个人关于web2.5中的动态反射代理来解决sevlet中文乱码理解

第一部分：Filter(手动在web.xml中配制Filter)

package com.sml.web.filter;

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

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 在filter中就先处理乱码问题
 * jdk中的动态代理 proxy 
 * fliter
 *服务器的启动而创建
 * 关闭而关闭
 * 
 * @author Administrator
 *
 */
public class Filter4Login implements Filter {

	@Override
	public void destroy() {
		System.out.println("filter销毁了");
	}

	@Override
	public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
			throws IOException, ServletException {

		// 强转
		HttpServletRequest request = (HttpServletRequest) arg0;
		HttpServletResponse response = (HttpServletResponse) arg1;

		// 动态代理
		HttpServletRequest requestProxy = (HttpServletRequest) Proxy.newProxyInstance(
				request.getClass().getClassLoader(), request.getClass().getInterfaces(), new InvocationHandler() {

					@Override
					public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

						if ("getParameter".equals(method.getName())) {

							if ("get".equalsIgnoreCase(request.getMethod())) {
								String s = (String) method.invoke(request, args);

								return new String(s.getBytes("iso-8859-1"), "utf-8");
							} else if ("post".equalsIgnoreCase(request.getMethod())) {
								request.setCharacterEncoding("utf-8");
								return method.invoke(request, args);
							}

						}

						return method.invoke(request, args);
					}
				});
		arg2.doFilter(requestProxy, response);
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
		System.out.println("filter创建了");
	}

}

第二部分:关于servlet

package com.sml.web.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 登录中文乱码问题
 */
public class LoginServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		String username = request.getParameter("username");
		System.out.println(username);

		String hobby = request.getParameter("hobby");
		System.out.println(hobby);

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

	@Override
	public void init() throws ServletException {
		super.init();
		System.out.println("servlet创建了");
	}

	@Override
	public void destroy() {
		super.destroy();
		System.out.println("servlet销毁了");
	}

}