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This article is about how to use jdk dynamic agent and Cglib dynamic agent in java. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

JDK dynamic agent

Jdk dynamic proxy can only proxy interface, because java's single inheritance dynamic proxy class inherits Proxy class, so it can not inherit other classes, so it can only rely on interface to implement the interface of the proxied class.

Case study

Public interface UserManager {

Void addUser (Integer id,String userName)

Void delUser (Integer id)

Void findUser (Integer id)

Void modifyUser (Integer id,String userName)

}

Public class UserManagerImpl implements UserManager {

@ Override

Public void addUser (Integer id,String userName) {

System.out.println ("userManager.addUser ()")

}

@ Override

Public void delUser (Integer id) {

System.out.println ("userManager.delUser ()")

}

@ Override

Public void findUser (Integer id) {

System.out.println ("userManager.findUser ()")

}

@ Override

Public void modifyUser (Integer id,String userName) {

System.out.println ("userManager.modifyUser ()")

}

}

Public class LogHandler implements InvocationHandler {

/ / Target object

Private Object targetObject

Public Object newProxyInstance (Object targetObject) {

This.targetObject=targetObject

/ *

* param1 the classloader to load the proxy object

* APIs that need to be implemented by param2

* when the param3 dynamic proxy method is executed, the invoke method is called to execute

* /

Return Proxy.newProxyInstance (targetObject.getClass (). GetClassLoader (), targetObject.getClass (). GetInterfaces (), this)

}

@ Override

Public Object invoke (Object proxy, Method method, Object [] args) throws Throwable {

/ / print target method parameters

For (int I = 0; I < args.length; iTunes +) {

System.out.println (args [I])

}

Object ret=null

Try {

System.out.println ("start"); / / before executing the target method

Ret=method.invoke (targetObject, args)

System.out.println ("success"); / / after executing the target method

} catch (Exception e) {

E.printStackTrace ()

System.out.println ("error")

Throw e

}

Return ret

}

}

Cglib dynamic agent

Cglib means that a subclass inherits the specified class and overrides the class method, so it is best not to add a final modifier to the specified class

Case study

Cglib needs to rely on packages

Cglib

Cglib

2.2.2

/ / Cglib dynamic proxy implements MethodInterceptor interface

Public class CglibProxy implements MethodInterceptor {

Private Object target

@ Override Zhengzhou abortion specialist Hospital http://www.03912316666.com/

Public Object intercept (Object obj, Method method, Object [] args, MethodProxy proxy) throws Throwable {

System.out.println ("start")

/ / output target method parameters

For (int I = 0; I < args.length; iTunes +) {

System.out.println (args [I])

}

Object invoke=method.invoke (target, args)

System.out.println ("end")

Return invoke

}

Public Object getCglibProxy (Object targetObject) {

This.target=targetObject

Enhancer enhancer=new Enhancer ()

/ / because Cglig needs to generate a subclass, you need to specify a parent class

Enhancer.setSuperclass (targetObject.getClass ())

Enhancer.setCallback (this)

Object result=enhancer.create (); / / create and return a proxy object

Return result

}

Public static void main (String [] args) {

CglibProxy cglibProxy=new CglibProxy ()

UserManagerImpl userManager= (UserManagerImpl) cglibProxy.getCglibProxy (new UserManagerImpl ())

UserManager.addUser (66 "6666")

}

}

/ / the parent interface is not implemented

Public class UserManagerImpl {

Public void addUser (Integer id,String userName) {

System.out.println ("userManager.addUser ()")

}

Public void delUser (Integer id) {

System.out.println ("userManager.delUser ()")

}

Public void findUser (Integer id) {

System.out.println ("userManager.findUser ()")

}

Public void modifyUser (Integer id,String userName) {

System.out.println ("userManager.modifyUser ()")

}

}

Thank you for reading! This is the end of this article on "how to use jdk dynamic Agent and Cglib dynamic Agent in java". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it out for more people to see!

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