代理模式

 * Created by j.tommy on 2017/9/10.
 */
public interface  {
    String request();
}

 * Created by j.tommy on 2017/9/10.
 */
public class UserService implements  {
    
    public String request() {
        return "hello";
    }
}

 * Created by j.tommy on 2017/9/10.
 */
public class Main {
    public static void main(String[] args) {
        IUserService ius = new UserService();
        String result = ius.request();
        System.out.println("result:" + result);
    }
}

 * Created by j.tommy on 2017/9/10.
 */
public class UserServiceProxy implements  {
    private UserService us = null;
    
    public String request() {
        // 延迟加载us的实例，在实际使用时初始化
        if (null == us) {
            us = new UserService();
            System.out.println("Created UserService.");
        }
        return us.request();
    }
}

 * Created by j.tommy on 2017/9/10.
 */
public class Main {
    public static void main(String[] args) {
        // 通过代理类调用
        IUserService ius = new UserServiceProxy();
        System.out.println("Created proxy.");
        String result = ius.request();
        System.out.println("result:" + result);
    }
}

 * jdk动态代理。
 * Created by j.tommy on 2017/9/10.
 */
public class JdkDynamicProxy implements InvocationHandler {
    // 真实对象
    private Object target;
    public JdkDynamicProxy(Object target) {
        this.target = target;
    }
    
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        // 调用真实对象的方法
        Object result = method.invoke(target,args);
        return result;
    }
    
     * 获取目标对象的代理对象
     * @return
     */
    public Object getProxy() {
        return Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),target.getClass().getInterfaces(),this);
    }
}

 * Created by j.tommy on 2017/9/10.
 */
public class Main {
    public static void main(String[] args) {
        // JDK动态代理
        // 真实对象
        IUserService ius = new UserService();
        // 代理对象
        IUserService us = (IUserService) new JdkDynamicProxy(ius).getProxy();
        String result = us.request();
        System.out.println("result:" + result);
    }
}

 * Created by j.tommy on 2017/9/10.
 */
public class CglibProxy implements MethodInterceptor {
    private Enhancer enhancer = new Enhancer();
    
    public Object intercept(Object o, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
        // 通过代理类调用父类中的方法
        return methodProxy.invokeSuper(o,args);
    }
    public Object getProxy(Class clazz) {
        // 设置需要创建之类的类
        enhancer.setSuperclass(clazz);
        enhancer.setCallback(this);

        // 通过字节码结束创建之类实例
        return enhancer.create();
    }
}

 * Created by j.tommy on 2017/9/10.
 */
public class Main {
    public static void main(String[] args) {
        CglibProxy cp = new CglibProxy();
        UserService ius = (UserService) cp.getProxy(UserService.class);
        String result = ius.request();
        System.out.println("result:" + result);
    }
}