Android Best Practices 主要内容

本文用途：搜索、跟踪阅读进度、概括官方文档内容。

忽略介绍、原理、优缺点等内容。

Running in a Background Service

最有用： IntentService

流程：创建IntentService， 发送请求， 接收结果

Creating a Background Service          原文链接

1. 继承 IntentService

2.override onHandleIntent(Intent workIntent), 不用override其他callbacks 。执行任务的代码就在onHandleIntent()中。

3、添加<service>至<application>

IntentService内部有一个线程、IntentService可以相应多个请求（有队列，逐个完成）、执行完后自动停止。

Sending Work Requests to the Background Service       原文链接

1、创建explicit intent    2、startService()

Reporting Work Status

原文链接   涉及LocalBroadcastManager类

1）IntentService发送结果：1、创建Intent(可自行指定action, data uri)   2、用LocalBroadcastManager发送该intent( sendBroadcast() )

public class RSSPullService extends IntentService {
...
    /*
     * Creates a new Intent containing a Uri object
     * BROADCAST_ACTION is a custom Intent action
     */
    Intent localIntent =
            new Intent(Constants.BROADCAST_ACTION)
            // Puts the status into the Intent
            .putExtra(Constants.EXTENDED_DATA_STATUS, status);
    // Broadcasts the Intent to receivers in this app.
    LocalBroadcastManager.getInstance(this).sendBroadcast(localIntent);
...
}

2）接收结果：1、继承BroadcastReceiver  2、override onReceive()  3、新建 IntentFilter(可多个，不继承)   4、注册(下面)

// Broadcast receiver for receiving status updates from the IntentService
private class ResponseReceiver extends BroadcastReceiver
{
    // Prevents instantiation
    private DownloadStateReceiver() { }
    // Called when the BroadcastReceiver gets an Intent it's registered to receive
    @Override
    public void onReceive(Context context, Intent intent) {
...
        //Handle Intents here.
...
    }
}

4、注册receiver和intent filter：

        // Instantiates a new DownloadStateReceiver
        DownloadStateReceiver mDownloadStateReceiver =
                new DownloadStateReceiver();
        // Registers the DownloadStateReceiver and its intent filters
        LocalBroadcastManager.getInstance(this).registerReceiver(
                mDownloadStateReceiver,
                mStatusIntentFilter);
        ...

注：receiver和intent filter有多种组合，多次调用 registerReceiver() 即可（每次不同组合）。
接收到intent后，不要start activity。