How does the java Filter handle Chinese garbled characters?

//过滤器类
CharactorFilter.jsp
package cn.com.Filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class CharactorFilter implements Filter { //继承Filter类
    //字符编码
    String encoding=null;
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        if(encoding!=null){
        //设置request字符编码
            request.setCharacterEncoding(encoding);
         //设置response字符编码
            response.setContentType("text/html;charset="+encoding);
        }
     //传递给下一个过滤器
        chain.doFilter(request, response);
    }
    public void init(FilterConfig filterConfig) throws ServletException {
      //获取初始化参数
        encoding=filterConfig.getInitParameter("encoding");
    }
    public void destroy() {
        // TODO Auto-generated method stub
        encoding=null;
    }
}

<filter>      <!--注意这里是filter，不要配置成servlet-->
    <filter-name>CharactorFilter</filter-name>    <!--过滤器名称-->
   <filter-class>cn.com.Filter.CharactorFilter</filter-class>  <!--过滤器的完整类名-->  
     <init-param>   <!--初始化参数-->  
         <param-name>encoding</param-name>  <!--参数名称-->  
         <param-value>utf-8</param-value>   <!--参数值-->  
     </init-param>
  </filter>
  <filter-mapping> <!--过滤器映射--> 
      <filter-name>CharactorFilter</filter-name><!--过滤器名称-->   
      <url-pattern>/*</url-pattern><!--URL映射，给所有页面处理乱码-->  
      </filter-mapping>