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  • 方法中启动的Activity动态注册广播,此新启动的Activity接收不到此方法后续发出的广播

    今天写音乐播放器歌词展示界面(这个播放器的代码可能周末再释放出来吧,有点乱,需要整理),本来想点击列表框后弹出展示歌词Activity,同时接收方法后续代码中发出的广播,但却一直接收不到,调整几次后,觉得可能方法X中新启动Activity,在其这个新的Activity中的onCreate方法动态注册广播,此时这个新启动的Activity接收不到此方法X后续发出的广播
    最终测试发现果真如此
    测试代码如下:

     1     package com.example.myfirstapp;
     2 
     3     import android.app.Activity;
     4     import android.content.Intent;
     5     import android.os.Bundle;
     6     import android.view.View;
     7 
     8     public class FirstActivity extends Activity {
     9         
    10         /* (非 Javadoc)
    11          * Title: onCreate
    12          * Description:
    13          * @param savedInstanceState
    14          * @see android.app.Activity#onCreate(android.os.Bundle)
    15          */
    16         @Override
    17         protected void onCreate(Bundle savedInstanceState) {
    18             super.onCreate(savedInstanceState);
    19             setContentView(R.layout.firstactivity);
    20             System.out.println("SecondActivity");
    21         }
    22         
    23         public void openActivity2( View view ) {
    24             Intent mIntent = new Intent(this, SecondActivity.class);
    25             startActivity(mIntent);
    26             Intent broadcastIntent = new Intent("com.example.firstactivity");
    27             sendBroadcast(broadcastIntent);
    28         }
    29         
    30     }
    FirstActivity

    布局:

     1     <?xml version="1.0" encoding="utf-8"?>
     2     <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     3         android:layout_width="match_parent"
     4         android:layout_height="match_parent"
     5         android:orientation="vertical" >
     6 
     7         <Button
     8             android:layout_width="fill_parent"
     9             android:layout_height="wrap_content"
    10             android:onClick="openActivity2"
    11             android:text="Open" />
    12 
    13     </LinearLayout>
    firstactivity

    SecondActivity中的代码:

     1     package com.example.myfirstapp;
     2 
     3     import java.util.Date;
     4 
     5     import android.app.Activity;
     6     import android.content.BroadcastReceiver;
     7     import android.content.Context;
     8     import android.content.Intent;
     9     import android.content.IntentFilter;
    10     import android.os.Bundle;
    11     import android.view.View;
    12     import android.widget.TextView;
    13 
    14     public class SecondActivity extends Activity {
    15         
    16         private TextView second_tv1 = null;
    17         private SecondBoradCast mSecondBoradCast = new SecondBoradCast();
    18         
    19         /* (非 Javadoc)
    20          * Title: onCreate
    21          * Description:
    22          * @param savedInstanceState
    23          * @see android.app.Activity#onCreate(android.os.Bundle)
    24          */
    25         @Override
    26         protected void onCreate(Bundle savedInstanceState) {
    27             super.onCreate(savedInstanceState);
    28             setContentView(R.layout.secondactivity);
    29             second_tv1 = (TextView)findViewById(R.id.second_tv1);
    30             registerReceiver(mSecondBoradCast, new IntentFilter("com.example.firstactivity"));
    31             System.out.println("SecondActivity");
    32         }
    33         
    34         public void sendBroadCast( View view ) {
    35             Intent broadcastIntent = new Intent("com.example.firstactivity");
    36             sendBroadcast(broadcastIntent);
    37         }
    38         
    39         /* (非 Javadoc)
    40          * Title: onDestroy
    41          * Description:
    42          * @see android.app.Activity#onDestroy()
    43          */
    44         @Override
    45         protected void onDestroy() {
    46             super.onDestroy();
    47             if( mSecondBoradCast != null ) {
    48                 unregisterReceiver(mSecondBoradCast);
    49                 mSecondBoradCast = null;
    50             }
    51         }
    52         
    53         public class SecondBoradCast extends BroadcastReceiver {
    54 
    55             /* (非 Javadoc)
    56              * Title: onReceive
    57              * Description:
    58              * @param context
    59              * @param intent
    60              * @see android.content.BroadcastReceiver#onReceive(android.content.Context, android.content.Intent)
    61              */
    62             @Override
    63             public void onReceive(Context context, Intent intent) {
    64                 System.out.println(new Date());
    65                 second_tv1.setText("接收成功");
    66             }
    67             
    68         }
    69         
    70     }
    SecondActivity

    布局:

     1     <?xml version="1.0" encoding="utf-8"?>
     2     <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     3         android:layout_width="match_parent"
     4         android:layout_height="match_parent"
     5         android:orientation="vertical" >
     6 
     7         <Button
     8             android:layout_width="fill_parent"
     9             android:layout_height="wrap_content"
    10             android:onClick="sendBroadCast"
    11             android:text="Send" />
    12 
    13         <TextView
    14             android:id="@+id/second_tv1"
    15             android:layout_width="fill_parent"
    16             android:layout_height="fill_parent"
    17             android:text="Just Test"
    18             android:textColor="#f000" />
    19 
    20     </LinearLayout>
    secondactivity

    运行此项目,点击第一个Activity中的Open按钮后,出现界面

    点击Send按钮,发送广播,界面中的TextView改变文字

    在点击了Send按钮之后,才接收到广播

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  • 原文地址:https://www.cnblogs.com/creasylai19/p/3771562.html
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