解决tomcat7中request会对中文重新编码，导致后台接收到为encode编码后参数问题

package xxx;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
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;

public class SetCharacterEncodingFilter implements Filter{
    String encoding = null;
    FilterConfig filterConfig = null;

/** 初始化方法 */
public void init(FilterConfig filterConfig) throws ServletException {
    this.filterConfig = filterConfig;
    this.encoding = filterConfig.getInitParameter("encoding");
}

/** 过滤处理方法 */
public void doFilter(ServletRequest request, ServletResponse response,
        FilterChain chain) throws IOException, ServletException {
    if (encoding!=null){
        //对请求进行编码设置
        request.setCharacterEncoding(encoding);
        HttpServletRequest httprequest=(HttpServletRequest) request;
        if(httprequest.getMethod().equalsIgnoreCase("get")){
            MyRequest myRequest = new MyRequest(httprequest);
            myRequest.setEncoding(encoding);

            chain.doFilter(myRequest, response);
        }else{
            //将处理权转交给下一个处理器
            chain.doFilter(request,response);
        }
    }else{
        //将处理权转交给下一个处理器
        chain.doFilter(request,response);
    }
}

/**
 * Wrapper包装类，装饰设计模式,内部有个真实对象的引用
 */
class MyRequest extends HttpServletRequestWrapper{
    private HttpServletRequest request;
    private String encoding;

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

    public void setEncoding(String encoding) {
        this.encoding = encoding;
    }

    @Override
    //重写父类的方法
    public String getParameter(String name) {
        String[] p = getParameterMap().get(name);
        if(p!=null&&p.length>0){
            return p[0];
        }else{
            return null;
        }
    }

    @Override
    //获取参数的方法
    public Map<String, String[]> getParameterMap() {
        //获取客户端传过来的参数数据，并且包装成一个Map集合
        Map<String, String[]> resMap = new HashMap<String, String[]>();
        Map map = request.getParameterMap();
        Set set = map.keySet();
        Iterator it = set.iterator();
        while(it.hasNext()){
            String key=(String) it.next();
            Object value= map.get(key);
            if(value instanceof String[]){
                String[] values=(String[]) value;
                for(int i=0;i<values.length;i++){
                    try {
                        values[i] = java.net.URLDecoder.decode(values[i], encoding);
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }  //翻页参数中的中文解码，编码在dbpage.java中进行的
                }

                resMap.put(key, values);
            }
        }
        return resMap;
    }
}

/** 销毁方法 */
public void destroy() {
    this.encoding = null;
    this.filterConfig = null;
}}