How to modify code dynamically at run time in javassist

Javassist how to dynamically modify code at runtime, I believe many inexperienced people are helpless about this, this article summarizes the causes of the problem and solutions, through this article I hope you can solve this problem.

Javassist is a Java class handler commonly used to implement dynamic proxies. Used to implement proxy functionality in various frameworks.

Pros:

0 Ability to operate class

1 can modify class files at runtime

2 widely dependent (hibernate,mybatis will apply its jar package, no need to refer again)

Related code://Listen to port 8000, set//java -agentlib in startup parameters:jdwp=transport=dt_socket,server=y,suspend=n,address=8000HotSwapper hs = new HotSwapper(8000);// ClassPool cp = ClassPool.getDefault();//Get class String clsName = C2.C8.class.getName();CtClass cc = cp.get(clsName);//Get method CtMethod m = cc.getDeclaredMethod ("getSerial");//Rewrite method m.setBody("{ return getM(); }");//Call System.out.println(C2.C8.getM()) once;hs.reload(clsName, cc.toBytecode());//Call System.out.println(C2.C8.getM()) once more; Note:

0 JVM does not allow multiple versions of a class. Changing class requires attention.

1 Need to enable JPDA support Load class java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000

2 Open JPDA will affect debug

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