【发布时间】：2017-11-24 21:23:17
【问题描述】：
您好，我正在开发一个项目，在该项目中我使用 Ajax 在同一页面上显示输出。它包含一个 JSP 表单，它接受用户输入并将输入存储到数据库中，作为响应，我想显示一条成功消息。
但我没有在同一页面上收到消息。
JSP 代码：- 我尝试过同时使用 get 和 post 方法，但没有用。 单击“添加”按钮时，如果在同一页面上成功插入记录，则应显示成功消息，但我在另一页面上收到该消息。
请帮助解决这个问题。这是我第一次使用 Ajax。我们需要对 web.XML 文件进行任何更改吗？
`
<!DOCTYPE html>
<html>
<head>
<title>Courses</title>
<script>
var request;
function addDetails(){
request=new XMLHttpRequest();
request.onreadystatechange()=getResult();
var cid=document.getElementById("cid").value;
var name=document.getElementById("name").value;
var syllabus=document.getElementById("syllabus").value;
var duration=document.getElementById("duration").value;
var fees=document.getElementById("fees").value;
request.open("get","Courses?cid="+cid,"name="+name,"syllabus="+syllabus,"duration="+duration,"fees="+fees,true);
//request.setRequestHeader("Content-type","application/x-www-form-urlencoded");
//request.send(cid&name&syllabus&duration&fees);
request.send();
}
function getResult(){
if(request.readyState===4&&request.status===200){
var result=request.responseText();
document.getElementbyID("output").innerHTML=result;
}
else{
document.getElementbyID("output").innerHTML="Error";
}
}
</script>
<style>
body {
text-align:center;
}
h1 {
font-size:30px;
font-weight:bold;
color:peru;
}
pre {
font-size:20px;
font-weight:bold;
color:black;
}
</style>
</head>
<body>
<h1>Course Information</h1><br/>
<form action="Courses" method="Post">
<pre>
Course ID : <input type="text" name="cid" id="cid" style="width:400px"/><br/>
Course Name : <input type="text" name="name" id="name" style="width:400px"/><br/>
Syllabus : <input type="text" name="syllabus" id="syllabus" style="width:400px"/><br/>
Duration : <input type="text" name="duration" id="duration" style="width:400px"/><br/>
Fees : <input type="text" name="fees" id="fees" style="width:400px"/><br/>
<input type="submit" name="Add" value="Add" onclick="addDetails()"/> <input type="submit" name="Update" value="Update"/> <input type="submit" name="Delete" value="Delete"/>
<p id="output"></p>
</pre>
</form>
</body>
</html>
` Servlet 代码：-
package ss;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Courses extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try{
String cid=request.getParameter("cid");
String name=request.getParameter("name");
String syllabus=request.getParameter("Syllabus");
String duration=request.getParameter("duration");
String fees=request.getParameter("fees");
Class.forName("com.mysql.jdbc.Driver");
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/ssi","root","root17");
if(request.getParameter("Add")!=null){
String qry="insert into course values(?,?,?,?,?)";
PreparedStatement ps=con.prepareStatement(qry);
ps.setString(1, cid);
ps.setString(2, name);
ps.setString(3, syllabus);
ps.setString(4, duration);
ps.setString(5, fees);
int i=ps.executeUpdate();
if(i>0){
out.println("Registered Successfully");
}
else{
out.println("Registration Fails");
}
}
if(request.getParameter("Update")!=null){
String qry="UPDATE course SET Name=?,Duration=?, syllabus=?, fees=? where cid=?";
PreparedStatement ps=con.prepareStatement(qry);
ps.setString(1,name);
ps.setString(2,duration);
ps.setString(3,syllabus);
ps.setString(4, fees);
ps.setString(5, cid);
int i=ps.executeUpdate();
if(i>0){
out.println("Updated Successfully");
out.println(i);
}
else{
out.println("Update fails");
}
}
if(request.getParameter("Delete")!=null){
String qry="Delete from course where cid=?";
PreparedStatement ps=con.prepareStatement(qry);
ps.setString(1, cid);
int i=ps.executeUpdate();
if(i>0){
out.println("Record Deleted");
}
else{
out.println("Delete Fails");
}
}
}
catch(Exception e){
out.println(e);
}
}
}
【问题讨论】：