我正在制作和应用程序,使用套接字从Android设备向服务器发送数据,反之亦然。 我正在使用AsyncTask类来处理连接。我的问题是,在我的主Activity类中,我必须从输入流中读取,例如。
conhandler = new ConnectionHandler();
conhandler.execute();
Log.i("AppOne", "Reading from stream");
message = conhandler.readFromStream();
并且会发生这样的代码片段在我的ConnectionHandler类建立套接字连接之前执行。有没有办法解决这个问题? 这是我的ConnectionHandler类的代码:
public class ConnectionHandler extends AsyncTask<Void, Void, Void>{
public static String serverip = "192.168.1.100";
public static int serverport = 7777;
Socket s;
public DataInputStream dis = null;
public DataOutputStream dos = null;
public int message;
@Override
protected Void doInBackground(Void... params) {
try {
Log.i("AsyncTank", "doInBackgoung: Creating Socket");
s = new Socket("192.168.1.100", 7777);
} catch (Exception e) {
Log.i("AsyncTank", "doInBackgoung: Cannot create Socket");
}
Log.i("AsyncTank", "doInBackgoung: Socket created");
if (s.isConnected()) {
try {
Log.i("AsyncTank", "doInBackgoung: inside input try");
dis = new DataInputStream(s.getInputStream());
Log.i("AsyncTank", "doInBackgoung: InputStream assigned");
} catch (IOException e) {
// TODO Auto-generated catch block
Log.i("AsyncTank", "doInBackgoung: Cannot assign Streams, Socket not connected");
e.printStackTrace();
}
try {
Log.i("AsyncTank", "doInBackgoung: inside output try");
dos = new DataOutputStream(s.getOutputStream());
Log.i("AsyncTank", "doInBackgoung: OutputStream assigned");
} catch (IOException e) {
// TODO Auto-generated catch block
Log.i("AsyncTank", "doInBackgoung: Cannot assign Streams, Socket not connected");
e.printStackTrace();
}
} else {
Log.i("AsyncTank", "doInBackgoung: Cannot assign Streams, Socket is closed");
}
return null;
}
public void writeToStream(double lat, double lon) {
try {
Log.i("AsynkTask", "writeToStream : Writing lat");
dos.writeDouble(lat);
dos.flush();
} catch (Exception e) {
Log.i("AsynkTask", "writeToStream : Writing failed");
}
try {
Log.i("AsynkTask", "writeToStream : Writing lon");
dos.writeDouble(lon);
dos.flush();
} catch (Exception e) {
Log.i("AsynkTask", "writeToStream : Writing failed");
}
}
public int readFromStream() {
try {
if (s.isConnected()) {
Log.i("AsynkTask", "readFromStream : Reading message");
message = dis.readInt();
} else {
Log.i("AsynkTask", "readFromStream : Cannot Read, Socket is closed");
}
} catch (Exception e) {
Log.i("AsynkTask", "readFromStream : Reading failed");
}
return message;
}
}
答案 0 :(得分:2)
是的,你需要在ASyncTask
线程中进行所有网络操作。通过覆盖onPostExecute()
方法,您还可以在任务完成时执行操作。其中的东西在UI线程上运行,因此您可以操作文本视图,布局等。
如何使用asynctask打开套接字并为其写入双精度的示例:
public class ASyncExample extends Activity {
private TextView mTextView;
@Override
protected void onCreate(Bundle savedInstanceState) {
// set stuff up
super.onCreate(savedInstanceState);
}
private class WriteToServer extends AsyncTask<Double, Void, Void> {
private final String serverip = "192.168.1.100";
private final int serverport = 7777;
Socket s;
private DataOutputStream dos = null;
@Override
protected Void doInBackground(Double... params) {
try {
// open the stream
s = new Socket("192.168.1.100", 7777);
dos = new DataOutputStream(s.getOutputStream());
// write the passed double to the stream
dos.writeDouble(params[0]);
dos.flush();
} catch (Exception e) {
Log.i("AsyncTank", "something's gone wrong");
}
return null;
}
}
}