动态代理

一、使用CGLIB

1、pom.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>CommonMavenProject</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib</artifactId>
            <version>3.3.0</version>
        </dependency>
    </dependencies>

</project>

2、被代理类

package cglib;

public class TargetClass
{
    public void doIt()
    {
        System.out.println("targetclass的do方法被调用");
    }
}

3、代理

package cglib;

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

import java.lang.reflect.Method;

public class CglibProxyInterceptor implements MethodInterceptor
{

    @Override
    public Object intercept(Object object, Method method, Object[] args
            , MethodProxy methodProxy) throws Throwable
    {
        System.out.println("cgLibProxyInterceptor开始执行");
        Object obj = methodProxy.invokeSuper(object,args);
        System.out.println("cgLibProxyInterceptor执行完毕");
        return obj;
    }
}

4、测试

package cglib;

import net.sf.cglib.proxy.Enhancer;

public class CglibDynamicProxyExample
{
    public static void main(String[] args)
    {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(TargetClass.class);
        enhancer.setCallback(new CglibProxyInterceptor());
        TargetClass proxy = (TargetClass) enhancer.create();
        proxy.doIt();
    }
}

二、使用JDK自带的InvocationHandler

1、接口

package invocationHandler;

public interface Subject
{
    void doIt();
}

2、被代理类

package invocationHandler;



public class RealObject implements Subject
{
    @Override
    public void doIt()
    {
        System.out.println("RealObject doIt在执行");
    }
}

3、代理类

package invocationHandler;

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

public class DynamicProxyInvocationHandler implements InvocationHandler
{
    private Object target;

    public DynamicProxyInvocationHandler(Object target)
    {
        this.target = target;
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
    {
        System.out.println("DynamicProxyInvocationHandler在执行 ");
        Object obj = method.invoke(target, args);
        System.out.println("DynamicProxyInvocationHandler执行完毕");
        return obj;
    }
}

4、测试

package invocationHandler;

import java.lang.reflect.Proxy;

public class Tester
{
    public static void main(String[] args)
    {
        Subject subject = new RealObject();
        Subject proxySubject = (Subject)Proxy.newProxyInstance(Subject.class.getClassLoader(), new Class[]{Subject.class},
                new DynamicProxyInvocationHandler(subject));
        proxySubject.doIt();
    }
}