Test; 8 | import org.junit.runner.RunWith; 9 | 10 | import static org.junit.Assert.*; 11 | 12 | /** 13 | * Instrumentation test, which will execute on an Android device. 14 | * 15 | * @see Testing documentation 16 | */ 17 | @RunWith(AndroidJUnit4.class) 18 | public class ExampleInstrumentedTest { 19 | @Test 20 | public void useAppContext() throws Exception { 21 | // Context of the app under test. 22 | Context appContext = InstrumentationRegistry.getTargetContext(); 23 | 24 | assertEquals("com.wangshuai.androidperformanceoptimation", appContext.getPackageName()); 25 | } 26 | } 27 | -------------------------------------------------------------------------------- /app/src/main/AndroidManifest.xml: -------------------------------------------------------------------------------- 1 | 2 | 4 | 5 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/Consumer.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation; 2 | 3 | /** 4 | * Created by 王帅 on 2017/12/14. 5 | */ 6 | 7 | public class Consumer implements Runnable { 8 | 9 | Person person = null; 10 | 11 | public Consumer(Person person) { 12 | this.person = person; 13 | } 14 | 15 | @Override 16 | public void run() { 17 | while (true){ 18 | // System.out.println(person.getName()+"------"+person.getSex()); 19 | person.get(); 20 | } 21 | } 22 | } 23 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/MainActivity.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation; 2 | 3 | import android.content.Intent; 4 | import android.support.v7.app.AppCompatActivity; 5 | import android.os.Bundle; 6 | import android.support.v7.widget.AppCompatButton; 7 | import android.view.View; 8 | 9 | import com.wangshuai.androidperformanceoptimation.memoryleakage.MemoryLeakageActivity; 10 | 11 | public class MainActivity extends AppCompatActivity implements View.OnClickListener { 12 | 13 | private AppCompatButton btnMemoryLeakage; 14 | 15 | @Override 16 | protected void onCreate(Bundle savedInstanceState) { 17 | super.onCreate(savedInstanceState); 18 | setContentView(R.layout.activity_main); 19 | 20 | initViews(); 21 | } 22 | 23 | private void initViews() { 24 | btnMemoryLeakage = (AppCompatButton) findViewById(R.id.btn_memory_leakage); 25 | btnMemoryLeakage.setOnClickListener(this); 26 | } 27 | 28 | @Override 29 | public void onClick(View v) { 30 | switch (v.getId()){ 31 | case R.id.btn_memory_leakage: 32 | startActivity(new Intent(MainActivity.this, MemoryLeakageActivity.class)); 33 | break; 34 | } 35 | } 36 | } 37 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/MyApp.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation; 2 | 3 | import android.app.Application; 4 | 5 | import com.squareup.leakcanary.LeakCanary; 6 | import com.squareup.leakcanary.RefWatcher; 7 | 8 | /** 9 | * Created by 王帅 on 2017/12/12. 10 | */ 11 | 12 | public class MyApp extends Application { 13 | 14 | private RefWatcher refWatcher; 15 | 16 | @Override 17 | public void onCreate() { 18 | super.onCreate(); 19 | 20 | if (LeakCanary.isInAnalyzerProcess(this)) { 21 | // This process is dedicated to LeakCanary for heap analysis. 22 | // You should not init your app in this process. 23 | return; 24 | } 25 | refWatcher = LeakCanary.install(this); 26 | } 27 | 28 | // public static RefWatcher getRefWatcher(){ 29 | // return refWatcher; 30 | // } 31 | } 32 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/Person.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation; 2 | 3 | /** 4 | * Created by 王帅 on 2017/12/14. 5 | */ 6 | 7 | public class Person { 8 | private String name; 9 | private String sex; 10 | private boolean bFull = false;//是否完成赋值 11 | 12 | public String getName() { 13 | return name; 14 | } 15 | 16 | public void setName(String name) { 17 | this.name = name; 18 | } 19 | 20 | public String getSex() { 21 | return sex; 22 | } 23 | 24 | public void setSex(String sex) { 25 | this.sex = sex; 26 | } 27 | 28 | public synchronized void set(String name,String sex){ 29 | 30 | if (bFull){ 31 | try { 32 | wait(); 33 | } catch (InterruptedException e) { 34 | e.printStackTrace(); 35 | } 36 | } 37 | this.name = name; 38 | try { 39 | Thread.sleep(10); 40 | } catch (InterruptedException e) { 41 | e.printStackTrace(); 42 | } 43 | this.sex = sex; 44 | bFull = true; 45 | notify(); 46 | } 47 | 48 | public synchronized void get(){ 49 | if (!bFull){ 50 | try { 51 | wait(); 52 | } catch (InterruptedException e) { 53 | e.printStackTrace(); 54 | } 55 | } 56 | System.out.println(this.name+"-------------"+this.sex); 57 | bFull = false; 58 | notify(); 59 | } 60 | } 61 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/Producer.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation; 2 | 3 | /** 4 | * Created by 王帅 on 2017/12/14. 