Java動態代理三——模擬AOP實現

以下案例模擬AOP實現

目錄結構

接口PersonService

package com.ljq.service;

public interface PersonService {
    public void save(String name);
    public void update(String name, Integer personId);
    public String getPersonName(Integer personId);
}

實現類PersonServiceBean

package com.ljq.service.impl;

import com.ljq.service.PersonService;

public class PersonServiceBean implements PersonService {
    private String user = null;

    public PersonServiceBean() {
        super();
    }

    public PersonServiceBean(String user) { 
        super();
        this.user = user;
    }

    public String getPersonName(Integer personId) {
        System.out.println("我是getPersonName()方法");
        return "get";
    }

    public void save(String name) {
        System.out.println("我是save()方法");
    }

    public void update(String name, Integer personId) {
        System.out.println("我是update()方法");
    }

    public String getUser() {
        return user;
    }

    public void setUser(String user) {
        this.user = user;
    }
}

動態代理類JDKProxyFactory

package com.ljq.aop;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

import com.ljq.service.impl.PersonServiceBean;

public class JDKProxyFactory implements InvocationHandler {
    //要代理的原始對象
    private Object targer;
    
    /**
     * 創建動態代理
     * 
     * @param targer 要代理的原始對象
     * @return
     */
    public Object createProxyInstance(Object targer){
        this.targer=targer;
        return Proxy.newProxyInstance(
                this.targer.getClass().getClassLoader(), 
                this.targer.getClass().getInterfaces(),
                this);
    }

    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        Object result = null;
        PersonServiceBean bean = (PersonServiceBean) this.targer;
        if (bean.getUser() != null) {
            // 前置通知
            doBefore();
            try {
                result = method.invoke(targer, args);
                // 後置通知
                doAfter();
            } catch (Exception e) {
                // 例外通知
                doException();
            } finally {
                // 最終通知
                doFinally();
            }
        }
        return result;
    }

    private void doBefore() {
        System.out.println("我是前置通知");
    }

    private void doAfter() {
        System.out.println("我是後置通知");
    }

    private void doException() {
        System.out.println("我是例外通知");
    }

    private void doFinally() {
        System.out.println("我是最終通知");
    }

}

動態代理類CGlibProxyFactory：使用CGLIB技術

package com.ljq.aop;

import java.lang.reflect.Method;

import com.ljq.service.impl.PersonServiceBean;

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

public class CGlibProxyFactory implements MethodInterceptor{
    private Object target;

    public Object createProxyInstance(Object target){
        this.target=target;
        Enhancer enhancer=new Enhancer();
        enhancer.setSuperclass(this.target.getClass());//非final
        enhancer.setCallback(this);
        return enhancer.create();
    }
    
    public Object intercept(Object proxy, Method method, Object[] args,
            MethodProxy methodProxy) throws Throwable {
        Object result=null;
        PersonServiceBean bean=(PersonServiceBean)this.target;
        if(bean.getUser()!=null){
            // 前置通知
            doBefore();
            try {
                result = methodProxy.invoke(target, args);
                // 後置通知
                doAfter();
            } catch (Exception e) {
                // 例外通知
                doException();
            } finally {
                // 最終通知
                doFinally();
            }
        }
        return result;
    }

    private void doBefore() {
        System.out.println("我是前置通知");
    }

    private void doAfter() {
        System.out.println("我是後置通知");
    }

    private void doException() {
        System.out.println("我是例外通知");
    }

    private void doFinally() {
        System.out.println("我是最終通知");
    }

}

測試類AopTest

package com.ljq.test;

import com.ljq.aop.CGlibProxyFactory;
import com.ljq.aop.JDKProxyFactory;
import com.ljq.service.PersonService;
import com.ljq.service.impl.PersonServiceBean;

public class AopTest {

    public static void main(String[] args) {
        proxyTest();
        proxyTest2();
    }
    
    private static void proxyTest() {
        JDKProxyFactory jdkProxyFactory=new JDKProxyFactory();
        PersonService personService=(PersonService)jdkProxyFactory.
             createProxyInstance(new PersonServiceBean("zhangsan"));
        personService.getPersonName(1);
    }
    
    private static void proxyTest2() {
        CGlibProxyFactory cglibProxyFactory=new CGlibProxyFactory();
        PersonServiceBean bean=(PersonServiceBean)cglibProxyFactory.
             createProxyInstance(new PersonServiceBean("lisi"));
        bean.save("a");
        
    }
}

運行結果