【WEB小工具】EncodingFilter—设置全局编码

　　1.我们知道，如果是POST请求，我们需要调用request.setCharacterEncoding("utf-8")

方法来设计编码。

 public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
          request.setCharacterEncoding("gbk");  //只适用于post提交，不适用于get
          response.setCharacterEncoding("gbk");
     }

　　2.如果是GET请求，我们需要自己手动来处理编码问题。

　　3.如果我们使用了EncodingFilter，那么就处理了POST和GET请求的编码问题。

修改web.xml:

<!-- 处理全站请求编码。无论是GET还是POST,默认是UTS-8 -->
<filter>
    <filter-name>EncodingFilter</filter-name>
    <filter-class>cn.itcast.filter.EncodingFilter</filter-class>
    <init-param>
        <param-name>charset</param-name>
        <param-value>utf-8</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>EncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

EncodingFilter() 类源代码：

 package cn.itcast.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;
 import javax.servlet.http.HttpServletRequest;

 public class EncodingFilter implements Filter {
     private String charset = "UTF-8";
     @Override
     public void destroy() {}

     @Override
     public void doFilter(ServletRequest request, ServletResponse response,
             FilterChain chain) throws IOException, ServletException {
         HttpServletRequest req = (HttpServletRequest) request;
         if(req.getMethod().equalsIgnoreCase("GET")) {
             if(!(req instanceof GetRequest)) {
                 req = new GetRequest(req, charset);//澶勭悊get璇锋眰缂栫爜
             }
         } else {
             req.setCharacterEncoding(charset);//澶勭悊post璇锋眰缂栫爜
         }
         chain.doFilter(req, response);
     }

     @Override
     public void init(FilterConfig fConfig) throws ServletException {
         String charset = fConfig.getInitParameter("charset");
         if(charset != null && !charset.isEmpty()) {
             this.charset = charset;
         }
     }
 }