5 | */ 6 | 7 | public class Producer implements Runnable { 8 | 9 | Person person = null; 10 | 11 | public Producer(Person person) { 12 | this.person = person; 13 | } 14 | 15 | @Override 16 | public void run() { 17 | int i = 0; 18 | while (true){ 19 | if (i == 0){ 20 | // person.setName("张三"); 21 | // person.setSex("男"); 22 | person.set("张三","男"); 23 | }else { 24 | // person.setName("小红"); 25 | // person.setSex("女"); 26 | person.set("小红","女"); 27 | } 28 | i= (i+1)%2; 29 | } 30 | } 31 | } 32 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/ThreadTest.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation; 2 | 3 | /** 4 | * Created by 王帅 on 2017/12/14. 5 | */ 6 | 7 | public class ThreadTest { 8 | 9 | public static void main(String[] srgs){ 10 | Person person = new Person(); 11 | new Thread(new Producer(person)).start(); 12 | new Thread(new Consumer(person)).start(); 13 | } 14 | 15 | static class MyThread implements Runnable{ 16 | 17 | @Override 18 | public void run() { 19 | System.out.print("thread"); 20 | } 21 | } 22 | } 23 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/bitmapoptimation/BitmapActivity.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation.bitmapoptimation; 2 | 3 | import android.graphics.Bitmap; 4 | import android.graphics.BitmapFactory; 5 | import android.graphics.Canvas; 6 | import android.graphics.RectF; 7 | import android.os.Environment; 8 | import android.support.v7.app.AppCompatActivity; 9 | import android.os.Bundle; 10 | 11 | import com.wangshuai.androidperformanceoptimation.R; 12 | 13 | import java.io.ByteArrayOutputStream; 14 | import java.io.File; 15 | import java.io.FileNotFoundException; 16 | import java.io.FileOutputStream; 17 | import java.io.IOException; 18 | import java.util.HashMap; 19 | 20 | public class BitmapActivity extends AppCompatActivity { 21 | 22 | @Override 23 | protected void onCreate(Bundle savedInstanceState) { 24 | super.onCreate(savedInstanceState); 25 | setContentView(R.layout.activity_bitmap); 26 | 27 | } 28 | 29 | /** 30 | * 质量压缩：通过算法扣掉了图片中的一些某个些点附近相近的像素，达到降低质量文件大小的目的 31 | * 32 | * 他只能实现对file的影响，对加载这个图片出来的bitmap内存是无法节省的，还是那么大 33 | * 因为bitmap在内存中的大小是按照像素计算的，也就是width*height，对于质量压缩，并不会改变图片的真实的像素 34 | * 35 | * 使用场景：将图片压缩后保存到本地，或者将图片上传的服务器。 36 | */ 37 | private void qualityCompress(){ 38 | File imgFile = new File(Environment.getExternalStorageDirectory(),"img.png"); 39 | BitmapFactory.Options options = new BitmapFactory.Options(); 40 | Bitmap bitmap = BitmapFactory.decodeFile(imgFile.getAbsolutePath(),options); 41 | 42 | compressImageToFile(bitmap,new File("","质量压缩.jpeg")); 43 | } 44 | 45 | /** 46 | * 尺寸压缩: 47 | * 通过减少单位尺寸的像素值，真正意义上降低像素 48 | * 使用场景：缓存缩略图，头像 49 | * @param bitmap 50 | * @param file 51 | */ 52 | private void compressImageToFileBySize(Bitmap bitmap,File file){ 53 | //压缩尺寸倍数：值越大，图片的尺寸就越小 54 | int ratio = 4; 55 | Bitmap result = Bitmap.createBitmap(bitmap.getWidth()/ratio,bitmap.getHeight()/ratio,Bitmap.Config.ARGB_8888); 56 | 57 | Canvas canvas = new Canvas(result); 58 | RectF rect = new RectF(0,0,bitmap.getWidth()/ratio,bitmap.getHeight()/ratio); 59 | canvas.drawBitmap(bitmap,null,rect,null); 60 | 61 | ByteArrayOutputStream baos = new ByteArrayOutputStream(); 62 | result.compress(Bitmap.CompressFormat.JPEG,100,baos); 63 | 64 | try { 65 | FileOutputStream outputStream = new FileOutputStream(file); 66 | outputStream.write(baos.toByteArray()); 67 | outputStream.flush(); 68 | outputStream.close(); 69 | 70 | } catch (FileNotFoundException e) { 71 | e.printStackTrace(); 72 | }catch (IOException e) { 73 | e.printStackTrace(); 74 | } 75 | 76 | } 77 | 78 | /** 79 | * 采样率压缩： 80 | * 改变了图片的像素，他是通过先读取图片的边，然后在自己设定图片的边，然后根据设定，读取图片的像素。在读取的时候，并不是所有的像素都读取， 81 | * 而是由选择的。所以这种方式减少了像素的个数，能改变图片在内存中的占用大小。 82 | * 83 | * 采样率压缩，的的确确的改变了图片占用内存问题，但是由于像素改变，压缩容易造成失真问题。使用采样率压缩，不需要一开始把图片完全读取到内存， 84 | * 而是先读取图片的边，然后设置图片的尺寸，然后再根据尺寸，选择的读取像素。这种方法避免了一开始就吧图片读入内存而造成的oom异常。 85 | * @param filePath 86 | * @param file 87 | */ 88 | private void compreseImageToFileBySamplingRate(String filePath,File file){ 89 | //数值越高，图片像素越低，必须是2的倍数 90 | int inSampleSize = 8; 91 | BitmapFactory.Options options = new BitmapFactory.Options(); 92 | options.inJustDecodeBounds = false;//true:不会真正加载图片，二十得到图片的宽高信息 93 | options.inSampleSize = inSampleSize; 94 | Bitmap bitmap = BitmapFactory.decodeFile(filePath,options); 95 | 96 | } 97 | 98 | private void compressImageToFile(Bitmap bitmap, File file) { 99 | int quality = 50;//0-100 100 | ByteArrayOutputStream baos = new ByteArrayOutputStream(); 101 | bitmap.compress(Bitmap.CompressFormat.JPEG,quality,baos); 102 | try { 103 | FileOutputStream outputStream = new FileOutputStream(file); 104 | try { 105 | outputStream.write(baos.toByteArray()); 106 | outputStream.flush(); 107 | outputStream.close(); 108 | } catch (IOException e) { 109 | e.printStackTrace(); 110 | } 111 | 112 | } catch (FileNotFoundException e) { 113 | e.printStackTrace(); 114 | } 115 | } 116 | } 117 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/memoryleakage/CommonUtils.