java 代理机制的实例详解

java 代理机制的实例详解

前言：

 java代理分静态代理和动态代理，动态代理有jdk代理和cglib代理两种，在运行时生成新的子类class文件。本文主要练习下动态代理，代码用于备忘。对于代理的原理和机制，网上有很多写的很好的，就不班门弄斧了。

jdk代理

实例代码

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

public class ProxyFactory implements InvocationHandler {

  private Object tarjectObject;

  public Object creatProxyInstance(Object obj) {
    this.tarjectObject = obj;
    return Proxy.newProxyInstance(this.tarjectObject.getClass()
        .getClassLoader(), this.tarjectObject.getClass()
        .getInterfaces(), this);
  }

  @Override
  public Object invoke(Object proxy, Method method, Object[] args)
      throws Throwable {
    Object result = null;
    if (AssessUtils.isAssess()) {
      result = method.invoke(this.tarjectObject, args);
    }else{
      throw new NoAssessException("This server cannot run this service.");
    }
    return result;
  }
}

cglib代理

import java.lang.reflect.Method;
import org.springframework.cglib.proxy.Enhancer;
import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;

public class ProxyCglibFactory implements MethodInterceptor {

  private Object tarjectObject;

  public Object creatProxyInstance(Object obj) {
    this.tarjectObject = obj;
    Enhancer enhancer=new Enhancer();
    enhancer.setSuperclass(this.tarjectObject.getClass());
    enhancer.setCallback(this);
    return enhancer.create();
  }

  @Override
  public Object intercept(Object obj, Method method, Object[] args,
      MethodProxy arg3) throws Throwable {
    Object result = null;
    if (AssessUtils.isAssess()) {
      result = method.invoke(this.tarjectObject, args);
    }else{
      throw new NoAssessException("This server cannot run this service.");
    }
    return result;
  }
}

Aspect注解

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;

@Aspect
public class AssessInterceptor {
  @Pointcut(value="execution (* com..*.*(..))")
  private void anyMethod(){};

  @Before("anyMethod()")
  public void doBefore(JoinPoint joinPoint) throws NoAssessException{
    if (!AssessUtils.isAssess()) {
      throw new NoAssessException("This server cannot run this service.");
    }
  }

  /**
   * Around异常的时候调用
   * @param pjp
   * @throws Throwable
   */
  @Around("anyMethod()")
  public void invoke(ProceedingJoinPoint pjp) throws Throwable{
    pjp.proceed();
  }

}

以上就是java代理机制的实例，如有疑问请留言或者到本站社区交流讨论，感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！

原文链接：http://sheungxin.iteye.com/blog/2346329