android - setAction() 对 intent (Broadcast) 做了什么

Question

intent(Service)中setAction()是做什么的

我不太明白 setAction () 的作用，我主要是在“服务到 Activity 数据传递”示例中找到它。字符串可以自由设置吗？它到底有什么作用？

When a broadcast intent is created, it must include an ACTION STRING in addition to optional data and a category string. As with standard intents, data is added to a broadcast intent using key-value pairs in conjunction with the putExtra() method of the intent object. The optional category string may be assigned to a broadcast intent via a call to the addCategory() method.

The action string, which identifies the broadcast event, must be unique and typically uses the application’s Java package name syntax. For example, the following code fragment creates and sends a broadcast intent including a unique action string and data:

 Intent intent = new Intent();
intent.setAction("com.example.Broadcast");
intent.putExtra("HighScore", 1000); sendBroadcast(intent);

我见过的另一种变体是:

 Intent broadcastIntent = new Intent();

            broadcastIntent.setAction("com.truiton.broadcast.string");
            broadcastIntent.putExtra("Data", "Broadcast Data");
            sendBroadcast(broadcastIntent);

            try {
               Thread.sleep(1000);
            } catch (InterruptedException e) {
               e.printStackTrace();
            }
            broadcastIntent.setAction("com.truiton.broadcast.integer");
            broadcastIntent.putExtra("Data", 10);
            sendBroadcast(broadcastIntent);

            try {
               Thread.sleep(1000);
            } catch (InterruptedException e) {
               e.printStackTrace();
            }
            broadcastIntent .setAction("com.truiton.broadcast.arraylist");
            broadcastIntent.putExtra("Data", mList);
            sendBroadcast(broadcastIntent);

这看起来更像是识别传入的数据类型。

它是指识别事件、传入的数据类型、操作 还是每个Intent 创建？可以放生吗？

Answer 1

使用 <action>标签内 <activity>在 Manifest.xml 文件中设置操作的标记与在 java 文件中使用 intent.setAction 以编程方式设置操作相同。

这些通常用于广播接收器。

下面是一个xml例子:

<receiver android:name="MyReceiver" >
            <intent-filter>
                <action android:name="com.example.SendBroadcast" >
                </action>
<action android:name="android.intent.action.ACTION_POWER_DISCONNECTED" >          
                </action>
            </intent-filter>
        </receiver>

但是当您希望 BroadCastReceiver 以编程方式注册和取消注册时，可以使用 setAction()。

Intent intent = new Intent();
          intent.setAction("com.example.SendBroadcast");
          intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
          sendBroadcast(intent);

有关更多信息，请查看:http://www.techotopia.com/index.php/Android_Broadcast_Intents_and_Broadcast_Receivers