【学习】Service与Activity之间通信的几种方式

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原文地址

通过broadcast(广播)的形式

当我们的进度发生变化的时候我们发送一条广播，然后在Activity的注册广播接收器，接收到广播之后更新ProgressBar,代码如下

package com.example.communication;  import android.app.Activity;  import android.content.BroadcastReceiver;  import android.content.Context;  import android.content.Intent;  import android.content.IntentFilter;  import android.os.Bundle;  import android.view.View;  import android.view.View.OnClickListener;  import android.widget.Button;  import android.widget.ProgressBar;    public class MainActivity extends Activity {      private ProgressBar mProgressBar;      private Intent mIntent;      private MsgReceiver msgReceiver;            @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_main);                    //动态注册广播接收器          msgReceiver = new MsgReceiver();          IntentFilter intentFilter = new IntentFilter();          intentFilter.addAction("com.example.communication.RECEIVER");          registerReceiver(msgReceiver, intentFilter);                    mProgressBar = (ProgressBar) findViewById(R.id.progressBar1);          Button mButton = (Button) findViewById(R.id.button1);          mButton.setOnClickListener(new OnClickListener() {                            @Override              public void onClick(View v) {                  //启动服务                  mIntent = new Intent("com.example.communication.MSG_ACTION");                  startService(mIntent);              }          });                }              @Override      protected void onDestroy() {          //停止服务          stopService(mIntent);          //注销广播          unregisterReceiver(msgReceiver);          super.onDestroy();      }          /**      * 广播接收器      * @author len      *      */      public class MsgReceiver extends BroadcastReceiver{            @Override          public void onReceive(Context context, Intent intent) {              //拿到进度，更新UI              int progress = intent.getIntExtra("progress", 0);              mProgressBar.setProgress(progress);          }      }  }

package com.example.communication;    import android.app.Service;  import android.content.Intent;  import android.os.IBinder;    public class MsgService extends Service {      /**      * 进度条的最大值      */      public static final int MAX_PROGRESS = 100;      /**      * 进度条的进度值      */      private int progress = 0;            private Intent intent = new Intent("com.example.communication.RECEIVER");              /**      * 模拟下载任务，每秒钟更新一次      */      public void startDownLoad(){          new Thread(new Runnable() {                            @Override              public void run() {                  while(progress < MAX_PROGRESS){                      progress += 5;                                            //发送Action为com.example.communication.RECEIVER的广播                      intent.putExtra("progress", progress);                      sendBroadcast(intent);                                            try {                          Thread.sleep(1000);                      } catch (InterruptedException e) {                          e.printStackTrace();                      }                                        }              }          }).start();      }                @Override      public int onStartCommand(Intent intent, int flags, int startId) {          startDownLoad();          return super.onStartCommand(intent, flags, startId);      }            @Override      public IBinder onBind(Intent intent) {          return null;      }    }

总结:

Activity调用bindService (Intent service, ServiceConnection conn, int flags)方法，得到Service对象的一个引用，这样Activity可以直接调用到Service中的方法，如果要主动通知Activity，我们可以利用回调方法
Service向Activity发送消息，可以使用广播，当然Activity要注册相应的接收器。比如Service要向多个Activity发送同样的消息的话，用这种方法就更好

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