过滤全网乱码

filter类里写代码

包装类思想

package cn.itcast.filter;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

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.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

public class AllCharacterEncodingFilter implements Filter {
    private FilterConfig filterConfig;
    
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }
    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)req;
        HttpServletResponse response = (HttpServletResponse)resp;
        //获取配置的过滤器参数encoding的值：如果没有，给定一个默认值
        String encoding = filterConfig.getInitParameter("encoding");
        if(encoding==null)
            encoding = "UTF-8";
        //设置POST请求方式的中文请求参数的编码
        request.setCharacterEncoding(encoding);
        //设置响应输出时的编码：字符流和字节流
        response.setCharacterEncoding(encoding);//字节流输出时通知客户端的解码码表
        response.setContentType("text/html;charset="+encoding);//字节流输出时通知客户端的解码码表；字符流：字符流输出时使用的码表及通知客户端解码用的码表
        
        MyHttpServletRequest mrequest = new MyHttpServletRequest(request);
        //放行
        chain.doFilter(mrequest, response);
    }

    
    public void destroy() {

    }
}

//HttpServletRequestWrapper内部的代码与连接池原理中那个默认适配器一样
class MyHttpServletRequest extends HttpServletRequestWrapper{
    public MyHttpServletRequest(HttpServletRequest request){
        super(request);
    }
    //只对get请求方式进行改写
    public String getParameter(String name) {
        String value = super.getParameter(name);
        if(value==null)
            return value;
        //得到请求方式
        String method = super.getMethod();
        if("get".equalsIgnoreCase(method)){
            try {
                value = new String(value.getBytes("ISO-8859-1"),super.getCharacterEncoding());
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        return value;
    }
    
}
class MyHttpServletRequest1 extends HttpServletRequestWrapper{
    private HttpServletRequest request;
    public MyHttpServletRequest1(HttpServletRequest request){
        super(request);
        this.request = request;
    }
    //只对get请求方式进行改写
    public String getParameter(String name) {
        String value = request.getParameter(name);
        if(value==null)
            return value;
        //得到请求方式
        String method = request.getMethod();
        if("get".equalsIgnoreCase(method)){
            try {
                value = new String(value.getBytes("ISO-8859-1"),"UTF-8");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        return value;
    }
    
}

动态代理类思想

package cn.itcast.web.bbs.mvc.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.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class EncodingFilter implements Filter {

    public EncodingFilter() {
    }

    public void destroy() {
    }

    /**
     * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest req=(HttpServletRequest) request;
        HttpServletResponse res=(HttpServletResponse) response;
        RequestProxy requestProxy=new RequestProxy(req);
        HttpServletRequest xx=requestProxy.getRequestProxy();
        chain.doFilter(xx, response);
    }

    public void init(FilterConfig fConfig) throws ServletException {
    }
}
class RequestProxy
{
    private HttpServletRequest request;
    public RequestProxy(HttpServletRequest request) {
        super();
        this.request = request;
    }
    //产生动态代理对象
    public HttpServletRequest getRequestProxy()
 {
        return (HttpServletRequest) Proxy.newProxyInstance(RequestProxy.class
                .getClassLoader(), request.getClass().getInterfaces(),
                new InvocationHandler() {
                    @Override
                    public Object invoke(Object proxy, Method method,
                            Object[] args) throws Throwable {
                        Object returnValue="";
                        String methodName=method.getName();
                        if(methodName.equals("getParameter"))
                        {
                            String methodType=request.getMethod();
                            if("GET".equalsIgnoreCase((methodType)))
                            {//乱码
                                String temp = (String) method.invoke(request,args);
                                //还原
                                byte[] buf = temp.getBytes("ISO8859-1");
                                //正码
                                returnValue = new String(buf,"UTF-8");
                            }
                            else if("POST".equalsIgnoreCase(methodType))
                            {
                                request.setCharacterEncoding("UTF-8");
                                returnValue = method.invoke(request,args);
                            }
                        }
                        else
                        {
                            returnValue=method.invoke(request, args);
                        }
                        return returnValue;
                    }
                });
    }
    
}