Android中使用WebSocket-2

上一篇提到在Android中使用WebSocket和服务端进行通信。是直接在Activity里面进行操作的这样会保持一个长连接，一个应用里面没必要也不应该保持多个长连接，所以我们可以把WebSocket客户端挪到Service里面，使用广播和Activity进行通信。

1. APP端：
   继承BroadcastReceiver，重写public void onReceive(Context context, Intent intent)方法，在该方法中进行业务处理。

   public class MainActivity extends AppCompatActivity implements View.OnClickListener {
   
       private TextView showMessage;
       private EditText editText;
       private StringBuilder sb = new StringBuilder();
       private WebSocketBroadcastReceiver webSocketBroadcastReceiver;
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           Intent intent = new Intent(this, WebSocketService.class);
           startService(intent);
           showMessage = findViewById(R.id.show_message);
           editText = findViewById(R.id.edit_text);
           findViewById(R.id.send).setOnClickListener(this);
           webSocketBroadcastReceiver = new WebSocketBroadcastReceiver();
           IntentFilter intentFilter = new IntentFilter("web_socket");
           registerReceiver(webSocketBroadcastReceiver, intentFilter);
       }
   
       @Override
       public void onClick(View v) {
           switch (v.getId()) {
               case R.id.send:
   
                   sb.append("客户端发送消息：");
                   sb.append(new Date().toLocaleString());
                   sb.append("\n");
                   sb.append(editText.getText().toString().trim());
                   sb.append("\n");
                   showMessage.setText(sb.toString());
                   Intent intent = new Intent(this, WebSocketService.class);
                   intent.putExtra("message", editText.getText().toString().trim());
                   startService(intent);
                   editText.setText("");
                   break;
               default:
                   break;
           }
       }
   
       class WebSocketBroadcastReceiver extends BroadcastReceiver {
   
           @Override
           public void onReceive(Context context, Intent intent) {
               String message = intent.getStringExtra("message");
               sb.append("服务端返回消息：");
               sb.append(new Date().toLocaleString());
               sb.append("\n");
               sb.append(message);
               sb.append("\n");
               showMessage.setText(sb.toString());
   
       }
   }
   
       @Override
       protected void onDestroy() {
           Intent intent = new Intent(this, WebSocketService.class);
           stopService(intent);
           unregisterReceiver(webSocketBroadcastReceiver);
           super.onDestroy();
       }
   }

2. Service
   继承Service,在onCreate()方法里面创建WebSocketClient并和服务端进行连接。在AndroidManifest.xml中注册服务。

   public class WebSocketService extends Service {
       private IoTWebSocketClient ioTWebSocketClient;
       private Intent broadcastIntent;
   
       @Override
       public IBinder onBind(Intent intent) {
           return null;
       }
   
       @Override
       public void onCreate() {
           super.onCreate();
           broadcastIntent = new Intent();
           broadcastIntent.setAction("web_socket");
           ioTWebSocketClient = new IoTWebSocketClient(URI.create("ws://192.168.1.64:8887"));
           ioTWebSocketClient.connect();
       }
   
       @Override
       public int onStartCommand(Intent intent, int flags, int startId) {
           String message = intent.getStringExtra("message");
           if(ioTWebSocketClient.isClosing() || ioTWebSocketClient.isClosed()){
               stopSelf();
               return super.onStartCommand(intent, flags, startId);
           }
           try {
               ioTWebSocketClient.send(message);
           }catch (Exception e){
               e.printStackTrace();
           }
           return super.onStartCommand(intent, flags, startId);
       }
   
       @Override
       public void onDestroy() {
           ioTWebSocketClient.close();
           ioTWebSocketClient = null;
           super.onDestroy();
       }
   
       class IoTWebSocketClient extends WebSocketClient {
   
           IoTWebSocketClient(URI serverUri) {
               super(serverUri);
           }
   
           @Override
           public void onOpen(ServerHandshake handshakedata) {
           }
   
           @Override
           public void onMessage(String message) {
               broadcastIntent.putExtra("message", message);
               WebSocketService.this.sendBroadcast(broadcastIntent);
           }
   
           @Override
           public void onClose(int code, String reason, boolean remote) {
           }
   
           @Override
           public void onError(Exception ex) {
               stopSelf();
           }
       }
   }

   在onStartCommand()方法里面，对发送消息方法的调用进行异常捕获，是因为这时候可能服务端重启或者服务端还没有准备好，这是发送消息会抛出异常，可以根据自己的业务需求进行改进。

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