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安卓开发_广播机制_发送自定义广播

article 2024/11/18 11:39:26

安卓开发_广播机制_发送自定义广播

发送标准广播
发送有序广播
参考

发送标准广播

新建一个MyBroadcastReceiver用于接收广播, 代码如下:

class MyBroadcastReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        Toast.makeText(context, "received in MyBroadcastReceiver", Toast.LENGTH_SHORT).show()
    }
}

再AndroidManifest.xml中修改MyBroadcastReceiver, 代码如下:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    ...

    <application
        ...>

        <receiver
            android:name=".MyBroadcastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.example.broadcasttest.MY_BROADCAST" />
            </intent-filter>
        </receiver>
        ...
    </application>

</manifest>

定义一个用于发送广播的按钮, 代码如下:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <Button
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Send Broadcast"
        />
</LinearLayout>

给按钮加入发送自定义广播的逻辑, 代码如下:

class MyActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMyBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMyBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // 发送标准广播
        binding.button1.setOnClickListener {
            val intent = Intent("com.example.broadcasttest.MY_BROADCAST")

            // 指定要发送给哪个程序后, 才会变成显示广播, 静态注册的Broadcast才可以接收到这条广播
            intent.setPackage(packageName)
            sendBroadcast(intent)
        }
    }
}

发送有序广播

再创建一个新的BroadcastReceiver, 代码如下:

class AnotherBroadcastReceiver : BroadcastReceiver() {

    override fun onReceive(context: Context, intent: Intent) {
        Toast.makeText(context, "received in AnotherBroadcastReceiver", Toast.LENGTH_SHORT).show()
    }

}

在AndroidManifest.xml中修改AnotherBroadcastReceiver，代码如下:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    ...

    <application
        ...>
        <receiver
            android:name=".AnotherBroadcastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.example.broadcasttest.MY_BROADCAST" />
            </intent-filter>
        </receiver>

        ...
    </application>

</manifest>

此时点击"Send Broadcast", 会分别弹出俩次提示信息.

接下来再定义一个按钮并添加逻辑, 代码如下:

class MyActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMyBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMyBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // 发送有序广播
        binding.button2.setOnClickListener{
            val intent = Intent("com.example.broadcasttest.MY_BROADCAST")
            // 第二个参数是一个与权限相关的字符串
            sendOrderedBroadcast(intent, null)
        }
    }
}

设定BroadcastReceiver的先后顺序, 代码如下:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        ...>
        <receiver
            ...>
            <intent-filter android:priority="100">
                ...
            </intent-filter>
        </receiver>
    </application>

</manifest>

修改MyBroadcastReceiver中的代码, 代码如下所示:

class MyBroadcastReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        Toast.makeText(context, "received in MyBroadcastReceiver", Toast.LENGTH_SHORT).show()
        // 截断广播
        abortBroadcast()
    }
}