Java静态代理和动态代理总结

静态代理

第一种实现(基于接口)：

1》接口

public interface Hello {

    void say(String msg);}

2》目标类，至少实现一个接口

public class HelloImpl implements Hello {    public void say(String msg) {        System.out.println("Hi,"+msg);    }}

3》代理类(与目标类实现相同接口，从而保证功能一致)

public class HelloProxy implements Hello{

private Hello hello;

public HelloProxy(Hello hello){        this.hello = hello;    }

public void say(String msg){        before();        hello.say(msg);        after();    }    private void before(){        System.out.println("Before");    }    private void after(){        System.out.println("After");    }}

3》测试

/** * @Author LZHL * @Create 2017-02-19 10:26 * @Description */public class Main {    public static void main(String[] args) throws Exception {        HelloImpl target = new HelloImpl();        HelloProxy proxy = new HelloProxy(target);        proxy.say("LZHL");    }}

第二种实现(基于目标类)：

1>目标类

public class HelloTarget {    public void sayHello(String name){        System.out.println("Hi,"+name);    }}

2>代理类(通过继承目标类，保证功能一致)

public class HelloProxy extends HelloTarget{　　private HelloTarget target;　　public HelloProxy(HelloTarget target){　　　　this.target = target;　　} 　　@Override    public void sayHello(String name) {        this.before();        target.sayHello(name);        this.after();    }    private void before(){        System.out.println("Before");    }    private void after(){        System.out.println("After");    }}

3>测试

public class Main {    public static void main(String[] args) throws Exception {       HelloTarget target = new HelloTarget(); 　　　　HelloProxy proxy= new HelloProxy(target);       proxy.sayHello("LZHL");    }}

动态代理

动态代理的代理类是在程序运行期间动态生成的，也有两种实现，一种是JDK动态代理，一种是CGLib动态代理

1》JDK动态代理(基于接口实现，与目标类实现相同接口，从而保证功能一致)

/** * @Author LZHL * @Create 2017-02-19 12:46 * @Description */public class Main {    public static void main(String[] args){

final HelloImpl target = new HelloImpl();

Object proxyInstance = Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), new InvocationHandler() {            /*             * proxy: 代理对象             * method: 目标对象的方法对象             * args: 目标对象方法的参数             * return: 目标对象方法的返回值             */            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {                System.out.println("before");                Object retValue = method.invoke(target, args);                System.out.println("after");                return retValue;            }        });        Hello proxy = (Hello) proxyInstance;        proxy.say("LYX");

//可以把InvocationHandler提取出来，单独写一个类，为了方便大家看，这里我用内部类的形式

        class JDKProxy implements InvocationHandler {            private Object target;            public JDKProxy(Object target){                this.target = target;            }            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {                before();                Object result = method.invoke(target, args);                after();                return result;            }            private void before(){                System.out.println("Before");            }            private void after(){                System.out.println("After");            }        }        InvocationHandler ih = new JDKProxy(target);        Object proxyInstance2 = Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), ih);        Hello proxy2 = (Hello) proxyInstance2;        proxy2.say("LZHL");    }}

2》CGLib动态代理(基于目标类，通过继承目标类，从而保证功能一致)，需要导入cglib-3.2.4.jar包

pom.xml

<dependencies>    <!-- https://mvnrepository.com/artifact/cglib/cglib -->    <dependency>        <groupId>cglib</groupId>        <artifactId>cglib</artifactId>        <version>3.2.4</version>    </dependency>

</dependencies>

1)目标类

public class Hi {    public void sayHi(String msg){        System.out.println("Hi,"+msg);    }}

2)测试

/** * @Author LZHL * @Create 2017-02-19 13:19 * @Description */public class Main {    public static void main(String[] args) {        Enhancer enhancer = new Enhancer();        //设置父类        enhancer.setSuperclass(Hi.class);        //设置回调函数        enhancer.setCallback(new MethodInterceptor() {            public Object intercept(Object target, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {                System.out.println("before");                Object retValue = methodProxy.invokeSuper(target, args);                System.out.println("after");                return retValue;            }        });        Object proxy = enhancer.create();        Hi hi = (Hi) proxy;        hi.sayHi("LXY");

//可以把MethodInterceptor提取出来，单独写一个类，为了方便大家看，这里我用内部类的形式        class CGLibProxy implements MethodInterceptor {

public <T> T getProxy(Class<T> clazz){                return (T) Enhancer.create(clazz, this);            }            public Object intercept(Object target, Method method, Object[] args, MethodProxy proxy) throws Throwable {                before();                Object result = proxy.invokeSuper(target, args);                after();                return result;            }            private void before(){                System.out.println("Before");            }            private void after(){                System.out.println("After");            }        }

CGLibProxy cgLibProxy = new CGLibProxy();        Hi hi2 = cgLibProxy.getProxy(Hi.class);        hi2.sayHi("LZHL");    }}