request.getParameter 在 servlet dopost 方法中返回 null。我已经检查了 http 请求其发送的正确值。我已经在 chrome 网络选项卡中验证了这一点，但在 servlet 中验证了 request.getParameter("UserQuery"); 的值即将为空，不是问题是什么，尝试了谷歌的一些解决方案，但似乎没有任何效果
Jsp代码：
<!DOCTYPE html>
<html>
<head>
<title>Chatbot</title>
<style>
/* Add responsive CSS styling for the chat interface */
body {
font-family: Arial, sans-serif;
padding: 10px;
}
#chat-container {
border: 1px solid #ccc;
padding: 10px;
width: 50%;
margin: auto;
height: 400px;
overflow-y: scroll;
}
#chat-input {
width: 100%;
padding: 5px;
box-sizing: border-box;
}
#chat-submit {
padding: 5px;
cursor: pointer;
}
.chat-message {
margin: 5px 0;
}
.user-message {
text-align: right;
}
.bot-message {
text-align: left;
}
</style>
</head>
<body>
<h2>Chatbot</h2>
<div id="chat-container">
<!-- Chat history will be displayed here -->
<div id="chat-history"></div>
</div>
<form id="chat-form" method="post" >
<input type="text" id="chat-input" name="userQuery" required placeholder="Type your message here..." />
<input type="button" id="chat-submit" value="Send" onclick="return submitChatForm(event);" />
</form>
<script>
// JavaScript to handle form submission and display chat history
function submitChatForm(event) {
event.preventDefault();
var userQuery = document.getElementById("chat-input").value;
// Create a chat message element for the user's message
var chatHistory = document.getElementById("chat-history");
var userMessageElement = document.createElement("div");
userMessageElement.className = "chat-message user-message";
userMessageElement.innerText = "You: " + userQuery;
chatHistory.appendChild(userMessageElement);
// Send the form data using AJAX
var formData = new FormData();
formData.append("UserQuery", userQuery);
fetch("chatbotServlet", {
method: "POST",
body: formData
})
.then(response => response.text())
.then(data => {
// Create a chat message element for the bot's response
var botMessageElement = document.createElement("div");
botMessageElement.className = "chat-message bot-message";
botMessageElement.innerText = "Bot: " + data;
chatHistory.appendChild(botMessageElement);
// Clear the chat input field
document.getElementById("chat-input").value = "";
// Scroll to the bottom of the chat history
chatHistory.scrollTop = chatHistory.scrollHeight;
})
.catch(error => {
console.error("Error:", error);
});
return false; // Prevent form from submitting the traditional way
}
</script>
</body>
</html>
Servlet -
package com.java.chatbot;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
// Servlet implementation class ChatbotServlet
public class ChatbotServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ChatbotServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
log("get method called");
response.getWriter().append("Served at: ").append(request.getContextPath());
}
/**
* @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/plain;charset=UTF-8");
String userQuery1 = request.getParameter("UserQuery");
log("userQuery" + userQuery1);
String botResponse = getBotResponse(userQuery1);
PrintWriter out = response.getWriter();
out.print(botResponse);
out.flush();
}
private String getBotResponse(String userQuery) {
String botResponse = "";
// Database connection setup
try {
// Replace with your database connection details
Class.forName("com.mysql.cj.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/chatbot_responses", "root", "");
// Query to get random response based on user's query
String query = "SELECT answer FROM chatbot_responses WHERE question = ? ORDER BY RAND() LIMIT 1";
PreparedStatement stmt = conn.prepareStatement(query);
stmt.setString(1, userQuery);
ResultSet rs = stmt.executeQuery();
if (rs.next()) {
botResponse = rs.getString("answer");
}
log("BOTRES" + botResponse);
// Close resources
rs.close();
stmt.close();
conn.close();
}
catch (Exception e) {
e.printStackTrace();
botResponse = "Sorry, there was an error processing your request.";
}
return botResponse;
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="https://jakarta.ee/xml/ns/jakartaee" xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd" version="5.0">
<servlet>
<description></description>
<display-name>ChatbotServlet</display-name>
<servlet-name>ChatbotServlet</servlet-name>
<servlet-class>com.java.chatbot.ChatbotServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ChatbotServlet</servlet-name>
<url-pattern>/chatbotServlet</url-pattern>
</servlet-mapping>
<display-name>chatbot</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
</web-app>
在尝试 stackoverflow 之前我已经用 google 搜索过了，但没有任何效果
由于您将
FormDatafetchmultipart:form-datanull您需要将内容类型标头更改为
x-www-form-urlencodedUrlSearchParamfetch("chatbotServlet", {
method: "POST",
body: new URLSearchParams(formData)
})