我想将图像从 java websocket 服务器发送到 HTML5 页面。当我尝试发送字符串客户端收到正确的信息时，但是当我想在 byteArray 中发送图像时出现错误：
"WebSocket connection to 'ws://127.0.0.1:9000/' failed: Unrecognized frame opcode: 15"
我的服务器代码：
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.security.MessageDigest;
import javax.imageio.ImageIO;
import javax.xml.bind.DatatypeConverter;
public class WebSocket {
private ServerSocket server;
private Socket sock;
private InputStream in;
private OutputStream out;
public WebSocket() {
}
public void listen(int port) throws IOException {
server = new ServerSocket(port);
sock = server.accept();
server.close();
in = sock.getInputStream();
out = sock.getOutputStream();
}
private void handshake() throws Exception {
BufferedReader br = new BufferedReader(
new InputStreamReader(in, "UTF8"));
PrintWriter pw = new PrintWriter(new OutputStreamWriter(out, "UTF8"));
// the first line of HTTP headers
String line = br.readLine();
if (!line.startsWith("GET"))
throw new IOException("Wrong header: " + line);
// we read header fields
String key = null;
// read line by line until we get empty line
while (!(line = br.readLine()).isEmpty()) {
if (line.toLowerCase().contains("sec-websocket-key")) {
key = line.substring(line.indexOf(":") + 1).trim();
}
}
if (key == null)
throw new IOException("No Websocket key specified");
System.out.println(key);
// add key and magic value
String accept = key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
// sha1
byte[] digest = MessageDigest.getInstance("SHA-1").digest(
accept.getBytes("UTF8"));
// and base64
accept = DatatypeConverter.printBase64Binary(digest);
// send http headers
pw.println("HTTP/1.1 101 Switching Protocols");
pw.println("Upgrade: websocket");
pw.println("Connection: Upgrade");
pw.println("Sec-WebSocket-Accept: " + accept);
pw.println();
pw.flush();
}
private void send(String message) throws Exception {
BufferedImage image = ImageIO.read(new File("image.jpg"));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(image, "jpg", baos);
byte[] byteArray = baos.toByteArray();
out.write(byteArray);
out.flush();
}
private void close() {
try {
sock.close();
} catch (IOException e) {
System.err.println(e);
}
}
/** throws Exception, because we don't really care much in this example */
public static void main(String[] args) throws Exception {
WebSocket ws = new WebSocket();
System.out.println("Listening...");
ws.listen(9000);
System.out.println("Handshake");
ws.handshake();
System.out.println("Handshake complete!");
ws.send("I got your message! It's length was");
ws.close();
}
}
和我的 html 页面：
<!DOCTYPE HTML>
<html>
<body>
<button onclick="webs()">WebSocket message</button>
<script>
function webs() {
var ws = new WebSocket("ws://127.0.0.1:9000");
ws.onopen = function(){
console.log("Opened!");
};
ws.onmessage = function(evt){
console.log("Received!");
};
ws.onclose = function(ev){
console.log("Closing connection");
};
ws.onerror = function(ev){
console.log("Connection error: " + ev.reason);
};
}
</script>
</body>
</html>
我怀疑这个握手和 http 标头有问题，但我不知道是什么。