过滤器报java.lang.ClassCastException

Question

写了个过滤器，怎么报
java.lang.ClassCastException: com.test.ComFilter cannot be cast to javax.servlet.Servletimport 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 ComFilter implements Filter<servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>ComFilter</servlet-name>
    <servlet-class>com.test.ComFilter</servlet-class>
  <init-param>
   <param-name>encoding</param-name>
   <param-value>GBK</param-value>
　</init-param>
　<init-param>
　　<param-name>ignore</param-name>
　　<param-value>true</param-value>
　</init-param>
</servlet>
<servlet-mapping>
  　<servlet-name>ComFilter</servlet-name>
  　<url-pattern>/*</url-pattern>
</servlet-mapping>  

Answer 1

你实现servlet接口或者继承HtppServelt类了吗？

Answer 2

package com.test;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 ComFilter implements Filter {
protected String encoding = null; 
protected FilterConfig filterConfig = null; 
protected boolean ignore = true; //在web.xml文件里定义filter时要用到此参数 public void destroy() {
         this.encoding = null;
         this.filterConfig = null;
} public void doFilter(ServletRequest request, ServletResponse response,
    FilterChain chain) throws IOException, ServletException {
        if (ignore || (request.getCharacterEncoding() == null)) {
            String encoding = selectEncoding(request);
            if (encoding != null)
                request.setCharacterEncoding(encoding);
        }
        chain.doFilter(request, response);
} public void init(FilterConfig filterConfig) throws ServletException {
   this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
        String value = filterConfig.getInitParameter("ignore");
        if (value == null)
            this.ignore = true;
        else if (value.equalsIgnoreCase("true"))
            this.ignore = true;
        else if (value.equalsIgnoreCase("yes"))
            this.ignore = true;
        else
            this.ignore = false;
}     protected String selectEncoding(ServletRequest request) {
        return (this.encoding);
    } }

Answer 3

你建过滤器，为什么配置文件是 servlet 呢？

Answer 4

<servlet>
    <description>This is the description of my J2EE component </description>
    <display-name>This is the display name of my J2EE component </display-name>
    <servlet-name>ComFilter </servlet-name>
    <servlet-class>com.test.ComFilter </servlet-class>
  <init-param>
  <param-name>encoding </param-name>
  <param-value>GBK </param-value>
　 </init-param>
　 <init-param>
　　 <param-name>ignore </param-name>
　　 <param-value>true </param-value>
　 </init-param>
</servlet>
<servlet-mapping>
  　 <servlet-name>ComFilter </servlet-name>
  　 <url-pattern>/* </url-pattern>
</servlet-mapping> 把红色部分改成 filter 就 OK 啦  

Answer 5

呵呵，你的配置文件写错了，火龙果说的对
<filter>
    <filter-name>ComFilter</filter-name>//依次更换
    <filter-class>com.test.ComFilter </filter-class>
</filter>
<filter-mapping>
    <fileter-name>ComFilter</filter-name>
    <url-pattern>/*</pattern>
</filter-mapping>重启服务器，ok

Answer 6

我的是写的filter啊，但是还是报同样的错啊