解析通过web.xml文件控制利用过滤器实现编码格式步骤

解析通过web.xml文件控制利用过滤器实现编码格式步骤

过滤类篇：

import java.io.IOException;

 

import javax.servlet.Filter;

import javax.servlet.ServletRequest;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletResponse;

import javax.servlet.FilterChain;

 

//实现javax.servlet.Filter类，强制实现3个方法

public class SetCharacterEncodingFilter implements Filter

{

    String encoding = "";

    //初始化方法

    public void init(FilterConfig filterConfig) throws ServletException

{

    //从web.xml 文件中获取编码格式，参数名为’encoding’

        encoding = filterConfig.getInitParameter("encoding");

        if(encoding==null){//判断，若编码格式为空，赋默认值为GBK

            encoding = "GBK";

       }

}

//执行操作方法

    public void doFilter(ServletRequest request,

                         ServletResponse response,

                         FilterChain chain)

                  throws IOException, ServletException

{

    //判断，若项目中没有设置编码格式时，给予设置

        if (request.getCharacterEncoding() == null)

        {

           //将编码格式设置成获取的参数值

            request.setCharacterEncoding(encoding);

        }

       //设置response的编码格式，

        response.setContentType("text/html; charset="+encoding);

       //将程序继续运行下去

        chain.doFilter(request, response);

}

//销毁方法

public void destroy()

//将编码格式变量清空

    { this.encoding = null; }

}

 

Web.xml文件篇：

<filter>

  <filter-name>aa</filter-name>

    //filter.SetCharacterEncodingFilter为过滤器类路径

  <filter-class>filter.SetCharacterEncodingFilter</filter-class>

  <init-param>//配置过滤器参数

   <param-name>encoding</param-name>//参数名

   <param-value>GBK</param-value>//参数值

  </init-param>

 </filter>

 <filter-mapping>

  <filter-name>aa</filter-name>

  <url-pattern>/*</url-pattern>//过滤器匹配的范围

 </filter-mapping>