我正在开发一个简单的服务器，只是为了了解它是如何工作的。我有一个 java 服务器和 java 客户端可以工作，但是试图让 javascript 客户端连接到同一个 java 服务器让我发疯!
Java 服务器:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class DateServer {
public static void main(String[] args) throws IOException {
ServerSocket listener = new ServerSocket(9091);
System.out.println("Starting");
try {
while (true) {
System.out.println("While");
Socket socket = listener.accept();
System.out.println("Accepted");
BufferedReader input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String msg = input.readLine();
System.out.println("Message from client: " + msg);
try {
PrintWriter out =
new PrintWriter(socket.getOutputStream(), true);
System.out.println("Sending message...");
out.println("Hi");
} finally {
System.out.println("Closing socket");
socket.close();
}
}
}
finally {
listener.close();
}
}
}
Java 客户端:(有效)
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import javax.swing.JOptionPane;
public class DateClient {
public static void main(String[] args) throws IOException {
Socket s = new Socket("localhost", 9091);
try {
PrintWriter out =
new PrintWriter(s.getOutputStream(), true);
System.out.println("Sending message...");
out.println("I'm the client");
} finally {
//System.out.println("Closing socket");
//s.close();
}
BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream()));
String msg = input.readLine();
System.out.println(msg);
JOptionPane.showMessageDialog(null, msg);
s.close();
System.exit(0);
}
}
JavaScript 客户端:
<!DOCTYPE html>
<html>
<head>
<title>Echo Test</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width">
</head>
<body>
<div id="messages"></div>
<script type="text/javascript">
var connection = new WebSocket('ws://localhost:9091/');
var messages = document.getElementById("messages");
// When the connection is open, send some data to the server
connection.onopen = function (e) {
writeResponse('sent');
connection.send('Ping');
}
// Log errors
connection.onerror = function (error) {
writeResponse('Error: ' + error);
}
connection.onclose = function(e){
writeResponse("Disconnected: " + e.data);
}
// Log messages from the server
connection.onmessage = function (e) {
writeResponse('Server: ' + e.data);
}
function writeResponse(text){
messages.innerHTML += "<br/>" + text;
}
</script>
</body>
</html>
当我在服务器上运行 java 客户端时，我得到:
Starting
While
Accepted
Message from client: I'm the client
Sending message...
Closing socket
While
以及客户端的输出:
Sending message...
Hi
这样就可以了。当我运行 javascript 客户端时，服务器的输出是:
Starting
While
Accepted
Message from client: GET / HTTP/1.1
Sending message...
Closing socket
While
JavaScript 页面上的输出是:
Error: [object Event]
Disconnected: undefined
此外，Firefox 控制台显示“Firefox 无法与 ws://localhost:9091/处的服务器建立连接”。我缺少什么？谢谢!
最佳答案
来自浏览器的 webSocket 连接不仅仅是普通的 TCP 连接。它必须支持完整的 webSocket 协议(protocol)，否则浏览器将无法连接到它或交换数据。这个完整的 webSocket 协议(protocol)包括:
- 通过 HTTP 进行初始连接
- webSocket 协议(protocol)的升级
- 初始化 webSocket 连接的安全过程
- webSocket数据包格式
您可以在这里阅读更多相关信息:https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers
关于Javascript客户端无法连接到java服务器，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36124630/