代理

代理的模式分为3种：
静态代理，动态代理，Cglib代理

今天说说静态代理，
动态代理，主要用于字符编码
Cglib代理：没有使用过

在Spring的AOP编程中:
如果加入容器的目标对象有实现接口,用JDK代理，也即是动态代理
如果目标对象没有实现接口,用Cglib代理

静态代理的实现
首先写个接口

public interface agentInterface {
      public void dealTask(String taskName);   
}

第二步：委托类
public class realclass  implements agentInterface{

    
    @Override
    public void dealTask(String taskName) {
    System.out.print("正在处理任务"+taskName);
    try {
        Thread.sleep(500);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
        
    }

}
第三步：代理类
public class proxyClass implements agentInterface {
    //代理类对于委托类的引用。  
    private realclass real;
    public proxyClass(realclass real) {
        this.real=real;
    }

    @Override
    public void dealTask(String taskName) {
          long stime = System.currentTimeMillis();   
          //将请求分派给委托类处理  
          real.dealTask(taskName);  
          long ftime = System.currentTimeMillis();   
          System.out.println("执行任务耗时"+(ftime - stime)+"毫秒");  
            
        
    }

}
第四步：工厂类
public class staticFactory {

    public static agentInterface    getInstance(){
          return new proxyClass(new realclass());  
    }

}

第五步：测试类

public class clients {

    public static void main(String args[])
    {
        agentInterface proxy = staticFactory.getInstance();
        proxy.dealTask("linking!!!!!!!!!!!");
    }
}

动态代理:字符编码

过滤类
public class GetPostEncodingFilter implements Filter {
    public void destroy() {
    }
    public void doFilter(ServletRequest req, ServletResponse res,FilterChain chain) throws IOException, ServletException {
        //强转
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;
        //创建普通类
        RequestProxy requestProxy = new RequestProxy(request);
        //设置响应类型与编码
        response.setContentType("text/html;charset=UTF-8");
        //发行请求，进入GetPostServlet
        chain.doFilter(requestProxy.getProxy(),response);
    }
    public void init(FilterConfig filterConfig) throws ServletException {
    }
}

代理类
/**
 * @author Administrator
 * 用于产生HttpServletRequest的动态代理对象
 */
class RequestProxy{
    /**
     * 目标对象
     */
    private HttpServletRequest request;
    /**
     * 通过构造器为request设置值
     */
    public RequestProxy(HttpServletRequest request) {
        this.request = request;
    }
    /**
     * 产生HttpServletRequest的代理对象(重点)
     */
    public HttpServletRequest getProxy(){
        return (HttpServletRequest)Proxy.newProxyInstance(
                this.getClass().getClassLoader(), 
                request.getClass().getInterfaces(), 
                new InvocationHandler(){
                    public Object invoke(Object proxy, Method method,Object[] args) throws Throwable {
                        Object returnValue = "";
                        String methodName = method.getName();
                        if("getParameter".equals(methodName)){
                            //获取客户端请求的类型
                            String requestType = request.getMethod();
                            //如果是GET请求的话
                            if("GET".equals(requestType)){
                                //获取表单提交的用户名和性别
                                String temp = (String) method.invoke(request,args);
                                //如果非空
                                if(temp!=null && temp.trim().length()>0){
                                    //转还
                                    byte[] buf = temp.getBytes("ISO8859-1");
                                    //手工装配
                                    returnValue = new String(buf,"UTF-8");
                                }
                            //如果是POST请求的话
                            }else if("POST".equals(requestType)){
                                //设置编码方式
                                request.setCharacterEncoding("UTF-8");
                                //获取表单提交的用户名和性别
                                returnValue = method.invoke(request,args);
                            }
                        }else{
                            returnValue = method.invoke(request,args);
                        }
                        return returnValue;
                    }
                });
    }
}