java的web程序经常出现中文乱码的问题，用一个实现了Filter接口的过滤器类可以较好地解决这个问题。

方式一 EncodingFilter

import java.io.IOException;
import javax.servlet.*;

public class EncodingFilter implements Filter {

private FilterConfig filterConfig =
null;
    private String encoding = null;

@Override
    public void destroy() {
         filterConfig = null;
         encoding = null;
     }

@Override
    public void doFilter(ServletRequest
request, ServletResponse response,
             FilterChain filterChain)
throws IOException, ServletException {
        if
(request.getCharacterEncoding() == null) {
            if (encoding != null) {
                
request.setCharacterEncoding(encoding);
             }
            
filterChain.doFilter(request, response);
         }
     }

@Override//初始化的时候就去web.xml配置文件中拿到对应编码格式
    public void init(FilterConfig
filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
        this.encoding =
filterConfig.getInitParameter("encoding");
     }
}

web.xml中配置

<filter>
     
<filter-name>EncodingFilter</filter-name>
     
<filter-class>EncodingFilter</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>

方式二

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.*;

public class WordFilter implements Filter {

public void destroy() {
// TODO Auto-generated method stub

}

@SuppressWarnings("unchecked")
public void doFilter(ServletRequest req, ServletResponse res,
　　FilterChain chain) throws IOException, ServletException {
　　HttpServletRequest request=(HttpServletRequest)req;
　　HttpServletResponse response=(HttpServletResponse)res;
　　if(request.getMethod().equalsIgnoreCase("get")){//get提交方式
　　　　Enumeration em=request.getParameterNames();
　　　　while(em.hasMoreElements()){
　　　　　　String name=em.nextElement().toString();
　　　　　　String[] values=request.getParameterValues(name);
　　　　　　for(int i=0;i<values.length;i++){
　　　　　　　　values[i]=new String(values[i].getBytes("iso-8859-1"),"utf-8");//把所有字符都转换为指定的编码格式
　　　　　　}
　　　　}
　　}else{
　　　　request.setCharacterEncoding("utf-8");
　　}
　　chain.doFilter(request, response);
}

　　public void init(FilterConfig arg0) throws ServletException {
　　　　// TODO Auto-generated method stub

　　}

}

web.xml中配置

<filter>
<filter-name>WordFilter</filter-name>
<filter-class>filter.WordFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>WordFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>