老师您好,在练习时重定向到getRequestData页面一直提示404,麻烦帮忙看下是什么原因导致的,谢谢!
package com.itbaizhan.filter;
import javax.servlet.*;
import java.io.IOException;
/**
 * 设置请求编码过滤器
 */
public class EncodingFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //设置请求编码
        servletRequest.setCharacterEncoding("utf-8");
        filterChain.doFilter(servletRequest,servletResponse);
    }
    @Override
    public void destroy() {
    }
}<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <form action="/getRequestData.do" method="post">
        用户名:<input type="text" name="username"/><br/>
        密码:<input type="password" name="userpwd"/><br/>
        爱好:<input type="checkbox" name="userlike" value="Sport"/>体育
             <input type="checkbox" name="userlike" value="Music"/>音乐
             <input type="checkbox" name="userlike" value="Art"/>艺术<br/>
        <input type="submit" value="OK">
    </form>
</body>
</html>
<servlet>
    <servlet-name>getRequestDataServlet</servlet-name>
    <servlet-class>com.itbaizhan.GetRequestDataServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>getRequestDataServlet</servlet-name>
    <url-pattern>/getRequestData.do</url-pattern>
</servlet-mapping>
package com.itbaizhan;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
public class GetRequestDataServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //设置请求编码
       // req.setCharacterEncoding("utf-8");
        //获取用户名
        String username = req.getParameter("username");
        System.out.println(username);
        //设置请求编码2
        /*String name=new String(username.getBytes("ISO-8859-1"),"UTF-8");
        System.out.println(name);*/
        //获取用户密码
        String userpwd = req.getParameter("userpwd");
        //获取复选框的值
        String[] userlikes = req.getParameterValues("userlike");
        List<String> list= Arrays.asList(userlikes);
        //获取表单中的所有keys
        Enumeration<String> parameterNames = req.getParameterNames();
        List<String> paralist=new ArrayList<>();
        while(parameterNames.hasMoreElements()){
            paralist.add(parameterNames.nextElement());
        }
        //使用Map结构获取提交数据
        Map<String, String[]> parameterMap = req.getParameterMap();
        Iterator<Map.Entry<String,String[]>> iterator =parameterMap.entrySet().iterator();
        resp.setContentType("text/plain;charset=utf-8");
        PrintWriter pw = resp.getWriter();
        pw.println("UserName:"+username);
        pw.println("PassWord:"+userpwd);
        pw.println("UserLike:"+list);
        pw.println("Names:"+paralist);
        while(iterator.hasNext()){
            Map.Entry<String,String[]> entry=iterator.next();
            String key=entry.getKey();
            String[] value=entry.getValue();
            pw.println(key+"="+Arrays.asList(value));
        }
        pw.flush();
        pw.close();
    }
}