利用filter和动态代理解决全站乱码问题

package com.baowei.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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CharctorFilter implements Filter {

    @Override
    public void destroy() {

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("utf-8");

        chain.doFilter(new MyRequest(request).getProxyRequset(), response);

    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    class MyRequest implements InvocationHandler {
        private HttpServletRequest request;

        public MyRequest(HttpServletRequest request) {
            this.request = request;
        }

        // 返回增强后的代理对象
        public HttpServletRequest getProxyRequset() {
            return (HttpServletRequest) Proxy.newProxyInstance(request
                    .getClass().getClassLoader(), request.getClass()
                    .getInterfaces(), this);
        }

        // 对真实request对象的getparameter进行增强
        @Override
        public Object invoke(Object proxy, Method method, Object[] args)
                throws Throwable {
            if (!method.getName().equals("getParameter")) {
                return method.invoke(request, args);
            }
            if (!((HttpServletRequest) request).getMethod().equalsIgnoreCase(
                    "get")) {
                return method.invoke(request, args);
            }

            String value = (String) method.invoke(request, args);
            if (value == null) {
                return null;
            }

            return new String(value.getBytes("iso8859-1"), "UTF-8");

        }

    }

} 

<filter>
        <filter-name>CharctorFilter</filter-name>
        <filter-class>com.baowei.filter.CharctorFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>CharctorFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>