Filter学习

EncodeFilter，实现类如下

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 EncodeFilter implements Filter{
private FilterConfig config=null;
private String encoding = null;

public void destroy() {
this.config = null;
this.encoding = null;
}

public void doFilter(ServletRequest request,
   ServletResponse response,
   FilterChain chain) throws IOException, ServletException {

String encoding = selectEncoding(request);
    if (encoding != null) {
        request.setCharacterEncoding(encoding);
    }
chain.doFilter(request, response);

}

public void init(FilterConfig config) throws ServletException {
this.config = config;
this.encoding = config.getInitParameter("encoding");
}

protected String selectEncoding(ServletRequest request) {
return (this.encoding);
}

}



Web.xml配置如下，直接访问.jsp或者.do文件，即可进行编码转换
<filter>
      <filter-name>Encoding</filter-name>
      <filter-class>pocketbook.filterTest.EncodeFilter</filter-class>
      <init-param>
         <param-name>encoding</param-name>
         <param-value>utf-8</param-value>
      </init-param>
   </filter>
  <filter-mapping>
      <filter-name>Encoding</filter-name>
      <servlet-name>action</servlet-name>
   </filter-mapping>
   <filter-mapping>
      <filter-name>Encoding</filter-name>
      <url-pattern>*.jsp</url-pattern>
   </filter-mapping>

<servlet>
      <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
</servlet>

<servlet-mapping>
      <servlet-name>action</servlet-name>
      <url-pattern>*.do</url-pattern>
</servlet-mapping>