Android 6.0 无法创建套接字

Question

我无法创建到我的服务器的简单 TCP 连接。我创建了一个 AsyncTask 来发送消息，但它没有用。我在权限中添加了 INTERNET 和 ACCESS_NETWORK_STATE。我不知道还能尝试什么。

public class ServerCommunicator extends AsyncTask<String,Void,Void>{
public static String SERVER_IP = "192.168.2.148";
public static int SERVER_PORT = 1337;
public static String SERVER_PW = "adsfadsf";
public Context context;
@Override
protected Void doInBackground(String... params) {
    //Create Command
    CommandFactory cmdFactory = new CommandFactory();
    Command cmd = cmdFactory.createCommand();
    System.out.println("Cmd created..");

    //-----
    try {
        System.out.println(SERVER_IP);
        InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
        System.out.println("Created serverAddr "+ SERVER_IP);
        Socket socket = new Socket(serverAddr,SERVER_PORT);
        System.out.println("Socket created..");
        //sends the message to the server
        PrintWriter mBufferOut = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
        String msg2Send = Crypter.Encrypt(cmd.toString(), SERVER_PW);
        sendMsgAsByteArr(socket, msg2Send);
        Command recCmd = cmdFactory.extractCommandFromStr(receiveMsg(socket));
        socket.close();
        Toast.makeText(context, recCmd.id, Toast.LENGTH_LONG).show();


    } catch (UnknownHostException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}
private static void sendMsgAsByteArr(Socket socket, String msg) {
    try {
        socket.getOutputStream().write(msg.getBytes());
        System.out.println("sent cmd..");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private static String receiveMsg(Socket socket) {
    String msg = "";
    int c;
    ArrayList<Byte> incoming = new ArrayList<Byte>();
    try {
        while((c = socket.getInputStream().read())!=-1) {
            incoming.add((byte)c);
        }
        byte[] allBytes = new byte[incoming.size()];
        for(int i = 0; i < incoming.size(); i++) {
            allBytes[i] = incoming.get(i);
        }
        msg = new String(allBytes);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return msg;
}
}

我的程序一直运行到 Socket socket = new Socket(serverAddr, SERVER_PORT); 然后停止。它不显示任何堆栈跟踪或错误。

有什么想法吗？

Answer 1

我调试了你的代码，虽然有多个问题，但没有一个与 Android 6 相关。

我为您的代码创建了一个简化版本并让它运行起来。一个问题是您的 context 引用为空，所以我在构造函数中设置了它。另一个问题是您试图在后台线程上显示 Toast，但这是行不通的。另一个问题是您的发送和接收方法，它们对我不起作用。

这是我使用 TCP/IP 服务器获得的简化代码，在 Android 4.4.4 和 Android 6 上进行了测试。您可以根据需要对此进行扩展:

public class ServerCommunicator extends AsyncTask<String,Void,String> {
    public static String SERVER_IP = "11.222.33.444";
    public static int SERVER_PORT = 1234;
    public Context context;

    public ServerCommunicator(Context c) {
        this.context = c;
    }
    @Override
    protected String doInBackground(String... params) {
        try {
            System.out.println(SERVER_IP);
            InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
            System.out.println("Created serverAddr "+ SERVER_IP);
            Socket socket = new Socket(serverAddr,SERVER_PORT);
            System.out.println("Socket created..");
            //sends the message to the server
            PrintWriter mBufferOut = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
            String msg2Send = "{\"HelloWorld\", \"1234\"}";
            mBufferOut.println(msg2Send);

            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String result = in.readLine();
            System.out.println("result: " + result);
            socket.close();


            return result;

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        if (result != null) {
            Toast.makeText(context, result, Toast.LENGTH_LONG).show();
        }
    }
}