小弟新手，学习javaweb编程，用了servlet&JSP学习笔记，写了书上的一个例子，eclipse和tomcat共同开发，其他配置都好着，跑一个当下时间的servlet程序也能显示，但是书上例子不知为啥无法显示，还显示400错误，求大神解答，顺便希望大神推荐几本学习javaweb开发的经典书籍，这样也能学习提高。
package Demoservlerequest;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/Demorequestheader")
public class Demorequestheader extends HttpServlet {
private static final long serialVersionUID = 1L;
public Demorequestheader()
{
super();
}
public void processRequest(HttpServletRequest request,
HttpServletResponse response)throws ServletException,IOException
{
response.setContentType("text/html;charset= UTF-8");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet ShowHeader</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Servlet ShowHeader at"+
request.getContextPath()+"</h1>");
Enumeration e = request.getHeaderNames();
while(e.hasMoreElements())
{
String param= (String) e.nextElement();
out.println(param+":"+request.getHeader(param)+"<br>");
}
out.println("</body>");
out.close();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
processRequest(request,response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
processRequest(request,response);
}
}
路径如下：