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation.memoryleakage; 2 | 3 | import android.content.Context; 4 | 5 | import java.util.ArrayList; 6 | 7 | /** 8 | * Created by 王帅 on 2017/12/11. 9 | */ 10 | 11 | public class CommonUtils { 12 | private Context context; 13 | private static CommonUtils instance; 14 | 15 | public CommonUtils(Context context) { 16 | this.context = context; 17 | } 18 | 19 | public static CommonUtils getInstance(Context context){ 20 | if (instance == null){ 21 | instance = new CommonUtils(context); 22 | } 23 | 24 | return instance; 25 | } 26 | 27 | /** 28 | * 正确用法： 29 | * 30 | * public CommonUtils(Context context){ 31 | * this.context = context.getApplicationContext(); 32 | * } 33 | * 保证context生命周期和Application的一样长 34 | */ 35 | } 36 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/memoryleakage/MemoryLeakageActivity.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation.memoryleakage; 2 | 3 | import android.os.Handler; 4 | import android.os.Message; 5 | import android.support.v7.app.AppCompatActivity; 6 | import android.os.Bundle; 7 | 8 | import com.wangshuai.androidperformanceoptimation.R; 9 | 10 | import java.lang.ref.WeakReference; 11 | 12 | /** 13 | * 内存泄漏 14 | */ 15 | public class MemoryLeakageActivity extends AppCompatActivity { 16 | 17 | @Override 18 | protected void onCreate(Bundle savedInstanceState) { 19 | super.onCreate(savedInstanceState); 20 | setContentView(R.layout.activity_memory_leakage); 21 | 22 | CommonUtils commonUtils = CommonUtils.getInstance(this);//单例导致内存泄漏例子 23 | 24 | // loadData(); 25 | // 26 | // mHandler.sendEmptyMessage(0); 27 | 28 | 29 | } 30 | 31 | /** 32 | * 错误写法（匿名内部类持外部引用造成内存泄漏问题） 33 | * 隐式持有Activity实例 34 | * 解决方案：将非静态内部类改为静态内部类（静态内部类不会隐式持有外部类） 35 | */ 36 | int a = 0; 37 | public void loadData(){ 38 | new Thread(new Runnable() { 39 | @Override 40 | public void run() { 41 | //进行操作 42 | int b = a; 43 | } 44 | }).start(); 45 | } 46 | 47 | //匿名内部类的实例，也会引用外部对象MainActivity.this 48 | private Handler mHandler = new Handler(){ 49 | @Override 50 | public void handleMessage(Message msg) { 51 | super.handleMessage(msg); 52 | // 53 | } 54 | }; 55 | 56 | //解决方案2：改成静态类,集成Handler 57 | private static class MyHandler extends Handler{ 58 | //如果需要持有一个外部类的强引用 59 | private WeakReference memoryReference;//设置软引用，当内存发生GC时候就会回收 60 | 61 | public MyHandler(MemoryLeakageActivity leakageActivity){ 62 | this.memoryReference = new WeakReference(leakageActivity); 63 | } 64 | 65 | @Override 66 | public void handleMessage(Message msg) { 67 | super.handleMessage(msg); 68 | // 69 | MemoryLeakageActivity memoryLeakageActivity = memoryReference.get(); 70 | if (memoryLeakageActivity == null || memoryLeakageActivity.isFinishing()){ 71 | return; 72 | } 73 | switch (msg.what){ 74 | case 0: 75 | break; 76 | } 77 | } 78 | } 79 | } 80 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/network/NetWorkActivity.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation.network; 2 | 3 | import android.net.http.HttpResponseCache; 4 | import android.support.v7.app.AppCompatActivity; 5 | import android.os.Bundle; 6 | 7 | import com.wangshuai.androidperformanceoptimation.R; 8 | 9 | import java.io.File; 10 | import java.io.IOException; 11 | import java.net.HttpURLConnection; 12 | import java.net.URL; 13 | 14 | public class NetWorkActivity extends AppCompatActivity { 15 | 16 | @Override 17 | protected void onCreate(Bundle savedInstanceState) { 18 | super.onCreate(savedInstanceState); 19 | setContentView(R.layout.activity_net_work); 20 | 21 | 22 | } 23 | 24 | private void openCache(){ 25 | 26 | try { 27 | //Android系统默认的HttpRe(网络请求相应缓存)是关闭的 28 | File cacheDir = new File(getCacheDir(),"http"); 29 | long maxSize = 10*1024*1024;//缓存大小，单位byte 30 | HttpResponseCache.install(cacheDir,maxSize); 31 | } catch (IOException e) { 32 | e.printStackTrace(); 33 | } 34 | } 35 | 36 | private void request(){ 37 | new Thread(new Runnable() { 38 | @Override 39 | public void run() { 40 | try { 41 | HttpURLConnection connection = (HttpURLConnection) new URL("").openConnection(); 42 | connection.setDoInput(true); 43 | 44 | } catch (IOException e) { 45 | e.printStackTrace(); 46 | } 47 | } 48 | }).start(); 49 | } 50 | } 51 | -------------------------------------------------------------------------------- /app/src/main/java/com/wangshuai/androidperformanceoptimation/threadoptimation/ThreadTest1.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation.threadoptimation; 2 | 3 | import android.os.AsyncTask; 4 | 5 | import java.util.ArrayList; 6 | import java.util.concurrent.Callable; 7 | import java.util.concurrent.ExecutionException; 8 | import java.util.concurrent.ExecutorService; 9 | import java.util.concurrent.Executors; 10 | import java.util.concurrent.FutureTask; 11 | 12 | /** 13 | * Created by 王帅 on 2017/12/14. 