├── app
    ├── pom.xml
    └── src
    │   └── main
    │       └── java
    │           └── com
    │               └── git
    │                   └── hui
    │                       └── java
    │                           ├── AttachMain.java
    │                           ├── BaseMain.java
    │                           └── DemoClz.java
├── cost-agent
    ├── build.sh
    ├── pom.xml
    └── src
    │   └── main
    │       └── java
    │           └── com
    │               └── git
    │                   └── hui
    │                       └── agent
    │                           ├── CostAgent.java
    │                           └── CostTransformer.java
├── pom.xml
├── readme.md
└── simple-agent
    ├── build.sh
    ├── pom.xml
    └── src
        └── main
            ├── java
                └── com
                │   └── git
                │       └── hui
                │           └── agent
                │               └── SimpleAgent.java
            └── resources
                └── META-INF
                    └── MANIFEST.MF


/app/pom.xml:
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 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <project xmlns="http://maven.apache.org/POM/4.0.0"
 3 |          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4 |          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5 |     <parent>
 6 |         <artifactId>java-agent</artifactId>
 7 |         <groupId>com.git.hui.demo</groupId>
 8 |         <version>1.0-SNAPSHOT</version>
 9 |     </parent>
10 |     <modelVersion>4.0.0</modelVersion>
11 | 
12 |     <artifactId>app</artifactId>
13 | 
14 | 
15 | </project>


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/app/src/main/java/com/git/hui/java/AttachMain.java:
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 1 | package com.git.hui.java;
 2 | 
 3 | import com.sun.tools.attach.AgentInitializationException;
 4 | import com.sun.tools.attach.AgentLoadException;
 5 | import com.sun.tools.attach.AttachNotSupportedException;
 6 | import com.sun.tools.attach.VirtualMachine;
 7 | 
 8 | import java.io.IOException;
 9 | 
10 | /**
11 |  * Created by @author yihui in 19:48 20/3/15.
12 |  */
13 | public class AttachMain {
14 | 
15 | 
16 |     public static void main(String[] args)
17 |             throws IOException, AgentLoadException, AgentInitializationException, AttachNotSupportedException {
18 |         // 用jps -l 查出目标应用的进程号，替换下面的参数
19 |         VirtualMachine vm = VirtualMachine.attach("36633");
20 |         // 用你自己的agent绝对地址替换
21 |         vm.loadAgent(
22 |                 "/Users/user/Project/GitHub/study-demo/java-agent/target/java-agent-1.0-SNAPSHOT-jar-with-dependencies.jar");
23 |     }
24 | 
25 | }
26 | 


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/app/src/main/java/com/git/hui/java/BaseMain.java:
--------------------------------------------------------------------------------
 1 | package com.git.hui.java;
 2 | 
 3 | /**
 4 |  * Created by @author yihui in 19:41 20/3/15.
 5 |  */
 6 | public class BaseMain {
 7 | 
 8 |     public int print(int i) {
 9 |         System.out.println("i: " + i);
10 |         try {
11 |             Thread.sleep(1000);
12 |         } catch (InterruptedException e) {
13 |             e.printStackTrace();
14 |         }
15 | 
16 |         if (i > 5) {
17 |             // 主要是为了演示抛异常，也会执行方法耗时统计的case
18 |             throw new RuntimeException();
19 |         }
20 | 
21 |         return i + 2;
22 |     }
23 | 
24 |     public void run() {
25 |         int i = 1;
26 |         while (true) {
27 |             try {
28 |                 i = print(i);
29 |             } catch (Exception e) {
30 |                 e.printStackTrace();
31 |             }
32 |         }
33 |     }
34 | 
35 |     public static void main(String[] args) {
36 |         BaseMain main = new BaseMain();
37 |         main.run();
38 | //
39 | //        DemoClz demoClz = new DemoClz();
40 | //        int cnt = 0;
41 | //        for (int i = 0; i < 20; i++) {
42 | //            if (++cnt % 2 == 0) {
43 | //                i = demoClz.print(i);
44 | //            } else {
45 | //                i = demoClz.count(i);
46 | //            }
47 | //        }
48 |     }
49 | }
50 | 


