Java靜態(tài)代理和動態(tài)代理總結(jié)

更新時間：2017年02月19日 16:36:19 作者：LZHL

這篇文章主要介紹了Java靜態(tài)代理和動態(tài)代理總結(jié),非常不錯，具有參考借鑒價值，需要的朋友可以參考下

靜態(tài)代理

第一種實現(xiàn)(基于接口)：

1》接口

public interface Hello {
 void say(String msg);
}

2》目標類，至少實現(xiàn)一個接口

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

3》代理類(與目標類實現(xiàn)相同接口，從而保證功能一致)

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》測試

/**
 * @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");
 }
}

第二種實現(xiàn)(基于目標類)：

1>目標類

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

2>代理類(通過繼承目標類，保證功能一致)

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>測試

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

動態(tài)代理

動態(tài)代理的代理類是在程序運行期間動態(tài)生成的，也有兩種實現(xiàn)，一種是JDK動態(tài)代理，一種是CGLib動態(tài)代理

1》JDK動態(tài)代理(基于接口實現(xiàn)，與目標類實現(xiàn)相同接口，從而保證功能一致)

/**
 * @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: 代理對象
    * method: 目標對象的方法對象
    * args: 目標對象方法的參數(shù)
    * return: 目標對象方法的返回值
    */
   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提取出來，單獨寫一個類，為了方便大家看，這里我用內(nèi)部類的形式
  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動態(tài)代理(基于目標類，通過繼承目標類，從而保證功能一致)，需要導(dǎo)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)目標類

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

2)測試

/**
 * @Author LZHL
 * @Create 2017-02-19 13:19
 * @Description
 */
public class Main {
 public static void main(String[] args) {
  Enhancer enhancer = new Enhancer();
  //設(shè)置父類
  enhancer.setSuperclass(Hi.class);
  //設(shè)置回調(diào)函數(shù)
  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提取出來，單獨寫一個類，為了方便大家看，這里我用內(nèi)部類的形式
  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");
 }
}

以上所述是小編給大家介紹的Java靜態(tài)代理和動態(tài)代理總結(jié)，希望對大家有所幫助，如果大家有任何疑問歡迎給我留言，小編會及時回復(fù)大家的！

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