簡介¶

1. mian方法之前，執行
2. Java Agent 則是一個可以讓你在 Java runtime 即時改 bytecode 的技術。

內容¶

• 需要打包成jar
• META-INF/MANIFEST.MF
• java -javaagent:myagent.jar=thisIsAgentArgs -jar thisIsMain.jar

// MANIFEST.MF
Manifest-Version: 1.0
Premain-Class: tk.tommy.MyAgent
Can-Redefine-Classes: true


package tk.tommy;
public class MyAgent {
    public static void premain(String agentArgs, Instrumentation instrumentation) {
        System.out.println("=========premain方法执行========");
        System.out.println(agentArgs);
        System.out.println(instrumentation);
    }
}

用 Java Agent 實作 AOP Spring Loaded is a JVM agent for reloading class file changes whilst a JVM is running

參考資料¶