14 | */ 15 | 16 | public class ThreadTest1 { 17 | 18 | static class ProduceObject{ 19 | private String value = ""; 20 | } 21 | 22 | public static void main(String[] args){ 23 | // Handler 24 | Task work = new Task(); 25 | FutureTask futureTask = new FutureTask(work){ 26 | @Override 27 | protected void done() { 28 | 29 | } 30 | }; 31 | ExecutorService executorService = Executors.newCachedThreadPool(); 32 | executorService.execute(futureTask); 33 | 34 | try { 35 | futureTask.get(); 36 | } catch (InterruptedException e) { 37 | e.printStackTrace(); 38 | } catch (ExecutionException e) { 39 | e.printStackTrace(); 40 | } 41 | } 42 | 43 | static class Producer extends Thread{ 44 | @Override 45 | public void run() { 46 | while (true){ 47 | 48 | } 49 | } 50 | } 51 | 52 | static class Task implements Callable{ 53 | 54 | @Override 55 | public Integer call() throws Exception { 56 | return null; 57 | } 58 | } 59 | 60 | } 61 | -------------------------------------------------------------------------------- /app/src/main/res/layout/activity_bitmap.xml: -------------------------------------------------------------------------------- 1 | 2 | 8 | 9 | 10 | -------------------------------------------------------------------------------- /app/src/main/res/layout/activity_main.xml: -------------------------------------------------------------------------------- 1 | 2 | 9 | 10 | 15 | 16 | 17 | -------------------------------------------------------------------------------- /app/src/main/res/layout/activity_memory_leakage.xml: -------------------------------------------------------------------------------- 1 | 2 | 8 | 9 | 10 | -------------------------------------------------------------------------------- /app/src/main/res/layout/activity_net_work.xml: -------------------------------------------------------------------------------- 1 | 2 | 9 | 10 | 11 | -------------------------------------------------------------------------------- /app/src/main/res/mipmap-hdpi/ic_launcher.png: -------------------------------------------------------------------------------- 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#FF4081 6 | 7 | -------------------------------------------------------------------------------- /app/src/main/res/values/strings.xml: -------------------------------------------------------------------------------- 1 | 2 | AndroidPerformanceOptimation 3 | 内存泄漏 4 | 5 | -------------------------------------------------------------------------------- /app/src/main/res/values/styles.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 10 | 11 | 12 | -------------------------------------------------------------------------------- /app/src/test/java/com/wangshuai/androidperformanceoptimation/ExampleUnitTest.java: -------------------------------------------------------------------------------- 1 | package com.wangshuai.androidperformanceoptimation; 2 | 3 | import org.junit.Test; 4 | 5 | import static org.junit.Assert.*; 6 | 7 | /** 8 | * Example local unit test, which will execute on the development machine (host). 9 | * 10 | * @see Testing documentation 11 | */ 12 | public class ExampleUnitTest { 13 | @Test 14 | public void addition_isCorrect() throws Exception { 15 | assertEquals(4, 2 + 2); 16 | } 17 | } -------------------------------------------------------------------------------- /build.gradle: -------------------------------------------------------------------------------- 1 | // Top-level build file where you can add configuration options common to all sub-projects/modules. 2 | 3 | buildscript { 4 | repositories { 5 | jcenter() 6 | } 7 | dependencies { 8 | classpath 'com.android.tools.build:gradle:2.3.2' 9 | 10 | // NOTE: Do not place your application dependencies here; they belong 11 | // in the individual module build.gradle files 12 | } 13 | } 14 | 15 | allprojects { 16 | repositories { 17 | jcenter() 18 | } 19 | } 20 | 21 | task clean(type: Delete) { 22 | delete rootProject.buildDir 23 | } 24 | -------------------------------------------------------------------------------- /gradle.properties: -------------------------------------------------------------------------------- 1 | # Project-wide Gradle settings. 2 | 3 | # IDE (e.g. Android Studio) users: 4 | # Gradle settings configured through the IDE *will override* 5 | # any settings specified in this file. 6 | 7 | # For more details on how to configure your build environment visit 8 | # http://www.gradle.org/docs/current/userguide/build_environment.html 9 | 10 | # Specifies the JVM arguments used for the daemon process. 11 | # The setting is particularly useful for tweaking memory settings. 