这是我的情况（在真实设备上，而不是模拟器上）：
我有一个App_A，它通过 TCP 将一些数据流式传输到另一个可能是同一设备上的App_B的软件。
在App_A用户手册中，据说可以将数据流式传输到同一设备上的另一个应用程序（本例中为App_B ），只需通过App_A中提供的选项将destination_IP 更改为“localhost”并将destination_port 更改为“8888” 。
因此，数据流是从源到App_a最后到App_B。
在这种情况下，我将 App_B 开发为一个 TCP 客户端应用程序，用于侦听设备上的任何流式 TCP 数据。
这是我写的代码（在网上找到）：
主要活动
public class MainActivity extends AppCompatActivity {
TcpClient mTcpClient;
Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = this;
new ConnectTask().execute("");
}
public class ConnectTask extends AsyncTask<String, String, TcpClient> {
@Override
protected TcpClient doInBackground(String... message) {
//we create a TCPClient object
mTcpClient = new TcpClient(new TcpClient.OnMessageReceived() {
@Override
//here the messageReceived method is implemented
public void messageReceived(String message) {
//this method calls the onProgressUpdate
publishProgress(message);
}
});
mTcpClient.run();
return null;
}
@Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
//response received from server
Toast.makeText(context, "Ricevo "+values[0], Toast.LENGTH_LONG).show();
Log.e("test", "response " + values[0]);
//process server response here....
}
}
}
TCP_CLIENT
public class TcpClient {
public static final String SERVER_IP = "localhost";
public static final int SERVER_PORT = 8888;
private String mServerMessage;
private OnMessageReceived mMessageListener = null;
private boolean mRun = false;
private PrintWriter mBufferOut;
private BufferedReader mBufferIn;
public TcpClient(OnMessageReceived listener) {
mMessageListener = listener;
}
public void sendMessage(String message) {
if (mBufferOut != null && !mBufferOut.checkError()) {
mBufferOut.println(message);
mBufferOut.flush();
}
}
public void stopClient() {
mRun = false;
if (mBufferOut != null) {
mBufferOut.flush();
mBufferOut.close();
}
mMessageListener = null;
mBufferIn = null;
mBufferOut = null;
mServerMessage = null;
}
public void run() {
mRun = true;
try {
InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
Log.e("TCP Client", "C: Connecting...");
try (Socket socket = new Socket(serverAddr, SERVER_PORT)) {
//sends the message to the server
mBufferOut = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
//receives the message which the server sends back
mBufferIn = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//in this while the client listens for the messages sent by the server
while (mRun) {
mServerMessage = mBufferIn.readLine();
if (mServerMessage != null && mMessageListener != null) {
//call the method messageReceived from MyActivity class
mMessageListener.messageReceived(mServerMessage);
}
}
Log.e("RESPONSE FROM SERVER", "S: Received Message: '" + mServerMessage + "'");
} catch (Exception e) {
Log.e("TCP", "S: Error", e);
}
//the socket must be closed. It is not possible to reconnect to this socket
// after it is closed, which means a new socket instance has to be created.
} catch (Exception e) {
Log.e("TCP", "C: Error", e);
}
}
public interface OnMessageReceived {
public void messageReceived(String message);
}
}
我的问题是，我在 Socket 构造函数中作为第一个参数放置的每个值（在 TcpClient 类 > 运行方法 > 尝试资源语句中），它都会引发以下异常：
java.net.ConnectException: failed to connect to localhost/127.0.0.1 (port 8888): connect failed: ECONNREFUSED (Connection refused)
我试图写下所有的语句，但我无法解决这个问题：
try (Socket socket = new Socket("localhost", SERVER_PORT)) ....
try (Socket socket = new Socket("127.0.0.1", SERVER_PORT)) ....
try (Socket socket = new Socket(InetAddress.getByName(SERVER_IP), SERVER_PORT)) ....
try (Socket socket = new Socket(InetAddress.getLocalHost(), SERVER_PORT)) ....
我读到只有当我需要访问模拟器上的本地主机时，本地主机 IP 必须是“10.0.2.2”，这不是我的情况。无论如何，我也在设备上尝试了这个选项，但它不起作用，并且抛出了带有 ETIMEDOUT（连接超时）的 ConnectException。
我知道我的代码没有针对这种情况进行优化，但目前我只关心 TCP 通信是否正常工作，而不关心性能问题。
我会请求你的帮助，如果你能帮助我，我将不胜感激。