吐司和广播接收器不工作

Question

你好，我试了很多次，当我点击按钮，它不显示吐司和广播接收器

下面的代码附在那里，请纠正我的错过成功运行，但当点击按钮什么都没有发生，我试图在activity_main.xml中编辑，但什么也没有发生

MainActivity.java

package com.example.myapplication;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

// broadcast a custom intent.
public void broadcastIntent(View view){
Intent intent = new Intent();
intent.setAction("com.myapplication.BOOT_COMPLETED"); sendBroadcast(intent);
}
}

MyReceiver.java

package com.example.myapplication;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

public class MyReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "Intent Detected.", Toast.LENGTH_LONG).show();
}
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myapplication">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true">
<activity android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name="MyReceiver"
android:exported="false">
<intent-filter>
<action android:name="com.myapplication.BOOT_COMPLETED">
</action>
</intent-filter>
</receiver>
</application>
</manifest>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Example of Broadcast"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:textSize="30dp" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Tutorials point "
android:textColor="#ff87ff09"
android:textSize="30dp"
android:layout_above="@+id/imageButton"
android:layout_centerHorizontal="true"
android:layout_marginBottom="40dp" />
<ImageButton
android:id="@+id/imageButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:minWidth="48dp"
android:minHeight="48dp"
tools:ignore="SpeakableTextPresentCheck" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/imageButton"
android:layout_centerHorizontal="true"
android:onClick="broadcastIntent"
android:text="broadcast_intent" />
</RelativeLayout>

Answer 1

您正在使用manifest声明的接收器.这个接收器可以从其他应用程序外部调用，或者通过一些系统事件调用。

接收器随后成为应用程序的单独入口点，这意味着系统可以启动应用程序并在应用程序当前未运行时发送广播。

如果你想在应用中触发这个接收者，你应该注册这个接收者。在您的情况下，在onCreate或onResume内的MainActivity中，如下所示

broadcastReceiver = new MyReceiver ()
Intent filter = new IntentFilter("com.myapplication.BOOT")
registerReceiver(broadcastReceiver, filter)

您还需要在onDestroy或onPause中注销它

unregisterReceiver(broadcastReceiver)

我想你应该使用上下文注册的接收器对于你想在应用程序中发送广播的用例，它几乎是相同的，除了你不需要在manifest中定义它。

更多信息在这里

Answer 2

希望这对你有帮助

import androidx.appcompat.app.AppCompatActivity;
import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends AppCompatActivity {
BroadcastReceiver br;
IntentFilter filter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
br = new MyReceiver();
filter= new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
filter.addAction(Intent.ACTION_AIRPLANE_MODE_CHANGED);

}

public void broadcastIntent(View view){
Intent intent = new Intent();
intent.setAction("com.myapplication.BOOT_COMPLETED");
sendBroadcast(intent);
this.registerReceiver(br, filter);
}
}

也见此链接https://developer.android.com/guide/components/broadcasts