12 | org.gradle.jvmargs=-Xmx1536m 13 | 14 | # When configured, Gradle will run in incubating parallel mode. 15 | # This option should only be used with decoupled projects. More details, visit 16 | # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects 17 | # org.gradle.parallel=true 18 | -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.jar: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ws614054446/AndroidPerformanceOptimation/5d6a8414ff2b419c33a465a075fc8370ff34ea2d/gradle/wrapper/gradle-wrapper.jar -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.properties: -------------------------------------------------------------------------------- 1 | #Mon Dec 11 11:14:39 CST 2017 2 | distributionBase=GRADLE_USER_HOME 3 | distributionPath=wrapper/dists 4 | zipStoreBase=GRADLE_USER_HOME 5 | zipStorePath=wrapper/dists 6 | distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip 7 | -------------------------------------------------------------------------------- /gradlew: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env bash 2 | 3 | ############################################################################## 4 | ## 5 | ## Gradle start up script for UN*X 6 | ## 7 | ############################################################################## 8 | 9 | # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 10 | DEFAULT_JVM_OPTS="" 11 | 12 | APP_NAME="Gradle" 13 | APP_BASE_NAME=`basename "$0"` 14 | 15 | # Use the maximum available, or set MAX_FD != -1 to use that value. 16 | MAX_FD="maximum" 17 | 18 | warn ( ) { 19 | echo "$*" 20 | } 21 | 22 | die ( ) { 23 | echo 24 | echo "$*" 25 | echo 26 | exit 1 27 | } 28 | 29 | # OS specific support (must be 'true' or 'false'). 30 | cygwin=false 31 | msys=false 32 | darwin=false 33 | case "`uname`" in 34 | CYGWIN* ) 35 | cygwin=true 36 | ;; 37 | Darwin* ) 38 | darwin=true 39 | ;; 40 | MINGW* ) 41 | msys=true 42 | ;; 43 | esac 44 | 45 | # Attempt to set APP_HOME 46 | # Resolve links: $0 may be a link 47 | PRG="$0" 48 | # Need this for relative symlinks. 49 | while [ -h "$PRG" ] ; do 50 | ls=`ls -ld "$PRG"` 51 | link=`expr "$ls" : '.*-> \(.*\)$'` 52 | if expr "$link" : '/.*' > /dev/null; then 53 | PRG="$link" 54 | else 55 | PRG=`dirname "$PRG"`"/$link" 56 | fi 57 | done 58 | SAVED="`pwd`" 59 | cd "`dirname \"$PRG\"`/" >/dev/null 60 | APP_HOME="`pwd -P`" 61 | cd "$SAVED" >/dev/null 62 | 63 | CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar 64 | 65 | # Determine the Java command to use to start the JVM. 66 | if [ -n "$JAVA_HOME" ] ; then 67 | if [ -x "$JAVA_HOME/jre/sh/java" ] ; then 68 | # IBM's JDK on AIX uses strange locations for the executables 69 | JAVACMD="$JAVA_HOME/jre/sh/java" 70 | else 71 | JAVACMD="$JAVA_HOME/bin/java" 72 | fi 73 | if [ ! -x "$JAVACMD" ] ; then 74 | die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME 75 | 76 | Please set the JAVA_HOME variable in your environment to match the 77 | location of your Java installation." 78 | fi 79 | else 80 | JAVACMD="java" 81 | which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 82 | 83 | Please set the JAVA_HOME variable in your environment to match the 84 | location of your Java installation." 85 | fi 86 | 87 | # Increase the maximum file descriptors if we can. 88 | if [ "$cygwin" = "false" -a "$darwin" = "false" ] ; then 89 | MAX_FD_LIMIT=`ulimit -H -n` 90 | if [ $? -eq 0 ] ; then 91 | if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then 92 | MAX_FD="$MAX_FD_LIMIT" 93 | fi 94 | ulimit -n $MAX_FD 95 | if [ $? -ne 0 ] ; then 96 | warn "Could not set maximum file descriptor limit: $MAX_FD" 97 | fi 98 | else 99 | warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT" 100 | fi 101 | fi 102 | 103 | # For Darwin, add options to specify how the application appears in the dock 104 | if $darwin; then 105 | GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\"" 106 | fi 107 | 108 | # For Cygwin, switch paths to Windows format before running java 109 | if $cygwin ; then 110 | APP_HOME=`cygpath --path --mixed "$APP_HOME"` 111 | CLASSPATH=`cygpath --path --mixed "$CLASSPATH"` 112 | JAVACMD=`cygpath --unix "$JAVACMD"` 113 | 114 | # We build the pattern for arguments to be converted via cygpath 115 | ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null` 116 | SEP="" 117 | for dir in $ROOTDIRSRAW ; do 118 | ROOTDIRS="$ROOTDIRS$SEP$dir" 119 | SEP="|" 120 | done 121 | OURCYGPATTERN="(^($ROOTDIRS))" 122 | # Add a user-defined pattern to the cygpath arguments 123 | if [ "$GRADLE_CYGPATTERN" != "" ] ; then 124 | OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)" 125 | fi 126 | # Now convert the arguments - kludge to limit ourselves to /bin/sh 127 | i=0 128 | for arg in "$@" ; do 129 | CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -` 130 | CHECK2=`echo "$arg"|egrep -c "^-"` ### Determine if an option 131 | 132 | if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then ### Added a condition 133 | eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"` 134 | else 135 | eval `echo args$i`="\"$arg\"" 136 | fi 137 | i=$((i+1)) 138 | done 139 | case $i in 140 | (0) set -- ;; 141 | (1) set -- "$args0" ;; 142 | (2) set -- "$args0" "$args1" ;; 143 | (3) set -- "$args0" "$args1" "$args2" ;; 144 | (4) set -- "$args0" "$args1" "$args2" "$args3" ;; 145 | (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;; 146 | (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;; 147 | (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;; 148 | (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;; 149 | (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;; 150 | esac 151 | fi 152 | 153 | # Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules 154 | function splitJvmOpts() { 155 | JVM_OPTS=("$@") 156 | } 157 | eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS 158 | JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME" 159 | 160 | exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@" 161 | -------------------------------------------------------------------------------- /gradlew.bat: -------------------------------------------------------------------------------- 1 | @if "%DEBUG%" == "" @echo off 2 | @rem ########################################################################## 3 | @rem 4 | @rem Gradle startup script for Windows 5 | @rem 6 | @rem ########################################################################## 7 | 8 | @rem Set local scope for the variables with windows NT shell 9 | if "%OS%"=="Windows_NT" setlocal 10 | 11 | @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 12 | set DEFAULT_JVM_OPTS= 13 | 14 | set DIRNAME=%~dp0 15 | if "%DIRNAME%" == "" set DIRNAME=. 16 | set APP_BASE_NAME=%~n0 17 | set APP_HOME=%DIRNAME% 18 | 19 | @rem Find java.exe 20 | if defined JAVA_HOME goto findJavaFromJavaHome 21 | 22 | set JAVA_EXE=java.exe 23 | %JAVA_EXE% -version >NUL 2>&1 24 | if "%ERRORLEVEL%" == "0" goto init 25 | 26 | echo. 27 | echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 28 | echo. 29 | echo Please set the JAVA_HOME variable in your environment to match the 30 | echo location of your Java installation. 31 | 32 | goto fail 33 | 34 | :findJavaFromJavaHome 35 | set JAVA_HOME=%JAVA_HOME:"=% 36 | set JAVA_EXE=%JAVA_HOME%/bin/java.exe 37 | 38 | if exist "%JAVA_EXE%" goto init 39 | 40 | echo. 41 | echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 42 | echo. 43 | echo Please set the JAVA_HOME variable in your environment to match the 44 | echo location of your Java installation. 45 | 46 | goto fail 47 | 48 | :init 49 | @rem Get command-line arguments, handling Windowz variants 50 | 51 | if not "%OS%" == "Windows_NT" goto win9xME_args 52 | if "%@eval[2+2]" == "4" goto 4NT_args 53 | 54 | :win9xME_args 55 | @rem Slurp the command line arguments. 56 | set CMD_LINE_ARGS= 57 | set _SKIP=2 58 | 59 | :win9xME_args_slurp 60 | if "x%~1" == "x" goto execute 61 | 62 | set CMD_LINE_ARGS=%* 63 | goto execute 64 | 65 | :4NT_args 66 | @rem Get arguments from the 4NT Shell from JP Software 67 | set CMD_LINE_ARGS=%$ 68 | 69 | :execute 70 | @rem Setup the command line 71 | 72 | set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar 73 | 74 | @rem Execute Gradle 75 | "%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS% 76 | 77 | :end 78 | @rem End local scope for the variables with windows NT shell 79 | if "%ERRORLEVEL%"=="0" goto mainEnd 80 | 81 | :fail 82 | rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of 83 | rem the _cmd.exe /c_ return code! 84 | if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1 85 | exit /b 1 86 | 87 | :mainEnd 88 | if "%OS%"=="Windows_NT" endlocal 89 | 90 | :omega 91 | -------------------------------------------------------------------------------- /note/Java基本数据类型.txt: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ws614054446/AndroidPerformanceOptimation/5d6a8414ff2b419c33a465a075fc8370ff34ea2d/note/Java基本数据类型.txt -------------------------------------------------------------------------------- /note/Java概述笔记.txt: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ws614054446/AndroidPerformanceOptimation/5d6a8414ff2b419c33a465a075fc8370ff34ea2d/note/Java概述笔记.txt 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/note/面向对象.txt: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ws614054446/AndroidPerformanceOptimation/5d6a8414ff2b419c33a465a075fc8370ff34ea2d/note/面向对象.txt -------------------------------------------------------------------------------- /settings.gradle: -------------------------------------------------------------------------------- 1 | include ':app' 2 | -------------------------------------------------------------------------------- /内存泄漏笔记: -------------------------------------------------------------------------------- 1 | #### 1、什么是内存泄漏 2 | 当一个对象已经不需要使用了，本该被回收时，但是另外一个使用的对象持有它的应引用，从而导致对象不能被回收。这种导致了本该被回收的对象不能被回收而停留在堆内存中，就叫内存泄漏。 3 | (GC只有在对象不再有任何的引用的时候才会进行回收) 4 | 5 | 内存溢出（OOM）：当应用占用的heap资源超过了Dalvik虚拟机分配的内存就会内存溢出。 6 | 当内存泄漏过多的时候，再加上应用本身占用的内存，最终就会导致内存溢出。 7 | #### 2、内存分配的几种策略 8 | - 静态的：内存在程序编译的时候就已经分配好了。这块的内存在程序整个运行期间都一直存在。 