我试图使用套接字。连接到由Geoloqi托管的流媒体服务器
我抓住了Gottox插座。io-java-client代码直接从github,没有做任何修改,除了改变url,但它给了我"错误而握手"的消息。url应该可以工作,因为我从Geoloqi的制造者那里得到了它:https://community.geoloqi.com/discussion/19/data-streaming#Item_11(参见第一个响应)。
下面是代码,来自BasicExample.java
package basic;
/*
* socket.io-java-client Test.java
*
* Copyright (c) 2012, Enno Boland
* socket.io-java-client is a implementation of the socket.io protocol in Java.
*
* See LICENSE file for more information
*/
import io.socket.IOAcknowledge;
import io.socket.IOCallback;
import io.socket.SocketIO;
import io.socket.SocketIOException;
import org.json.JSONException;
import org.json.JSONObject;
public class BasicExample implements IOCallback {
private SocketIO socket;
/**
* @param args
*/
public static void main(String[] args) {
try {
new BasicExample();
} catch (Exception e) {
e.printStackTrace();
}
}
public BasicExample() throws Exception {
socket = new SocketIO();
// socket.connect("http://localhost:8080/", this);
socket.connect("https://subscribe.geoloqi.com:443", this);
// Sends a string to the server.
socket.send("Hello Server");
// Sends a JSON object to the server.
socket.send(new JSONObject().put("key", "value").put("key2",
"another value"));
// Emits an event to the server.
socket.emit("event", "argument1", "argument2", 13.37);
}
@Override
public void onMessage(JSONObject json, IOAcknowledge ack) {
try {
System.out.println("Server said:" + json.toString(2));
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onMessage(String data, IOAcknowledge ack) {
System.out.println("Server said: " + data);
}
@Override
public void onError(SocketIOException socketIOException) {
System.out.println("an Error occured");
socketIOException.printStackTrace();
}
@Override
public void onDisconnect() {
System.out.println("Connection terminated.");
}
@Override
public void onConnect() {
System.out.println("Connection established");
}
@Override
public void on(String event, IOAcknowledge ack, Object... args) {
System.out.println("Server triggered event '" + event + "'");
}
}
错误信息如下:
an Error occured
io.socket.SocketIOException: Error while handshaking
at io.socket.IOConnection.handshake(IOConnection.java:322)
at io.socket.IOConnection.access$7(IOConnection.java:292)
at io.socket.IOConnection$ConnectThread.run(IOConnection.java:199)
Caused by: java.lang.NullPointerException
at io.socket.IOConnection.handshake(IOConnection.java:302)
... 2 more
May 1, 2013 10:02:49 PM io.socket.IOConnection cleanup
INFO: Cleanup
代码出了什么问题?
查看异常来自的源代码(IOConnection.java:302
,来自内部NullPointerException
),有这段代码:
if (connection instanceof HttpsURLConnection) {
((HttpsURLConnection) connection)
.setSSLSocketFactory(sslContext.getSocketFactory());
}
显然connection
必须非空,否则不能通过instanceof
检验。因此,sslContext
必须为空。由于该文件中sslContext
被引用的唯一其他位置是setSslContext()
和getSslContext()
,因此唯一合乎逻辑的结论是,在进行SSL连接之前,必须先调用setSslContext()
。SocketIO.setDefaultSSLSocketFactory()
也调用到IOConnection.setSslContext()
,所以你也可以调用它。
试试这个:
SocketIO.setDefaultSSLSocketFactory(SSLContext.getDefault());
socket = new SocketIO();
socket.connect("https://subscribe.geoloqi.com:443", this);
...
当我使用https://github.com/Gottox/socket.io-java-client创建Java客户机时,我得到了相同的错误。好像我的服务器是基于1的。它只支持1.0 (https://github.com/Gottox/socket.io-java-client/issues/101)。通过使用https://github.com/socketio/socket.io-client-java解决