我正在实现一个 WebSocket 服务器(出于学习目的)，并且我让它正确处理握手(websocket.onopen 被调用，所以我认为这意味着握手成功)，但是，当客户端(浏览器)在握手后发送一条消息，服务器永远不会收到它。
使用 Chrome 的开发人员工具，我可以看到所有 header 均已正确接收，并且没有引发任何错误。它还说它发送了“hello”，尽管 readLine() 在 Java 中从未触发。
我的代码有什么问题？
编辑1:我发现，如果我刷新网页，那么(并且只有那时)ServerSocket 才会从最后一个连接(刷新刚刚终止)接收数据!为什么这是它接收它的唯一方式？
编辑2:我还发现我可以在握手后向客户端发送消息并且客户端收到它，但服务器仍然从未收到客户端的消息!我像这样向客户端发送了消息:
byte[] message = new byte[ 7 ];
message[ 0 ] = new Integer(129).byteValue();
message[ 1 ] = new Integer(5).byteValue();
byte[] raw = "hello".getBytes();
message[ 2 ] = raw[ 0 ];
message[ 3 ] = raw[ 1 ];
message[ 4 ] = raw[ 2 ];
message[ 5 ] = raw[ 3 ];
message[ 6 ] = raw[ 4 ];
outStream.write( message);
out.println();
HTML 页面
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>WebSocket Test</title></head>
<body>
<script>
try
{
function writeToScreen(message)
{
var p = document.createElement( "p" );
p.innerHTML = message;
document.getElementsByTagName( "body" )[ 0 ].appendChild( p );
}
function onOpen(evt)
{
writeToScreen( "opened" );
doSend( "hello" );
//We reach here but the server never recieves the message! (and bufferedAmount == 0)
writeToScreen( "sent: " + websocket.bufferedAmount );
}
function onClose(evt)
{
alert( "closed" );
websocket.close();
}
function onMessage(evt)
{
alert( "Message: " + evt.data );
}
function onError(evt)
{
alert( "Error: " + evt );
}
function doSend (message)
{
websocket.send( message );
}
//PUT IN YOUR OWN LOCAL IP ADDRESS HERE TO GET IT TO WORK
var websocket = new WebSocket( "ws://192.168.1.19:4444/" );
websocket.onopen = onOpen;
websocket.onclose = onClose;
websocket.onmessage = onMessage;
websocket.onerror = onError;
}
catch(e)
{
}
</script>
</body>
</html>
JAVA代码
import java.net.*;
import java.io.*;
import java.security.*;
public class WebListener
{
public static void main(String[] args) throws Exception
{
ServerSocket serverSocket = null;
boolean listening = true;
try {
serverSocket = new ServerSocket(4444);
} catch (IOException e) {
System.err.println("Could not listen on port: 4444.");
System.exit(-1);
}
while (listening) new ServerThread(serverSocket.accept()).start();
serverSocket.close();
}
}
class ServerThread extends Thread {
private Socket socket = null;
public ServerThread(Socket socket) {
super("ServerThread");
this.socket = socket;
}
public void run() {
try {
OutputStream outStream = null;
PrintWriter out = new PrintWriter( outStream = socket.getOutputStream(), true);
BufferedReader in = new BufferedReader( new InputStreamReader( socket.getInputStream()));
String inputLine, outputLine;
//Handle the headers first
doHeaders( out, in );
//Now read anything they have to send
while ( ( inputLine = in.readLine() ) != null )
{
//WE NEVER REACH HERE!
System.out.println( inputLine );
}
out.close();
in.close();
socket.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public void doHeaders(PrintWriter out, BufferedReader in) throws Exception
{
String inputLine = null;
String key = null;
//Read the headers
while ( ( inputLine = in.readLine() ) != null )
{
//Get the key
if ( inputLine.startsWith( "Sec-WebSocket-Key" ) ) key = inputLine.substring( "Sec-WebSocket-Key: ".length() );
//They're done
if ( inputLine.equals( "" ) ) break;
}
//We need a key to continue
if ( key == null ) throw new Exception( "No Sec-WebSocket-Key was passed!" );
//Send our headers
out.println( "HTTP/1.1 101 Web Socket Protocol Handshake\r" );
out.println( "Upgrade: websocket\r" );
out.println( "Connection: Upgrade\r" );
out.println( "Sec-WebSocket-Accept: " + createOK( key ) + "\r" );
out.println( "\r" );
}
public String createOK(String key) throws NoSuchAlgorithmException, UnsupportedEncodingException, Exception
{
String uid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
String text = key + uid;
MessageDigest md = MessageDigest.getInstance( "SHA-1" );
byte[] sha1hash = new byte[40];
md.update( text.getBytes("iso-8859-1"), 0, text.length());
sha1hash = md.digest();
return new String( base64( sha1hash ) );
}
public byte[] base64(byte[] bytes) throws Exception
{
ByteArrayOutputStream out_bytes = new ByteArrayOutputStream();
OutputStream out = new Base64.OutputStream(out_bytes); //Using http://iharder.net/base64
out.write(bytes);
out.close();
return out_bytes.toByteArray();
}
private String convertToHex(byte[] data) {
StringBuffer buf = new StringBuffer();
for (int i = 0; i < data.length; i++) {
int halfbyte = (data[i] >>> 4) & 0x0F;
int two_halfs = 0;
do {
if ((0 <= halfbyte) && (halfbyte <= 9))
buf.append((char) ('0' + halfbyte));
else
buf.append((char) ('a' + (halfbyte - 10)));
halfbyte = data[i] & 0x0F;
} while(two_halfs++ < 1);
}
return buf.toString();
}
}
最佳答案
WebSocket 消息不会由 \r\n 终止，因此您无法使用 in.readline() 读取它们。请参阅data framing规范中有关如何构造消息的部分。
对于从客户端(浏览器)到服务器的文本消息，消息将采用以下形式:
- (字节)0x81
- 1、3或9字节结构，指示消息长度以及消息正文是否被屏蔽。 (来自浏览器的消息应始终被屏蔽。)
- 4 字节掩码
- 消息(utf-8 编码)
没有可以搜索的消息结束标记。您只需读取客户端请求的前几个字节即可计算出其有效负载的长度。
关于java - 为什么我的服务器从来没有收到 WebSocket 发送的信息？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12102513/