9 | 10 | - 栈式的：在执行函数时，函数的一些内部变量的存储都可以放在栈上创建，函数执行结束的时候， 11 | 这些存储单元就会自动被释放掉。 12 | 13 | - 堆式的：也叫动态分配内存。如创建数组和对象。 14 | 15 | - 常量池：在编译期被确定，并被保存在已编译的.class文件中的一些数据。 16 | 17 | 栈的优势是，存取速度比堆要快，仅次于寄存器，栈数据可以共享。但缺点是，存在栈中的数据大小与生存期必须是确定的。 18 | 19 | #### 3、对象引用的四种级别 20 | - 强引用（StrongReference）：GC绝不会回收它。当内存空间不足，JVM宁愿抛出OutOfMemoryError错误，使程序异常终止，也不会靠随意回收具有强引用的对象来解决内存不足问题。 21 | - 软引用（SoftReference）：如果内存空间足够，GC就不会回收它，如果内存空间不足了，就会回收这些对象的内存。只要GC没有回收它，该对象就可以被程序使用。软引用可用来实现内存敏感的高速缓存。 22 | - 弱引用（WeakReference）：弱引用与软引用的区别在于：只具有弱引用的对象拥有更短暂的生命周期。在GC扫描它所管辖的内存区域的过程中，一旦发现了只具有弱引用的对象，不管当前内存空间足够与否，都会回收它的内存。 23 | - 虚引用（PhatomReference）：虚引用并不会决定对象的生命周期。如果一个对象仅持有虚引用，那么它就和没有任何引用一样，在任何时候都可能被垃圾回收。虚引用必须和引用队列（ReferenceQueue）联合使用。 24 | 25 | 开发时，为了防治内存溢出，处理一些比较占用内存大并且生命周期长的对象的时候，可以尽量使用软引用和弱引用。 26 | 27 | #### 使用MAT（Memory Analyzer Tool） 28 | 29 | [MAT下载地址](http://www.eclipse.org/mat/downloads.php) 30 | 31 | 查看内存泄漏的类，查看其被哪些类引用。 32 | 33 | #### 如何找到项目中存在的内存泄漏 34 | 1、确定是否存在内存泄漏 35 | 1）、Android Monitors分析内存 36 | 记录动作发生之前GC完的内存大小，然后记录动作发生之后GC完后的内存大小，两个比较大小，如果内存变大的话，则可能存在内存泄漏。 37 | 38 | 使用MAT内存分析工具 39 | MAT分析heap的总内存占用大小来初步判断是否存在内存泄漏 40 | Heap视图中有一个Type叫data object,即数据对象，也就是我们程序中大量存在的类型的对象。 41 | 在data object中有一项“Total Size”，其值就是当前进程中所有Java数据对象的内存总来过。 42 | 进行操作前和操作后的内存的大小比较。正常情况下Total Size值都会稳定在一个有限的范围内， 43 | 也就是没有内存泄漏。如果值不断增大，则可以初步判断这个操作导致了内存泄漏。 44 | 45 | 2、先找到怀疑对象（哪些对象属于泄漏的） 46 | MAT对比操作前后的hprof来定位内存泄漏了什么数据对象。（这样做可以排除一些对象，不用后面去查看所有被引用的对象是否有嫌疑）。 47 | 快速定位到操作前后所持有的对象哪些是增加了的（GC后还是比之前多出来的对象就可能是内存泄漏的源头）。 48 | 技巧：Histogram中还可以对对象进行Grpup By Package更方便查看自己包里的对象信息。 49 | 50 | 3、MAT分析hprof来定位内存泄漏的原因（哪个对象持有了上面怀疑出来的发生泄漏的对象） 51 | 52 | 1）Dump出内存泄露“当时”的内存镜像hprof，分析怀疑泄露的类； 53 | 54 | 2）把上面2得出的这些嫌疑犯一个一个排查个遍。 55 | 56 | 步骤： 57 | (1)进入Histogram，过滤出某一个嫌疑对象类 58 | 59 | (2)然后分析持有此类对象引用的外部对象（在该类上面点击右键List Objects--->with incoming references） 60 | 61 | (3)再过滤掉一些弱引用、软引用、虚引用，因为它们迟早可以被GC干掉不属于内存泄露 62 | (在类上面点击右键Merge Shortest Paths to GC Roots--->exclude all phantom/soft etc.references) 63 | (4)逐个分析每个对象的GC路径是否正常 64 | 65 | ###### 退出app后，GC后，产看系统进程里的所有的View和Activity对象是否为0， 66 | Android Monitors--System Information--Memory Usage查看 67 | 68 | #### 常见的内存泄漏 69 | 1、静态变量引起的内存泄漏 70 | 71 | 2、非静态内部类引起内存泄漏（包括匿名内部类） 72 | ``` 73 | /** 74 | * 错误写法（匿名内部类持外部引用造成内存泄漏问题） 75 | * 隐式持有Activity实例 76 | * 解决方案：将非静态内部类改为静态内部类（静态内部类不会隐式持有外部类） 77 | */ 78 | int a = 0; 79 | public void loadData(){ 80 | new Thread(new Runnable() { 81 | @Override 82 | public void run() { 83 | //进行操作 84 | int b = a; 85 | } 86 | }).start(); 87 | } 88 | 89 | //匿名内部类的实例，也会引用外部对象MainActivity.this 90 | //解决方案：改成静态的 91 | private Handler mHandler = new Handler(){ 92 | @Override 93 | public void handleMessage(Message msg) { 94 | super.handleMessage(msg); 95 | // 96 | } 97 | }; 98 | 99 | //解决方案2：改成静态类,集成Handler 100 | private static class MyHandler extends Handler{ 101 | //如果需要持有一个外部类的强引用 102 | 103 | 104 | 105 | @Override 106 | public void handleMessage(Message msg) { 107 | super.handleMessage(msg); 108 | // 109 | } 110 | } 111 | 112 | ``` 113 | 114 | 115 | 3、资源未关闭引起的内存泄漏情况： 116 | 117 | 比如：BroadCastReceiver,Cursor,Bitmap,IO流,自定义属性（attr.recycle） 118 | 119 | 4、无限循环 120 | 121 | 在onDestory中停止 122 | 123 | 5、WebView内存泄漏 124 | 解决办法是通过把使用了WebView的Activity(或者Service)放在单独的进程里。 125 | 然后在检测到应用占用内存过大有可能被系统干掉或者它所在的Activity(或者Service)结束后， 126 | 调用android.os.Process.killProcess(android.os.Process.myPid());，主动Kill掉进程。 127 | 由于系统的内存分配是以进程为准的，进程关闭后，系统会自动回收所有内存。 128 | ``` 129 | 132 | ``` 133 | 134 | 135 | #### 性能优化工具 136 | 137 | 常用的有：MAT,Memory Monitor,HeapTool,Allaction Tracking,LeakCanary,Lint工具 138 | 139 | 1、Allaction Tracking 140 | 141 | 追踪内存分配信息。可以直观地看到某个操作的内存是如何一步一步地分配的 142 | 143 | 144 | 2、LeakCanary 145 | 146 | [github地址](https://github.com/square/leakcanary) 147 | 148 | 可以直接在手机端查看内存泄漏的工具。 149 | 150 | 3、Lint工具 151 | 152 | 可以检测常见的内存泄漏 153 | 154 | 可以检测资源文件是否用到 155 | 156 | 可以检测代码规范 157 | 158 | 可以检测android版本安全问题 159 | 160 | 没用的导包 161 | 162 | 可能的bug 163 | -------------------------------------------------------------------------------- /多线程优化: -------------------------------------------------------------------------------- 1 | volatile//线程操作变量可见 2 | 3 | #### AsyncTask源码分析 4 | 5 | public AsyncTask() { 6 | mWorker = new WorkerRunnable() { 7 | public Result call() throws Exception { 8 | mTaskInvoked.set(true); 9 | Result result = null; 10 | try { 11 | Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND); 12 | //noinspection unchecked 13 | result = doInBackground(mParams); 14 | Binder.flushPendingCommands(); 15 | } catch (Throwable tr) { 16 | mCancelled.set(true); 17 | throw tr; 18 | } finally { 19 | postResult(result); 20 | } 21 | return result; 22 | } 23 | }; 24 | 25 | mFuture = new FutureTask(mWorker) { 26 | @Override 27 | protected void done() { 28 | try { 29 | postResultIfNotInvoked(get()); 30 | } catch (InterruptedException e) { 31 | android.util.Log.w(LOG_TAG, e); 32 | } catch (ExecutionException e) { 33 | throw new RuntimeException("An error occurred while executing doInBackground()", 34 | e.getCause()); 35 | } catch (CancellationException e) { 36 | postResultIfNotInvoked(null); 37 | } 38 | } 39 | }; 40 | } 41 | 42 | 43 | WorkerRunnable实现Callable,传给FutureTask;FutureTask由线程池执行这个异步任务。 