利用instrumentation打印运行过程中实际使用到的java类

MANIFEST.MF

Manifest-Version: 1.0
Premain-Class: test.PrintClsAgent

PrintClsAgent.java

public class PrintClsAgent {

    public static void premain(String args, Instrumentation inst) {
        File f = new File(args);
        try {
            final FileWriter fw = new FileWriter(f);
            inst.addTransformer(new ClassFileTransformer() {

                public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
                                        ProtectionDomain protectionDomain, byte[] classfileBuffer)
                                                                                                  throws IllegalClassFormatException {
                    try {
                        fw.write(className + "\n");
                        fw.flush();
                    } catch (IOException e) {
                        throw new RuntimeException(e);
                    }
                    return classfileBuffer;
                }
            });
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static void agentmain(String args, Instrumentation inst) {
        premain(args, inst);
    }
}

运行时传给vm参数：-javaagent:/tmp/prtCls.jar=/tmp/class.txt