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/app/src/main/java/com/git/hui/java/DemoClz.java:
--------------------------------------------------------------------------------
 1 | package com.git.hui.java;
 2 | 
 3 | /**
 4 |  * Created by @author yihui in 22:07 20/3/15.
 5 |  */
 6 | public class DemoClz {
 7 | 
 8 |     public int print(int i) {
 9 |         System.out.println("print: " + i);
10 |         try {
11 |             Thread.sleep(1000);
12 |         } catch (InterruptedException e) {
13 |             e.printStackTrace();
14 |         }
15 |         return i + 2;
16 |     }
17 | 
18 |     public int count(int i) {
19 |         System.out.println("count: " + i);
20 |         try {
21 |             Thread.sleep(50);
22 |         } catch (InterruptedException e) {
23 |             e.printStackTrace();
24 |         }
25 |         return i + 1;
26 |     }
27 | }
28 | 


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/cost-agent/build.sh:
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1 | mvn assembly:assembly
2 | 


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/cost-agent/pom.xml:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <project xmlns="http://maven.apache.org/POM/4.0.0"
 3 |          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4 |          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5 |     <parent>
 6 |         <artifactId>java-agent</artifactId>
 7 |         <groupId>com.git.hui.demo</groupId>
 8 |         <version>1.0-SNAPSHOT</version>
 9 |     </parent>
10 |     <modelVersion>4.0.0</modelVersion>
11 | 
12 |     <artifactId>cost-agent</artifactId>
13 | 
14 |     <dependencies>
15 |         <dependency>
16 |             <groupId>javassist</groupId>
17 |             <artifactId>javassist</artifactId>
18 |             <version>3.12.1.GA</version>
19 |         </dependency>
20 |     </dependencies>
21 | 
22 |     <build>
23 |         <plugins>
24 |             <plugin>
25 |                 <groupId>org.apache.maven.plugins</groupId>
26 |                 <artifactId>maven-assembly-plugin</artifactId>
27 |                 <configuration>
28 |                     <descriptorRefs>
29 |                         <descriptorRef>jar-with-dependencies</descriptorRef>
30 |                     </descriptorRefs>
31 |                     <archive>
32 |                         <manifestEntries>
33 |                             <Premain-Class>com.git.hui.agent.CostAgent</Premain-Class>
34 |                             <Agent-Class>com.git.hui.agent.CostAgent</Agent-Class>
35 |                             <Can-Redefine-Classes>true</Can-Redefine-Classes>
36 |                             <Can-Retransform-Classes>true</Can-Retransform-Classes>
37 |                         </manifestEntries>
38 |                     </archive>
39 |                 </configuration>
40 | 
41 |                 <executions>
42 |                     <execution>
43 |                         <goals>
44 |                             <goal>attached</goal>
45 |                         </goals>
46 |                         <phase>package</phase>
47 |                     </execution>
48 |                 </executions>
49 |             </plugin>
50 |         </plugins>
51 |     </build>
52 | 
53 | 
54 | </project>


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/cost-agent/src/main/java/com/git/hui/agent/CostAgent.java:
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 1 | package com.git.hui.agent;
 2 | 
 3 | import java.lang.instrument.Instrumentation;
 4 | 
 5 | /**
 6 |  * Created by @author yihui in 10:46 20/3/16.
 7 |  */
 8 | public class CostAgent {
 9 | 
10 |     /**
11 |      * jvm 参数形式启动，运行此方法
12 |      *
13 |      * manifest需要配置属性Premain-Class
14 |      *
15 |      * @param agentArgs
16 |      * @param inst
17 |      */
18 |     public static void premain(String agentArgs, Instrumentation inst) {
19 |         System.out.println("premain");
20 |         customLogic(inst);
21 |     }
22 | 
23 |     /**
24 |      * 动态 attach 方式启动，运行此方法
25 |      *
26 |      * manifest需要配置属性Agent-Class
27 |      *
28 |      * @param agentArgs
29 |      * @param inst
30 |      */
31 |     public static void agentmain(String agentArgs, Instrumentation inst) {
32 |         System.out.println("agentmain");
33 |         customLogic(inst);
34 |     }
35 | 
36 |     /**
37 |      * 统计方法耗时
38 |      *
39 |      * @param inst
40 |      */
41 |     private static void customLogic(Instrumentation inst) {
42 |         inst.addTransformer(new CostTransformer(), true);
43 |     }
44 | }
45 | 


