Question

当我调用方法request.getParameter（＆＃34; username＆＃34;）时，我得到null，为什么我没有得到正确的json字符串格式？我也尝试使用JSON.stringify（），但结果是一样的。我希望有人知道出了什么问题。

LoginServlet.java

 package org.SalonNamestaja.Controller.Ajax;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

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

import org.SalonNamestaja.Services.LoginService;
import org.apache.catalina.User;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Servlet implementation class LoginServlet
 */
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    List<User> users = new LinkedList<User>();

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

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        String jsonUsername = request.getParameter("username");
        String jsonPassword = request.getParameter("pass");
        PrintWriter out = response.getWriter();
        out.print("Hello " + jsonUsername + " " + jsonPassword );
    }

}

login_user.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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=UTF-8">
<title>Prijava korisnika</title>
<script src="javascript/jquery-1.11.3.min.js"></script>
<script src="http://code.jquery.com/jquery-migrate-1.2.1.min.js"></script>
<script >
$(document).ready(function(){

    var $name = $('#userName');
    var $pass = $('#password');

    $('#form').submit(function() {

    $.post("/SalonNamestaja/login", {username:$('#userName').val(), pass:$('#password').val()},function(data){
        alert(data);
    });

    });
});
</script>
</head>
<body>

<form id="form" action="/SalonNamestaja/login" method="post">
    Korisnicko ime:<input id="userName" type="text" name="userName"><br>
    Sifra:<input id="password" type="password" name="password"><br>
    <input type="submit" value="Prijavi se">
</form>

<div id="welcometext">
</div>

</body>
</html>

Answer 1

我认为你认为javascript正在以php运行。当文档准备就绪时 - 当您打开浏览器时，您将获取变量并发送$ .post。我假设您想在表单提交上执行此操作。将脚本修改为：

<script>
function sendForm() {
// PUT YOUR CODE HERE
}
</script>

并修改您的表单，您的提交按钮标记应如下所示：

<input type="submit" value="Prijavi se" onclick="sendForm()">

我不确定这是否会解决您的问题，您可以通过迭代request.getParameterNames检查是否发送了任何参数

JSP ajax json post返回null作为数据

1 个答案: