即使活动发生变化，如何保持 android 客户端连接到服务器并将数据发送到服务器? [英] How to keep the android client connected to the server even on activity changes and send data to server?
问题描述
我最初在我的活动中实现了一个异步任务，它将数据发送到服务器.但是当我改变活动时，连接丢失了.为了避免这种情况，我的方法是实现一个集中网络操作并将数据发送到服务器的服务，该服务的代码如下
I initially implemented an async task in my activity which sends data to the server. But when i changed activities the connection was lost. To avoid this my approach was to implement a service that centralizes the network operation and sends data to the server and the code for this service is given below
import java.io.BufferedWriter;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;
public class SocketService extends Service {
public static final String SERVERIP = ""; //your computer IP address should be written here
public static final int SERVERPORT = 5000;
PrintWriter out;
Socket socket;
InetAddress serverAddr;
@Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
System.out.println("I am in Ibinder onBind method");
return myBinder;
}
private final IBinder myBinder = new LocalBinder();
TCPClient mTcpClient = new TCPClient();
public class LocalBinder extends Binder {
public SocketService getService() {
System.out.println("I am in Localbinder ");
return SocketService.this;
}
}
@Override
public void onCreate() {
super.onCreate();
System.out.println("I am in on create");
}
public void IsBoundable(){
Toast.makeText(this,"I bind like butter", Toast.LENGTH_LONG).show();
}
public void sendMessage(String message){
if (out != null && !out.checkError()) {
System.out.println("in sendMessage"+message);
out.println(message);
out.flush();
}
}
@Override
public int onStartCommand(Intent intent,int flags, int startId){
super.onStartCommand(intent, flags, startId);
System.out.println("I am in on start");
// Toast.makeText(this,"Service created ...", Toast.LENGTH_LONG).show();
Runnable connect = new connectSocket();
new Thread(connect).start();
return START_STICKY;
}
class connectSocket implements Runnable {
@Override
public void run() {
try {
//here you must put your computer's IP address.
serverAddr = InetAddress.getByName(SERVERIP);
Log.e("TCP Client", "C: Connecting...");
//create a socket to make the connection with the server
socket = new Socket(serverAddr, SERVERPORT);
try {
//send the message to the server
out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
Log.e("TCP Client", "C: Sent.");
Log.e("TCP Client", "C: Done.");
}
catch (Exception e) {
Log.e("TCP", "S: Error", e);
}
} catch (Exception e) {
Log.e("TCP", "C: Error", e);
}
}
}
@Override
public void onDestroy() {
super.onDestroy();
try {
socket.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
socket = null;
}
}
Rotator.java 是我绑定到此服务的活动.以下是我的活动中的几段代码.
Rotator.java is my activity which I bind to this service. Following are few pieces of code from my activity.
private ServiceConnection mConnection = new ServiceConnection() {
//EDITED PART
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
// TODO Auto-generated method stub
mBoundService = ((SocketService.LocalBinder)service).getService();
}
@Override
public void onServiceDisconnected(ComponentName name) {
// TODO Auto-generated method stub
mBoundService = null;
}
};
private void doBindService() {
bindService(new Intent(Rotator.this, SocketService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
if(mBoundService!=null){
mBoundService.IsBoundable();
}
}
private void doUnbindService() {
if (mIsBound) {
// Detach our existing connection.
unbindService(mConnection);
mIsBound = false;
}
}
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
gestureDetector = new GestureDetector(this, new GestureListener());
setContentView(R.layout.activity_rotator);
//Binding the activity to the service to perform client-server operations
//start service on create
startService(new Intent(Rotator.this,SocketService.class));
doBindService();
...........
...........
}
@Override
protected void onDestroy() {
super.onDestroy();
doUnbindService();
}
现在这个服务在后台运行，如果我想向服务器发送一些数据，我使用以下内容
Now as this service runs in the background, If i want to send some data to the server i use the following
if(mBoundService!=null)
{
mBoundService.sendMessage("right");
}
推荐答案
代码是对的.唯一的错误是我试图在 onServiceConnected() 方法中启动服务两次，另一次在 onCreate() 方法中.
The code is right. The only mistake was that I was trying to start the service twice once in onServiceConnected() method and the other in onCreate() method.
我更改了代码以仅在启动器活动的 onCreate() 方法中启动服务.其余的 Activity 直接使用 doBindService() 方法绑定到服务
I changed my code to start the service only in onCreate() method in the launcher activity. The rest of the activities directly bind to the service by using doBindService() method
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