44 | 45 | WorkerRunnable中call方法执行doInBackground() 46 | 47 | FutureTask中get()方法获取子线程中的返回值，等待异步任务执行完毕。 48 | 49 | 当子线程执行完毕之后，执行done()方法，通过Handler发送信息将返回值发送到主线程。 50 | 51 | 所有异步任务都是通过excute执行FutureTask； 52 | 53 | SerialExecutor implements Executor 54 | 55 | exec.execute(mFuture); 56 | 57 | 58 | FutureTask异步操作提供了便利性： 59 | 60 | 1、获取异步任务的返回值 61 | 62 | 2、监听异步任务的执行完毕 63 | 64 | 3、取消异步任务 65 | 66 | static { 67 | ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor( 68 | CORE_POOL_SIZE, MAXIMUM_POOL_SIZE, KEEP_ALIVE_SECONDS, TimeUnit.SECONDS, 69 | sPoolWorkQueue, sThreadFactory); 70 | threadPoolExecutor.allowCoreThreadTimeOut(true); 71 | THREAD_POOL_EXECUTOR = threadPoolExecutor; 72 | } 73 | 74 | CORE_POOL_SIZE:核心线程数 75 | 76 | MAXIMUM_POOL_SIZE：最大线程数 77 | 78 | KEEP_ALIVE_SECONDS：闲置回收 79 | 80 | TimeUnit.SECONDS：时间单位 81 | 82 | sPoolWorkQueue：异步任务队列 83 | 84 | sThreadFactory：线程工厂 85 | 86 | 添加到线程池是串行，添加到线程池后执行是并行； 87 | 88 | 1、线程池容量不够抛出异常； 89 | 2、内存泄漏； 90 | 3、 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | 101 | 102 | 103 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 | 112 | 113 | 114 | 115 | 116 | 117 | -------------------------------------------------------------------------------- /安装包优化: -------------------------------------------------------------------------------- 1 | #### 图片压缩 2 | 1、svg图片：一些图片的描述，牺牲CPU的计算能力，节省空间 3 | 4 | 使用原则：简单的图标 5 | 6 | 2、webp图片 7 | 8 | Google提倡使用，保存图片比较小。webp的无损压缩比PNG文件小45%左右 9 | 10 | 缺点： 11 | 12 | 相比加载PNG要慢很多，但是配置比较高。 13 | 14 | http://isparta.github.io/ 15 | 16 | 17 | #### 资源动态加载 18 | 19 | 比如：表情，换肤；动态下载的资源；一些模块的插件化。 20 | 21 | #### Lint工具建议优化的点 22 | 23 | 检测没有用的布局，未使用到的布局等 24 | 25 | 26 | #### Proguard混淆 27 | 28 | 能删除注释和不用的代码；可以将Java文件名或者方法名改成短名 29 | 30 | 31 | #### 7zZip极限压缩 32 | 33 | 在常规的安装包优化之外继续压缩（资源文件再压缩） 34 | 35 | 实现将res/drawable/ic_lanchuer.png改成a.png 36 | 37 | drawable文件名字，string文件的名字。layout的名字 38 | 39 | 可以将res/drawable/ic_lanchuer.png改成r/d/a.png 40 | 41 | 解决方法： 42 | 43 | 读取resources.arsc二进制文件，然后修改某一段的字节 44 | 45 | 有一段叫做res/drawable/ic_lanchuer.png在自己的数组当中的第800位-810位 46 | 将这一段第800位-810位替换成r/d/a.png的字节码 -------------------------------------------------------------------------------- /数据传输效率优化: -------------------------------------------------------------------------------- 1 | #### 概述 2 | JSON是最常用的数据序列化技术。JSON的可读性很强，但是序列化和反序列化性能是最差 3 | 的。解析的时候，JSON解析器首先需要在内存中初始化一个对应的数据结构，解析的过程中， 4 | 要产生大量的临时变量，造成JAVA虚拟机的GC和内存抖动。 5 | 6 | #### FlatBuffers 7 | 基本原理： 8 | 9 | 把结构化的对象，用一个扁平化（Flat）的缓冲区，简单的来说就是把对象数据， 10 | 保存在一个一维数组中。FlatBuffers通过自己分配和管理对象的存储，使对象在内存中就是 11 | 线性结构化的，可以直接把内存内容保存或者发送出去。解析数据只需要把 12 | byte数组加载到内存中，不需要任何解析，也不产生任何中间变量。 13 | 14 | 优点： 15 | 16 | 1、直接读取序列化数据，不需要解析。 17 | 18 | 2、高效的内存使用和速度：不需要额外的内存，几乎接近原始数据在内存中的大小 19 | 20 | 3、灵活：数据能够向前后兼容，并且能够灵活控制你的数据结构 21 | 22 | 5、强类型，易于使用，跨平台，几乎与语言无关 23 | 24 | 缺点： 25 | 26 | 1、需要生成代码，对代码有侵入性 27 | 28 | 2、数据序列化没有可读性，不方便Debug； 29 | 30 | 3、构建FlatBuffers对象比较麻烦，不直观，特别是如果对象比较复杂的情况下需要写 31 | 大段的代码； 32 | 33 | 4、数据所有内容需要schema严格定义，灵活性不如JSON -------------------------------------------------------------------------------- /渲染机制以及优化: -------------------------------------------------------------------------------- 1 | #### 卡顿是如何造成的 2 | 3 | 1、外部原因 4 | 5 | 在主线程里进行网络访问或者IO操作 6 | 7 | 2、View本身的卡顿 8 | 9 | 可以使用Allocation Tracing来定位大致的情况 10 | 然后可以使用TraceView来确定详细的问题所在 11 | 12 | #### 内存抖动 13 | 14 | 在短时间内分配大量内存并经行大量GC操作 15 | 16 | #### 渲染机制 17 | 18 | 屏幕理想帧率：60fps：每秒绘制帧数； 19 | 20 | 在60fps帧率下，每一秒只能停留16ms； 21 | 22 | VSYNC(垂直刷新/绘制)： 23 | - Refresh Rate:屏幕在一秒内刷新屏幕的次数--由硬件参数决定，比如60Hz 24 | - Frame Rate:GPU一秒内绘制操作的帧数，如：60fps 25 | 26 | GPU刷新：GPU帮助我们将UI组件等计算成纹理Texture和三维图形Polygons,同时 27 | 会使用OpenGL--会将纹理和三维图形缓存在GPU内存里面 28 | 29 | 在渲染机制里比较耗时的操作： 30 | 31 | 1、cpu计算时间： 32 | 从减轻加工View对象成Polyons和Texture下手优化。很多无用的View不会显示在屏幕上面， 33 | 一旦触发测量和布局操作，就会拖累应用的性能表现。 34 | 35 | 2、CPU将计算好的Texture和Polygons传递到GPU 36 | 37 | OpenGL ES API允许数据到GPU后，可以对数据进行保存，做了缓存 38 | 39 | 3、GPU进行栅格化 40 | 41 | 渲染性能优化就是尽可能地上传数据到GPU，然后尽可能长地在不修改的情况下保存数据。 42 | 43 | #### 渲染优化 44 | 45 | 1、尽可能避免过度绘制 46 | - 背景经常造成过度绘制： 47 | 由于背景设置了颜色，同时又用到了MeterialDesign的主题会默认给一个背景（将主题添加的背景去掉） 48 | getWindow().setBackgroundDrawable(null) 49 | - 自定义控件如何处理过度绘制： 50 | 通过裁剪来处理 51 | 52 | - 布局优化： 53 | 54 | 1）、当我们的布局是用FrameLayout的时候，可以改成merge 55 | 56 | 可以避免自己的帧布局和系统的ContentFrameLayout布局重叠造成重复计算（measure和layout） 57 | 58 | 2）、 59 | 60 | #### Hierarchy View 61 | 62 | Android Device Monitor 63 | 64 | 可以查看页面布局层级以及查看每个布局的measure,layout,draw的时间。 65 | 三个原点分别代表测量，布局，绘制这三个阶段的性能表现： 66 | 67 | 1）、绿色：渲染的管道阶段，这个视图的渲染速度至少快于一半的其他视图 68 | 69 | 2）、黄色：渲染速度比较慢的50% 70 | 71 | 3）、红色：渲染速度非常慢 72 | 73 | 74 | 75 | --------------------------------------------------------------------------------