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/cost-agent/src/main/java/com/git/hui/agent/CostTransformer.java:
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 1 | package com.git.hui.agent;
 2 | 
 3 | import javassist.ClassPool;
 4 | import javassist.CtClass;
 5 | import javassist.CtMethod;
 6 | 
 7 | import java.io.ByteArrayInputStream;
 8 | import java.lang.instrument.ClassFileTransformer;
 9 | import java.security.ProtectionDomain;
10 | 
11 | /**
12 |  * Created by @author yihui in 19:58 20/3/15.
13 |  */
14 | public class CostTransformer implements ClassFileTransformer {
15 |     @Override
16 |     public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
17 |             ProtectionDomain protectionDomain, byte[] classfileBuffer) {
18 |         if (!className.startsWith("com/git/hui/java/")) {
19 |             return classfileBuffer;
20 |         }
21 | 
22 |         CtClass cl = null;
23 |         try {
24 |             ClassPool classPool = ClassPool.getDefault();
25 |             cl = classPool.makeClass(new ByteArrayInputStream(classfileBuffer));
26 | 
27 |             for (CtMethod method : cl.getDeclaredMethods()) {
28 |                 // 我们统计一下所有的方法调用耗时
29 |                 method.addLocalVariable("start", CtClass.longType);
30 |                 method.insertBefore("start = System.currentTimeMillis();");
31 |                 String methodName = method.getLongName();
32 |                 // 请注意第二个参数，设置为true，则表示即便抛出异常了，下面的代码也会执行；相当于将它封装在finally里面了
33 |                 method.insertAfter("System.out.println(\"" + methodName + " cost: \" + (System" +
34 |                         ".currentTimeMillis() - start));", true);
35 |             }
36 | 
37 |             byte[] transformed = cl.toBytecode();
38 |             return transformed;
39 |         } catch (Exception e) {
40 |             e.printStackTrace();
41 |         }
42 |         return classfileBuffer;
43 |     }
44 | }
45 | 


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/pom.xml:
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 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <project xmlns="http://maven.apache.org/POM/4.0.0"
 3 |          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4 |          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5 |     <modelVersion>4.0.0</modelVersion>
 6 | 
 7 |     <groupId>com.git.hui.demo</groupId>
 8 |     <artifactId>java-agent</artifactId>
 9 |     <packaging>pom</packaging>
10 |     <version>1.0-SNAPSHOT</version>
11 |     <modules>
12 |         <module>simple-agent</module>
13 |         <module>app</module>
14 |         <module>cost-agent</module>
15 |     </modules>
16 | 
17 | 
18 | </project>


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/readme.md:
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 1 | ## java-agent
 2 | 
 3 | 提供了一个基于idea + maven构建java agent开发测试环境的项目，其中simple-agent子工程演示了一个hello world版本的java agent项目，并提供了两种打包方式，直接执行`build.sh`即可在target下获取到可用的agent包
 4 | 
 5 | app项目作为测试目标程序，同样提供了两种使用姿势，通过-jvm参数指定agent，以及通过attach方式挂载目标进程
 6 | 
 7 | 更多详细内容，请参考博文:
 8 | 
 9 | - [200303-如何优雅的在java中统计代码块耗时](https://mp.weixin.qq.com/s/3cw3WsTUG94-C9894EBXUQ)
10 | - [200316-IDEA + maven零基础构建java agent项目](https://blog.hhui.top/hexblog/2020/03/16/200316-IDEA-maven%E9%9B%B6%E5%9F%BA%E7%A1%80%E6%9E%84%E5%BB%BAjava-agent%E9%A1%B9%E7%9B%AE/)
11 | - [200316-手把手教你实现一个方法耗时统计的java agent](https://blog.hhui.top/hexblog/2020/03/16/200316-%E6%89%8B%E6%8A%8A%E6%89%8B%E6%95%99%E4%BD%A0%E5%AE%9E%E7%8E%B0%E4%B8%80%E4%B9%AA%E6%96%B9%E6%B3%95%E8%80%97%E6%97%B6%E7%BB%9F%E8%AE%A1%E7%9A%84java-agent/)
12 | 
13 | 
14 | 


