JAVA WEB 解决编码问题的filter

最近使用Springmvc，GET传输参数的时候，经常出错误，下面介绍添加一个Filter的方法，可以解决这个问题。既支持POST方式也支持GET方式。

首先写一个Filter

package com.qunar.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 CharacterEncodingFilter implements Filter {
    private String encode = "UTF-8";// 默认UTF-8编码

    public void init(FilterConfig filterConfig) throws ServletException {
        String encoding = filterConfig.getInitParameter("encode");
        if (encoding != null) {
            encode = encoding;
        }
    }

    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;
        // 设置request编码
        request.setCharacterEncoding(encode);
        // 设置相应信息
        response.setContentType("text/html;charset=" + encode);
        response.setCharacterEncoding(encode);
        chain.doFilter(new CharacterEncodingRequest(request), response);
    }

    public void destroy() {

    }

}

/**
 * 对Get方式传递的请求参数进行编码
 */
class CharacterEncodingRequest extends HttpServletRequestWrapper {
    private HttpServletRequest request = null;

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

    /**
     * 对参数重新编码
     */
    @Override
    public String getParameter(String name) {
        String value = super.getParameter(name);
         if(value == null)
               return null;
         String method = request.getMethod();
        if ("get".equalsIgnoreCase(method)) {
            try {
                value = new String(value.getBytes("ISO8859-1"), request.getCharacterEncoding());
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        return value;
    }

}

然后在xml里面添加这个filter

<filter>
      <filter-name>characterEncodingFilter</filter-name>
      <filter-class>com.qunar.filter.CharacterEncodingFilter</filter-class>
      <init-param>
          <param-name>encode</param-name>
          <param-value>UTF-8</param-value>
      </init-param>
  </filter>
  <filter-mapping>
      <filter-name>characterEncodingFilter</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>

当然有一些人为了单纯解决GET的编码问题，修改整个站点的编码，直接修改Connector也可以。

<Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443" URIEncoding="UTF-8"/>