如何使用java方法？

Question

我想编写一个简单的java代理,它可以打印由java程序调用的方法的名称.

例如,我想要的java程序是:

public class TestInstr {

public static void sayHello() {
    System.out.println("Hello !");
}

public static void main(String args[]) {
    sayHello();
    sayHello();
    sayHello();
 }

}

我想展示这样的东西:

method sayHello has been called
Hello !
method sayHello has been called
Hello !
method sayHello has been called
Hello !

谢谢你的帮助!

Answer 1

您可以使用Javassist等检测库来执行此操作.

让我举一个单个方法的示例,您可以使用Javassist或反射将其扩展到所有方法:

ClassPool pool = ClassPool.getDefault();
CtClass cc = pool.get("TestInstr");
CtMethod m = cc.getDeclaredMethod("sayHello");
m.insertBefore("{ System.out.println(\"method sayHello has been called\"); }");
cc.writeFile();

有关详细信息,请查看此链接:http://www.csg.ci.iu-tokyo.ac.jp/~chiba/javassist/tutorial/tutorial2.html#intro