Question

servlet新手，什么不是。这就是我的项目布局：

 Projectname 
      src
        servlet.java
      web content
      META-INF
      WEB-INF 
      first.jsp

我的servlet.java的内容：几乎只需要来自jsp的文本字段

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class servlet
 */
@WebServlet("/servlet")
public class servlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public servlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Servlet#destroy()
     */
    public void destroy() {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
     */
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter(); 
        try {

            String user=request.getParameter("string");
            out.println("<h2> Welcome "+user+"</h2>");
        } finally {            
            out.close();
        }
    }

}

jsp：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Input Form</title>
</head>
<body>

<form action="/servlet" method="POST">
  What's your name:<br>
  <input type="text" name="string">
  <br>
  <input type="submit" value="Submit">
</form> 


</body>
</html>

最后是web.xml

<servlet>
    <servlet-name>servlet</servlet-name>
      <jsp-file>/first.jsp</jsp-file>
 </servlet>
 <servlet-mapping>
      <servlet-name>servlet</servlet-name>
      <url-pattern>/servlet</url-pattern>
 </servlet-mapping>

问题是我可以看到基本的jsp，这是提交字符串的形式，但是当我点击提交时没有任何反应。我甚至不知道在哪里寻找错误和日志来找出问题所在。

Answer 1

我们遇到了一些问题，我们在聊天和评论中讨论过：

HttpServlet.service（）被覆盖了一个空实现，因此没有调用doGet（）和doPost（）。
我们在web.xml上有一个jsp，它覆盖了Servlet带注释的映射。

经过审核的代码最终看起来像这样：

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;

/**
 * Servlet implementation class servlet
 */
@WebServlet("/servlet")
public class servlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
     */
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Overriding service() usually isn't needed. - The default implementation mostly
        // does the right thing&reg;
        super.service(request, response) 
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Just forward the request to the jsp page on get requests
        request.getRequestDispatcher("/first.jsp").forward(request,response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter(); 
        try {
            String user=request.getParameter("string");
            out.println("<h2> Welcome "+user+"</h2>");
        } finally {
            // Don't close the Response - it will mess with filters
            // out.close();
            out.flush()
        }
    }
}

Servlet在提交按钮后不起作用

1 个答案: