Android~Service+BroadcastReceiver使用

由于项目需要，我们有时候需要在service中处理耗时操作，然后将结果发送给activity以更新状态。通常情况下，只需要在一个service与一个activity之间通信，这种情况下，我们使用最多的是通过回调接口。具体做法是在service中定义一个接口，在activity中实现改接口，并通过bindservice来传入。当需要将service中的结果一次发送给多个activity时，我们又该如何实现呢？经过检索，存在三种实现的方式，分别是回调接口、广播接收者和观察者模式。
本文主要讲解比较推荐的方式——广播接收者。通过广播接收者，在service中执行完耗时操作后，将结果以广播的形式发送，在所有的activity中注册广播，接收到结果后更新UI，这种方式比较简单。因为耗时的操作结果不需要以handler的方式发送到主线程，可以直接在子线程中发送广播，接收者始终运行在主线程中。

Service.java

package com.example.servicecallback;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;

public class ContentService extends Service {


  @Override
  public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub
    return new LocalBinder();
  }

  @Override
  public void onCreate() {
    // TODO Auto-generated method stub
    super.onCreate();
  }

  public final class LocalBinder extends Binder {
    public ContentService getService() {
      return ContentService.this;
    }
  }

  public void asyncSendPerson(final String name) {
    // 休息5秒，模拟异步任务
    new Thread(new Runnable() {
      @Override
      public void run() {
        try {
          Thread.sleep(5000);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        //可以在子线程中直接发送广播
        sendContentBroadcast(name);
      }
    }).start();
  }

  /**
   * 发送广播
   * @param name
   */
  protected void sendContentBroadcast(String name) {
    // TODO Auto-generated method stub
    Intent intent=new Intent();
    intent.setAction("com.example.servicecallback.content");
    intent.putExtra("name", name);
    sendBroadcast(intent);
  }
}

MainActivity.java

package com.example.servicecallback;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;

public class MainActivity extends Activity {

  private MyServiceConn conn;
  private TextView mContent;
  private ContentReceiver mReceiver;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    conn = new MyServiceConn();
    bindService(new Intent(this, ContentService.class), conn,
        BIND_AUTO_CREATE);

    mContent = (TextView) findViewById(R.id.content);

    this.findViewById(R.id.button1).setOnClickListener(
        new OnClickListener() {
          @Override
          public void onClick(View v) {
            // TODO Auto-generated method stub
            startActivity(new Intent(MainActivity.this,
                OtherActivity.class));
          }
        });


    doRegisterReceiver();
  }

  /**
   * 注册广播接收者
   */
  private void doRegisterReceiver() {
    mReceiver=new ContentReceiver();
    IntentFilter filter = new IntentFilter(
        "com.example.servicecallback.content");
    registerReceiver(mReceiver, filter);
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
  }

  public class MyServiceConn implements ServiceConnection {

    @Override
    public void onServiceConnected(ComponentName name, IBinder binder) {
      // service = ((LocalBinder) binder).getService();
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
      // TODO Auto-generated method stub
      // service = null;
    }
  }

  @Override
  protected void onDestroy() {
    // TODO Auto-generated method stub
    super.onDestroy();
    unbindService(conn);
    if (mReceiver!=null) {
      unregisterReceiver(mReceiver);
    }
  }

  public class ContentReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
      String name = intent.getStringExtra("name");
      Person person = new Person();
      person.setName(name);
      mContent.setText(person.toString());
    }
  }
}

OtherActivity.java

package com.example.servicecallback;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.example.servicecallback.ContentService.LocalBinder;

public class OtherActivity extends Activity {

  private ContentService service;
  private TextView mContent;
  private Button mSubmit;
  private EditText mEditText;
  private ServiceConnection conn;
  private ContentReceiver mReceiver;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.other);

    mEditText = (EditText) findViewById(R.id.edittext);
    mSubmit = (Button) findViewById(R.id.button1);
    mContent = (TextView) findViewById(R.id.content);

    mSubmit.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        String name = mEditText.getText().toString();
        service.asyncSendPerson(name);
      }
    });


    conn=new MyServiceConn();
    bindService(new Intent(OtherActivity.this, ContentService.class), conn,
        BIND_AUTO_CREATE);

    doRegisterReceiver();
  }

  private void doRegisterReceiver() {
    mReceiver=new ContentReceiver();
    IntentFilter filter = new IntentFilter(
        "com.example.servicecallback.content");
    registerReceiver(mReceiver, filter);
  }

  public final class MyServiceConn implements ServiceConnection {
    @Override
    public void onServiceConnected(ComponentName name, IBinder binder) {
      service = ((LocalBinder) binder).getService();
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
      service = null;
    }
  }

  @Override
  protected void onDestroy() {
    super.onDestroy();
    unbindService(conn);
    if (mReceiver!=null) {
      unregisterReceiver(mReceiver);
    }
  }

  public class ContentReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
      String name = intent.getStringExtra("name");
      Person person = new Person();
      person.setName(name);
      mContent.setText(person.toString());
    }
  }
}

Android~Service+BroadcastReceiver使用

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