如何在Android中将套接字事件作为后台服务来处理？

Question

我是Android开发的新手,我希望我的应用程序能够检测套接字事件,即使应用程序未通过后台服务处于活动状态(因此我可以执行推送通知,例如,如果有一个新的消息由套接字事件触发,如Whatsapp和其他人这样做).

我实现了后台服务和一个启动服务的应用程序类,但是在后台服务中将套接字事件作为Runnable任务放在哪里以及如何放置.

我修改了下面的socket.io android chat项目示例并添加了服务和应用程序类.

ChatApplication.java

package com.github.nkzawa.socketio.androidchat;

import android.app.Application;
import android.content.Intent;
import android.content.res.Configuration;

import io.socket.client.IO;
import io.socket.client.Socket;

import java.net.URISyntaxException;

public class ChatApplication extends Application {

    @Override
    // called when the application is starting, before any other application objects have been created
    public void onCreate() {
        super.onCreate();

        // represents our background service
        Intent background = new Intent(this, SocketBackgroundService.class);
        startService(background);
    }

    private Socket mSocket;
    {
        try {
            mSocket = IO.socket(Constants.CHAT_SERVER_URL);
        } catch (URISyntaxException e) {
            throw new RuntimeException(e);
        }
    }

    public Socket getSocket() {
        return mSocket;
    }
}

SocketBackgroundService.java

package com.github.nkzawa.socketio.androidchat;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

public class SocketBackgroundService extends Service {
    private boolean isRunning;
    private Thread backgroundThread;

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        this.isRunning = false;
        this.backgroundThread = new Thread(myTask);
    }

    private Runnable myTask = new Runnable() {
        @Override
        public void run() {
            // do something in here
            Log.i("INFO", "SOCKET BACKGROUND SERVICE IS RUNNING");

            //TODO - how to handle socket events here?
            //How do I do something like mSocket.on(Socket.EVENT_CONNECT,onConnect); here?
        }
    };

    @Override
    public void onDestroy() {
        this.isRunning = false;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if( !this.isRunning) {
            this.isRunning = true;
            this.backgroundThread.start();
        }

        return START_STICKY;
    }
}

Answer 1

如果您需要套接字，即使您的应用程序停止后也要保持活动状态。将套接字移至后台服务，然后可以在服务中添加套接字事件。

Answer 2

您在主线程上打开套接字。不要在主线程上打开套接字连接，它会给你 ANR（应用程序无响应）错误，这是由于 UI 线程上的大量工作而发生的。它阻塞 UI 线程超过 5 秒。所以我建议你在服务内部的线程上打开套接字连接。
这是使用普通套接字的示例：

1. 创建一个服务类用于在后台服务上启动线程
2. 在 Thread 类上创建以在线程上打开套接字连接

3. 为套接字通信创建单独的类

   public class SocketBackgroundService extends Service {
   
   private SocketThread mSocketThread;
   
   @Override
   public IBinder onBind(Intent intent) {
       return null;
   }
   
   @Override
   public void onCreate() {
   
       mSocketThread = SocketThread.getInstance();
   }
   
   
   @Override
   public void onDestroy() {
       //stop thread and socket connection here
   }
   
   @Override
   public int onStartCommand(Intent intent, int flags, int startId) {
       if (mSocketThread.startThread) {
       } else {
           stopSelf();
       }
   
       return START_STICKY;
   }
   }
   
   public class SocketThread extends Thread {
   
   private static SocketThread mSocketThread;
   private SocketClient mSocketClient;
   
   private SocketThread() {
   }
   
   // create single instance of socket thread class
   public static SocketThread getInstance() {
       if (mSocketThread == null)//you can use synchronized also
       {
           mSocketThread = new SocketThread();
       }
       return mSocketThread;
   }
   
   
   public boolean startThread() {
         mSocketClient = new SocketClient();
       if (socketClient.isConnected()) {
           mSocketThread.start()
           return true;
       }
       return false;
   }
   
   @Override
   public void run() {
       super.run();
       while (mSocketClient.isConnected()) {
           // continue listen
       }
       // otherwise remove socketClient instance and stop thread
   }
   
   public class SocketClient {
       //write all code here regarding opening, closing sockets
       //create constructor
       public SocketClient() {
           // open socket connection here
       }
   
       public boolean isConnected() {
           return true;
       }
   }