3种代理的实现

摘要笔记：代理实现了方法的扩充。代理都要实现接口，static--被代理类的接口；

dynamic--InvocationHandler，实现invoke方法创建对象object传给method.invoke(object,orgs)--执行代理方法；

CGLIB--MethodInterceptor,创建对象object并重写intercept方法，通过method.invoke--执行代理。

接口

//Person.java
1 package heqing.spring.proxy;
2 
3 public interface Person {    
4     public void say();
5 }

具体类

 //Student.java
 1 package heqing.spring.proxy;
 2 
 3 public class Student implements Person {
 4     private String sname;
 5     public Student() {
 6         sname="Student";
 7     }
 8     public void say() {
 9         System.out.println("My name is "+sname+",I'm a student");
10     }
11 }

//Teacher.java
　package heqing.spring.proxy;
1 public class Teacher implements Person {
2     private String tname;
3     public Teacher() {
4         tname="teacher";
5     }
6     public void say() {
7         System.out.println("My name is "+tname+",I'm a teacher");
8     }
9 }

静态代理，动态代理，CGLIB代理

//StaticProxy
 1 package heqing.spring.proxy;
 2 
 3 public class StaticProxy implements Person {
 4     private Person person;
 5     public StaticProxy(Person person) {
 6         this.person=person;
 7     }
 8     @Override
 9     public void say() {
10         System.out.println("I'm StaticProxy.");
11         person.say();
12         System.out.println("I'm over Excute");
13     }
14 }

 //DynamicProxy.java
 1 package heqing.spring.proxy;
 2 
 3 import java.lang.reflect.InvocationHandler;
 4 import java.lang.reflect.Method;
 5 import java.lang.reflect.Proxy;
 6 
 7 public class DynamicProxy implements InvocationHandler {
 8     private Object obj;
 9     public Object createInstance(Object obj){
10         this.obj=obj;
11         return Proxy.newProxyInstance(obj.getClass().getClassLoader(), obj.getClass().getInterfaces(), this);
12     }
13     
14     @Override
15     public Object invoke(Object proxy, Method method, Object[] args)
16             throws Throwable {
17         System.out.println("I'm DynamicProxy");
18         Object result=method.invoke(obj, args);
19         return null;
20     }
21 }

 //CGLIBProxy.java
 1 package heqing.spring.proxy;
 2 
 3 import java.lang.reflect.Method;
 4 
 5 import net.sf.cglib.proxy.Enhancer;
 6 import net.sf.cglib.proxy.MethodInterceptor;
 7 import net.sf.cglib.proxy.MethodProxy;
 8 
 9 public class CGLIBProxy implements MethodInterceptor {
10     Object obj;
11     public Object createInstance(Object object){
12         obj=object;
13         Enhancer enchaner=new Enhancer();
14         enchaner.setSuperclass(obj.getClass());
15         enchaner.setCallback(this);
16         return enchaner.create();
17     }
18     @Override
19     public Object intercept(Object Proxy, Method method, Object[] args,
20             MethodProxy methodProxy) throws Throwable {
21         System.out.println("I'm MethodInterceptor");
22         Object result=method.invoke(obj, args);
23         System.out.println(method.getName());
24         return result;
25     }
26 }

测试类

1 //TestStaticProxy.java
2 package heqing.spring.proxy;
3 
4 public class TestStaticProxy {
5     public static void main(String[] args) {
6         StaticProxy sp=new StaticProxy(new Student());
7         sp.say();
8     }
9 }

 1 //TestDynamicProxy.java
 2 package heqing.spring.proxy;
 3 
 4 public class TestDynamicProxy {
 5     public static void main(String[] args) {
 6         DynamicProxy dynamicProxy=new DynamicProxy();
 7         Person t=(Person)dynamicProxy.createInstance(new Student());
 8         t.say();        
 9     }
10 }

 1 //TestCGLIBProxy.java
 2 package heqing.spring.proxy;
 3 
 4 public class TestCGLIBProxy {
 5     public static void main(String[] args) {
 6         CGLIBProxy proxy=new CGLIBProxy();
 7         Person person=(Person)proxy.createInstance(new Teacher());
 8         person.say();
 9     }
11 }