├── .gitignore ├── .idea ├── .name ├── compiler.xml ├── copyright │ └── profiles_settings.xml ├── encodings.xml ├── gradle.xml ├── misc.xml ├── modules.xml ├── runConfigurations.xml └── vcs.xml ├── LICENSE ├── README.md ├── app ├── .gitignore ├── build.gradle ├── proguard-rules.pro └── src │ ├── androidTest │ └── java │ │ └── com │ │ └── thinkcool │ │ └── efficientloadingpicture │ │ └── ApplicationTest.java │ ├── main │ ├── AndroidManifest.xml │ ├── java │ │ └── com │ │ │ └── thinkcool │ │ │ └── efficientloadingpicture │ │ │ ├── Activity │ │ │ └── MainActivity.java │ │ │ └── Utils │ │ │ └── BitmapUtils.java │ └── res │ │ ├── drawable │ │ ├── res_img.jpg │ │ └── res_photo.png │ │ ├── layout │ │ └── activity_main.xml │ │ ├── menu │ │ └── menu_main.xml │ │ ├── mipmap-hdpi │ │ └── ic_launcher.png │ │ ├── mipmap-mdpi │ │ └── ic_launcher.png │ │ ├── mipmap-xhdpi │ │ └── ic_launcher.png │ │ ├── mipmap-xxhdpi │ │ └── ic_launcher.png │ │ ├── mipmap-xxxhdpi │ │ └── ic_launcher.png │ │ ├── values-v21 │ │ └── styles.xml │ │ ├── values-w820dp │ │ └── dimens.xml │ │ └── values │ │ ├── colors.xml │ │ ├── dimens.xml │ │ ├── strings.xml │ │ └── styles.xml │ └── test │ └── java │ └── com │ └── thinkcool │ └── efficientloadingpicture │ └── ExampleUnitTest.java ├── build.gradle ├── gradle.properties ├── gradle └── wrapper │ ├── gradle-wrapper.jar │ └── gradle-wrapper.properties ├── gradlew ├── gradlew.bat └── settings.gradle /.gitignore: -------------------------------------------------------------------------------- 1 | <<<<<<< HEAD 2 | *.iml 3 | .gradle 4 | /local.properties 5 | /.idea/workspace.xml 6 | /.idea/libraries 7 | .DS_Store 8 | /build 9 | /captures 10 | ======= 11 | # Built application files 12 | *.apk 13 | *.ap_ 14 | 15 | # Files for the Dalvik VM 16 | *.dex 17 | 18 | # Java class files 19 | *.class 20 | 21 | # Generated files 22 | bin/ 23 | gen/ 24 | 25 | # Gradle files 26 | .gradle/ 27 | build/ 28 | /*/build/ 29 | 30 | # Local configuration file (sdk path, etc) 31 | local.properties 32 | 33 | # Proguard folder generated by Eclipse 34 | proguard/ 35 | 36 | # Log Files 37 | *.log 38 | >>>>>>> c61417835c5499a1b8301b4ea4fe74913e344699 39 | -------------------------------------------------------------------------------- /.idea/.name: -------------------------------------------------------------------------------- 1 | EfficientLoadingPicture -------------------------------------------------------------------------------- /.idea/compiler.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | -------------------------------------------------------------------------------- /.idea/copyright/profiles_settings.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | -------------------------------------------------------------------------------- /.idea/encodings.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | -------------------------------------------------------------------------------- /.idea/gradle.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 18 | 19 | -------------------------------------------------------------------------------- /.idea/misc.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 19 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 46 | -------------------------------------------------------------------------------- /.idea/modules.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | -------------------------------------------------------------------------------- /.idea/runConfigurations.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 11 | 12 | -------------------------------------------------------------------------------- /.idea/vcs.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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22 | options.inJustDecodeBounds = true; 23 | BitmapFactory.decodeFile(file_path, options); 24 | options.inSampleSize = getFitInSampleSize(width, height, options); 25 | options.inJustDecodeBounds = false; 26 | return BitmapFactory.decodeFile(file_path, options); 27 | } 28 | public static int getFitInSampleSize(int reqWidth, int reqHeight, BitmapFactory.Options options) { 29 | int inSampleSize = 1; 30 | if (options.outWidth > reqWidth || options.outHeight > reqHeight) { 31 | int widthRatio = Math.round((float) options.outWidth / (float) reqWidth); 32 | int heightRatio = Math.round((float) options.outHeight / (float) reqHeight); 33 | inSampleSize = Math.min(widthRatio, heightRatio); 34 | } 35 | return inSampleSize; 36 | } 37 | ``` 38 |        BitmapFactory提供了BitmapFactory.Option，用于设置图像相关的参数，在调用decode的时候我们可以将其传入来对图像进行相关设置。