Android实现Service后台下载Notification进度条

原文网址：http://www.obatu.com/android-service-download-notification-progressbar/

最近的项目中，有一个需求是 【后台下载+多线程+Notificaton进度条】的应用。要求有一个Service做下载服务，Notification中显示一进度条，进度条由Service来更新。
花了个把小时在网上找代码，没有一个完美的方案，最后根据片段信息，自己实现了。贴出来分享一下。

思路：

• 1. 有一个提供队列下载的Service
• 2. 该Service可以绑定，绑定的时候返回本身实例
• 3. 该Service提供方法给绑定了该Service的Activity，Activity可以调用Service的提供的方法，给Service添加队列
• 4. 该Service提供了当前下载队列的信息，信息包括下载的名称，下载进度，Activity通过接口读取队列信息用于操作，如：取消

实现：

1. 队列类

public class DownLoadQueue{



public int id; //队列id ， 该id标识了一条下载线程和Notification



public String name; // 队列名称，用于显示在Notification中



public int progress = 0; //进度，一个0-100之前的整数，标识百分比



public boolean isCancel = fale; //是否已经取消，该开关用于取消下载

2. Service类：

public class DownloadService extends Service{



private Map<integer><span class="sh_normal"> </span>downLoadQueue<span class="sh_symbol">;</span> <span class="sh_comment">//下载队列，格式：</span><id><li>
<li>
<span class="sh_keyword">private</span> <span class="sh_usertype">Binder</span><span class="sh_normal"> </span>serviceBinder <span class="sh_symbol">=</span> <span class="sh_keyword">new</span> <span class="sh_function">DownLoadServiceBinder</span><span class="sh_symbol">();</span>
</li>
<li>
<li>
<span class="sh_comment">// Activity绑定后，会自动条用这个方法</span>
</li>
<li>@Override</li>
<li>
<span class="sh_keyword">public</span> <span class="sh_usertype">IBinder</span><span class="sh_normal"> </span><span class="sh_function">onBind</span><span class="sh_symbol">(</span><span class="sh_usertype">Intent</span><span class="sh_normal"> </span>intent<span class="sh_symbol">)</span>
</li>
<li>
<span class="sh_cbracket">{</span>
</li>
<li>Log<span class="sh_symbol">.</span><span class="sh_function">d</span><span class="sh_symbol">(</span><span class="sh_string">"DownloadService"</span><span class="sh_symbol">,</span> <span class="sh_string">"onBind"</span><span class="sh_symbol">);</span>
</li>
<li>
<span class="sh_keyword">return</span> serviceBinder<span class="sh_symbol">;</span>
</li>
<li>
<span class="sh_cbracket">}</span> </li>
<li>
<li>
<span class="sh_symbol">....</span>
</li>
<li>
<li>
<span class="sh_keyword">private</span> <span class="sh_type">void</span> <span class="sh_function">startDownLoad</span><span class="sh_symbol">(</span><span class="sh_usertype">DownLoadQueue</span><span class="sh_normal"> </span>queue<span class="sh_symbol">)</span><span class="sh_cbracket">{</span>
</li>
<li>
<span class="sh_keyword">new</span> <span class="sh_function">Thread</span><span class="sh_symbol">()</span><span class="sh_cbracket">{</span>
</li>
<li>
<span class="sh_keyword">public</span> <span class="sh_type">void</span> <span class="sh_function">run</span><span class="sh_symbol">()</span><span class="sh_cbracket">{</span>
</li>
<li>
<span class="sh_comment">//进行下载工作，这里需要更新downLoadQueue中对应的queue的进度信息</span>
</li>
<li>
<span class="sh_comment">//使用Handler更新notification信息</span>
</li>
<li>
<span class="sh_symbol">....</span>
</li>
<li>
<span class="sh_cbracket">}</span>
</li>
<li>
<li>
<span class="sh_cbracket">}</span><span class="sh_symbol">.</span><span class="sh_function">start</span><span class="sh_symbol">();</span>
</li>
<li>
<span class="sh_cbracket">}</span>
</li>
<li>
<li>
<span class="sh_keyword">public</span> <span class="sh_type">void</span> <span class="sh_function">addQueue</span><span class="sh_symbol">(</span><span class="sh_usertype">DownLoadQueue</span><span class="sh_normal"> </span>queue<span class="sh_symbol">)</span><span class="sh_cbracket">{</span>
</li>
<li>
<span class="sh_keyword">this</span><span class="sh_symbol">.</span>downLoadQueue<span class="sh_symbol">.</span><span class="sh_function">add</span><span class="sh_symbol">(</span>queue<span class="sh_symbol">.</span>id<span class="sh_symbol">,</span>queue<span class="sh_symbol">);</span>
</li>
<li>
<span class="sh_keyword">this</span><span class="sh_symbol">.</span><span class="sh_function">startDownLoad</span><span class="sh_symbol">(</span>queue<span class="sh_symbol">);</span>
</li>
<li>
<span class="sh_cbracket">}</span>
</li>
<li>
<li>
<span class="sh_keyword">public</span> <span class="sh_usertype">Map</span><integer><span class="sh_normal"> </span><span class="sh_function">getQueueList</span><span class="sh_symbol">()</span><span class="sh_cbracket">{</span><li>
<span class="sh_keyword">return</span> <span class="sh_keyword">this</span><span class="sh_symbol">.</span>downLoadQueue<span class="sh_symbol">;</span>
</li>
<li>
<span class="sh_cbracket">}</span>
</li>
<li>
<li>
<span class="sh_keyword">public</span> <span class="sh_keyword">class</span><span class="sh_normal"> </span><span class="sh_classname">public</span> DownLoadServiceBinder <span class="sh_keyword">extends</span> Binder<span class="sh_cbracket">{</span>
</li>
<li>
<span class="sh_keyword">public</span> <span class="sh_usertype">DownloadService</span><span class="sh_normal"> </span><span class="sh_function">getService</span><span class="sh_symbol">()</span><span class="sh_cbracket">{</span>
</li>
<li>
<span class="sh_keyword">return</span> DownloadService<span class="sh_symbol">.</span><span class="sh_keyword">this</span><span class="sh_symbol">;</span>
</li>
<li>
<span class="sh_cbracket">}</span>
</li>
<li>
<span class="sh_cbracket">}</span>
</li></integer>
</li></id></integer>

3. Activity类：

public class DownLoadActivity{


private Handler handler = new Handler();


private DownloadService downLoadService;


private ServiceConnection serviceConnection = new ServiceConnection()


{


// 连接服务失败后，该方法被调用

@Override

public void onServiceDisconnected(ComponentName name)


{

downLoadService = null;

Toast.makeText(DownLoadActivity.this, "Service Failed.", Toast.LENGTH_LONG).show();


}


// 成功连接服务后，该方法被调用。在该方法中可以获得downLoadService对象

@Override

public void onServiceConnected(ComponentName name, IBinder service)


{


// 获得downLoadService对象

downLoadService = ((DownLoadService.DownLoadServiceBinder) service).getService();

Toast.makeText(DownLoadActivity.this, "Service Connected.", Toast.LENGTH_LONG).show();


}


}; 

@Override

public void onCreate(Bundle savedInstanceState){


super.onCreate(savedInstanceState);


Intent serviceIntent = new Intent(DownLoadActivity.this,DownloadService.class);


bindService(serviceIntent, serviceConnection, Context.BIND_AUTO_CREATE);


startService(serviceIntent);


.....


}



private void startDownLoad(){


DownLoadQueue queue = new DownLoadQueue();

queue.id = 1;

queue.name = "愤怒的小鸟"


...

downLoadService.addDownLoad(queue);


....


}


@Override

public void onDestroy(){


super.onDestroy();


unbindService(new Intent(DownLoadActivity.this,DownloadService.class));


}

4. 在Service中更新Notification时，不能过于频繁，否则会造成卡机。notification使用RemoteView来自定义Notification，加入进度条加入各种说明文字，等等。

以上文字只是简单的提及了一些思路。在项目中已经实现。下次修改完善后贴上来分享。希望能够将该功能做成一个独立的Service供大家在项目中嵌入使用。