Small Example of JDK dynamic proxy

1. File List:

Business interface: userservice

Business implementation: userserviceimpl

Proxy class call handler implementation: proxyhandler

2. Do not talk nonsense. paste the Code:

package com.niewj.service;import com.niewj.model.User;public interface UserService {void add(User user);void delete(User user);}

package com.niewj.service;import com.niewj.model.User;public class UserServiceImpl implements UserService {@Overridepublic void add(User user) {System.out.println("User Saved. & ");}@Overridepublic void delete(User user) {System.out.println("User Deleted. &");}}

Package COM. niewj. service; import Java. lang. reflect. invocationhandler; import Java. lang. reflect. method;/*** JDK dynamic proxy simulation ** 1. first, identify what is the target object and what is the proxy object proxy !! ** 2. Each proxy object has a related invocationhandler object. * When a contemporary rational object is generated, it is the created proxy object. * The invocationhandler object is used to automatically call the invoke method implemented in the handler class. * The following passage comes from @ javadoc @ * <p> Each proxy instance has an associated invocation handler. * When a method is invoked on a proxy instance, the method * invocation is encoded and dispatched to the <code> invoke </code> * method of its invocation handler. ** 3. another reason is that I found that the TMD output sequence in my eclipse console is incorrect. I often thought that something went wrong with my character. * I don't know if the console information is not stack-based output. (Good detour) **/public class proxyhandler implements invocationhandler {// create a proxy object for this target class. Private object target; // The instance that transmits the proxy target because the proxy processor needs it. You can also use the set method. Public proxyhandler (object target) implements this.tar get = target;}/** this method is called for the proxy object. * Note that the object called by the internal method is the target object. Do not write an error. * // @ Overridepublic object invoke (Object proxy, method, object [] ARGs) throws throwable {object ret = NULL; // 1. cutdomainbefore (method. getname (); ret = method. invoke (target, argS); // 2. cutaskafter (method. getname (); return ret;} public void cutaskbefore (string mname) {system. err. println ("calling ____" + mname + "() ____ method");} public void cutpattern after (string mname) {system. err. println ("calling ____" + mname + "() ____ method ");}}

Testing Area:

Package COM. niewj; import Java. lang. reflect. proxy; import Org. JUnit. test; import COM. niewj. model. user; import COM. niewj. service. proxyhandler; import COM. niewj. service. userservice; import COM. niewj. service. userserviceimpl; public class springproxytest {@ test @ suppresswarnings ("rawtypes") Public void testjdkdynamicproxy () {/* 1. obtain the userserviceimpl object -- the target object -- that is, the object to be proxy. */Userservice = new userserviceimpl (); // obtain the current class name class clazz = userservice. getclass ();/** 2. Obtain the proxy object. * Each proxy object has a related invocationhandler object. The invoke of this handler object is used to implement the custom tricky behavior to be completed in the call *. You can use the proxy class and custom call processing logic to generate a proxy object. */Userservice userserviceproxy = (userservice) proxy. newproxyinstance (clazz. getclassloader (), clazz. getinterfaces (), new proxyhandler (userservice); userserviceproxy. add (new user ("dotjar"); userserviceproxy. delete (new user ("DDD "));}}

3. Conclusion: in the code, look up