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/simple-agent/build.sh:
--------------------------------------------------------------------------------
1 | mvn assembly:assembly
2 | 


--------------------------------------------------------------------------------
/simple-agent/pom.xml:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <project xmlns="http://maven.apache.org/POM/4.0.0"
 3 |          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4 |          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5 |     <parent>
 6 |         <artifactId>java-agent</artifactId>
 7 |         <groupId>com.git.hui.demo</groupId>
 8 |         <version>1.0-SNAPSHOT</version>
 9 |     </parent>
10 |     <modelVersion>4.0.0</modelVersion>
11 | 
12 |     <artifactId>simple-agent</artifactId>
13 | 
14 |     <build>
15 |         <plugins>
16 |             <plugin>
17 |                 <groupId>org.apache.maven.plugins</groupId>
18 |                 <artifactId>maven-assembly-plugin</artifactId>
19 |                 <configuration>
20 |                     <descriptorRefs>
21 |                         <descriptorRef>jar-with-dependencies</descriptorRef>
22 |                     </descriptorRefs>
23 |                     <archive>
24 |                         <manifestFile>
25 |                             src/main/resources/META-INF/MANIFEST.MF
26 |                         </manifestFile>
27 |                         <!--<manifestEntries>-->
28 |                         <!--<Premain-Class>com.git.hui.agent.SimpleAgent</Premain-Class>-->
29 |                         <!--<Agent-Class>com.git.hui.agent.SimpleAgent</Agent-Class>-->
30 |                         <!--<Can-Redefine-Classes>true</Can-Redefine-Classes>-->
31 |                         <!--<Can-Retransform-Classes>true</Can-Retransform-Classes>-->
32 |                         <!--</manifestEntries>-->
33 |                     </archive>
34 |                 </configuration>
35 | 
36 |                 <executions>
37 |                     <execution>
38 |                         <goals>
39 |                             <goal>attached</goal>
40 |                         </goals>
41 |                         <phase>package</phase>
42 |                     </execution>
43 |                 </executions>
44 |             </plugin>
45 |         </plugins>
46 |     </build>
47 | 
48 | </project>


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/simple-agent/src/main/java/com/git/hui/agent/SimpleAgent.java:
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 1 | package com.git.hui.agent;
 2 | 
 3 | import java.lang.instrument.Instrumentation;
 4 | 
 5 | /**
 6 |  * Created by @author yihui in 16:39 20/3/15.
 7 |  */
 8 | public class SimpleAgent {
 9 | 
10 |     /**
11 |      * jvm 参数形式启动，运行此方法
12 |      *
13 |      * manifest需要配置属性Premain-Class
14 |      *
15 |      * @param agentArgs
16 |      * @param inst
17 |      */
18 |     public static void premain(String agentArgs, Instrumentation inst) {
19 |         System.out.println("premain");
20 |     }
21 | 
22 |     /**
23 |      * 动态 attach 方式启动，运行此方法
24 |      *
25 |      * manifest需要配置属性Agent-Class
26 |      *
27 |      * @param agentArgs
28 |      * @param inst
29 |      */
30 |     public static void agentmain(String agentArgs, Instrumentation inst) {
31 |         System.out.println("agentmain");
32 |     }
33 | }
34 | 


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/simple-agent/src/main/resources/META-INF/MANIFEST.MF:
--------------------------------------------------------------------------------
1 | Manifest-Version: 1.0
2 | Premain-Class: com.git.hui.agent.SimpleAgent
3 | Agent-Class: com.git.hui.agent.SimpleAgent
4 | Can-Redefine-Classes: true
5 | Can-Retransform-Classes: true
6 | 


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