这里我们主要介绍option里的两个成员:inJustDecodeBounds(Boolean类型) 和inSampleSize(int类型)。 39 |        inJustDecodeBounds :如果设置为true则表示decode函数不会生成bitmap对象，仅是将图像相关的参数填充到option对象里，这样我们就可以在不生成bitmap而获取到图像的相关参数了。 40 |        inSampleSize:表示对图像像素的缩放比例。假设值为2，表示decode后的图像的像素为原图像的1/2。在上面的代码里我们封装了个简单的getFitInSampleSize函数（将传入的option.outWidth和option.outHeight与控件的width和height对应相除再取其中较小的值）来获取一个适当的inSampleSize。 41 |        在设置了option的inSampleSize后我们将inJustDecodeBounds设置为false再次调用decode函数时就能生成bitmap了。 42 | 43 | 这里需要注意的是如果我们decodeFile解析的文件是外部存储里的文件,我们需要在Manifists加上文件的读写权限,不然获取的bitmap会为null. 44 | ``` 45 | 46 | 47 | ``` 48 | 49 | 同理我们编写decodeResource的重载函数 50 | ``` 51 | public static Bitmap getFitSampleBitmap(Resources resources, int resId, int width, int height) { 52 | BitmapFactory.Options options = new BitmapFactory.Options(); 53 | options.inJustDecodeBounds = true; 54 | BitmapFactory.decodeResource(resources, resId, options); 55 | options.inSampleSize = getFitInSampleSize(width, height, options); 56 | options.inJustDecodeBounds = false; 57 | return BitmapFactory.decodeResource(resources, resId, options); 58 | } 59 | ``` 60 | 61 | 62 |        对于decodeStream重载，和从file中加载和从resource中加载稍有不同，因对stream是一种有顺序的字符流，对其decode一次后，其顺序就会发生变化，再次进行第二次decode的时候就不能解码成功了，这也是为什么当我们对inputStream decode两次的时候会得到一个null值的bitmap的原因。 63 | 64 |        所以我们对stream类型的源需要进行转换，转换有两种思路: 65 | 1. 将inputStream的字节流读取后放到一个byte[]数组里，然后使用BitmapFactory.decodeByteArray两次decode进行压缩——但是发现这种方法其实治标不治本，不建议使用。具体原因接下来会介绍。 66 | 2. 将inputStream的字节流读取到一个文件里，然后通过处理file的方式来进行处理即可——推荐，好处多，后面介绍。 67 | 68 | 1.通过decodeByteArray的形式： 69 | ``` 70 | public static Bitmap getFitSampleBitmap(InputStream inputStream, int width, int height) throws Exception { 71 | BitmapFactory.Options options = new BitmapFactory.Options(); 72 | options.inJustDecodeBounds = true; 73 | byte[] bytes = readStream(inputStream); 74 | //BitmapFactory.decodeStream(inputStream, null, options); 75 | BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options); 76 | options.inSampleSize = getFitInSampleSize(width, height, options); 77 | options.inJustDecodeBounds = false; 78 | // return BitmapFactory.decodeStream(inputStream, null, options); 79 | return BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options); 80 | } 81 | 82 | /* 83 | * 从inputStream中获取字节流 数组大小 84 | * */ 85 | public static byte[] readStream(InputStream inStream) throws Exception { 86 | ByteArrayOutputStream outStream = new ByteArrayOutputStream(); 87 | byte[] buffer = new byte[1024]; 88 | int len = 0; 89 | while ((len = inStream.read(buffer)) != -1) { 90 | outStream.write(buffer, 0, len); 91 | } 92 | outStream.close(); 93 | inStream.close(); 94 | return outStream.toByteArray(); 95 | } 96 | ``` 97 |        我们发现这里的处理方式大致一看还可以，然后我们会发现在readStream函数中会返回一个byte[]数组，在这个数组的大小即为原始图像的大小，因此并没有起到节省内存的效果。 98 | 99 | 因此推荐使用第二中方式通过保存本地文件后再解码 100 | 101 | ``` 102 | public static Bitmap getFitSampleBitmap(InputStream inputStream, String catchFilePath,int width, int height) throws Exception { 103 | return getFitSampleBitmap(catchStreamToFile(catchFilePath, inputStream), width, height); 104 | } 105 | /* 106 | * 将inputStream中字节流保存至文件 107 | * */ 108 | public static String catchStreamToFile(String catchFile,InputStream inStream) throws Exception { 109 | 110 | File tempFile=new File(catchFile); 111 | try { 112 | if (tempFile.exists()) { 113 | tempFile.delete(); 114 | } 115 | tempFile.createNewFile(); 116 | } catch (IOException e) { 117 | e.printStackTrace(); 118 | } 119 | FileOutputStream fileOutputStream=new FileOutputStream(tempFile); 120 | byte[] buffer = new byte[1024]; 121 | int len = 0; 122 | while ((len = inStream.read(buffer)) != -1) { 123 | fileOutputStream.write(buffer, 0, len); 124 | } 125 | inStream.close(); 126 | fileOutputStream.close(); 127 | return catchFile; 128 | } 129 | ``` 130 |        这里我们可以看到，我们通过调用catchStreamToFile先将文件保存到指定文件名里，然后再利用两次decodeFile的形式来处理stream流的。 131 | 这样做的好处是什么呢： 132 | 1.避免了超大的中间内存变量的生成，所以自然就避免了oom现象。 133 | 2.对于从file和resource中加载图片其本质都是从文件中加载图片的。 134 | 3.一般inputStream都是应用于网络中获取图片的方式，我们采用了用文件进行缓存的方式进行图片加载还有效的避免了来回切换activity页面时多次从网络中下载同一种图片，从而造成的卡顿现象，使用这种方法，我们加载一次后，再进行第二次加载时，我们可以判断下是否是和第一次加载时的url是一致的，如果是那么直接从使用getFitSampleBitmap file的重载从第一次缓存的catchfile中加载即可，这样大大提高了加载速度(在主程序里我们可以用一个map变量保存下url和catchFileName的对应关系)。 135 | **内存对比** 136 |        这样我们加载相关代码就完成了，最后我们通过一个demo来对比下正确加载图像和不处理的加载图像时的内存消耗吧，这里我们就写一个手机拍摄头像的程序吧。 137 | 138 | 还是一样一边看代码一边讲解吧: 139 | 140 | ``` 141 | 142 | 150 | 156 | 157 | 164 |