import javax.servlet.http.HttpServlet;
     import javax.servlet.Filter;
     import javax.servlet.FilterConfig;
     import javax.servlet.ServletException;
     import javax.servlet.ServletRequest;
     import javax.servlet.ServletResponse;
     import javax.servlet.FilterChain;
     import javax.servlet.http.*;
     import java.io.IOException;
     public class CharacterEncodingFilter
       extends HttpServlet
       implements Filter {

       private FilterConfig filterConfig;
       private String targetEncoding = "ASCII";

     /**
      * Called by the web container to indicate to a filter that it is being placed
      * into service.
      *
      * @param filterConfig FilterConfig
      * @throws ServletException
      * @todo Implement this javax.servlet.Filter method
     */
      public void init(FilterConfig filterConfig) throws ServletException {
      this.filterConfig = filterConfig;
      this.targetEncoding = filterConfig.getInitParameter("encoding");
     }

    /**
     * The <code>doFilter</code> method of the Filter is called by the container
     * each time a request/response pair is passed through the chain due to a
     * client request for a resource at the end of the chain.
     *
     * @param request ServletRequest
     * @param response ServletResponse
     * @param chain FilterChain
     * @throws IOException
     * @throws ServletException
     * @todo Implement this javax.servlet.Filter method
     */
     public void doFilter(ServletRequest srequest, ServletResponse sresponse,
                       FilterChain chain) throws IOException, ServletException {
      try {
        HttpServletRequest request = (HttpServletRequest) srequest;
        request.setCharacterEncoding(targetEncoding);
        chain.doFilter(srequest, sresponse);
          }
      catch (ServletException sx) {
         filterConfig.getServletContext().log(sx.getMessage());
          }
      catch (IOException iox) {
         filterConfig.getServletContext().log(iox.getMessage());
        }
      }

    /**
     * Called by the web container to indicate to a filter that it is being taken
     * out of service.
     *
     * @todo Implement this javax.servlet.Filter method
     */
     public void destroy() {
       filterConfig = null;
       targetEncoding = null;
     }
  }
  
  3.config web.xml
    attention: add these to your web.xml
     <filter>
     <filter-name>EncodingFilter</filter-name>
     <filter-class>com.victory.util.CharacterEncodingFilter</filter-class>
     <init-param>
       <param-name>encoding</param-name>
       <param-value>UTF-8</param-value>
     </init-param>
    </filter>
    <filter-mapping>
    <filter-name>EncodingFilter</filter-name>
     <url-pattern>/*</url-pattern>
    </filter-mapping> 
  4.set database configration
     modify the file:    my.ini
     [client]     default-character-set=utf8 
     [mysqld]  default-character-set=utf8
  5.restart Mysql server
  6.modified your table coding way to utf8
     or ceate your table like this :
     CREATE TABLE `user` (
    `ID` int(11) NOT NULL auto_increment,
    `USERNAME` varchar(50) NOT NULL default '',
    `PASSWORD` varchar(50) NOT NULL default '',
     PRIMARY KEY  (`ID`)
     ) ENGINE=MyISAM DEFAULT CHARSET=utf8; 
  7.restrart your tomcat sever

   OK,it's all.

   Authrougn I have sovled   my problem, I think I  don't have enough understanding for it,  So hope    communicate with you! 

   Attention:mess code also exist in your database,through page hasn't mess code.