Question

这是我的AndroidManifest.xml

<uses-sdk android:minSdkVersion="8" android:targetSdkVersion="18" />

    <uses-permission android:name="android.permission.GET_TASKS" />
    <uses-permission android:name="android.permission.INTERNET" />
    <application android:name="MBCRADIO" android:label="MBCRADIO">
        <activity 
                android:name=".ListenMBC" 
            android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />                
            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

并在这里监听MBC.java文件......

package org.apache.android.media;
import android.app.Activity;
import android.os.Bundle;
import java.io.IOException;
import android.widget.Button;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnPreparedListener;
import android.os.Binder;
import android.content.Intent;


public class ListenMBC extends Activity {
private static final String TAG = "radioListen";

private Button buttonPlaymbc1;    
private Button buttonPlaymbc2;
private Button buttonStopPlay;
private MediaPlayer player;

public class LocalBinder extends Binder {
    ListenMBC getService() {
        return ListenMBC.this;
    }
}

@Override
public void onCreate(Bundle icicle) {

    super.onCreate(icicle);
    setContentView(R.layout.main);

    buttonPlaymbc1 = (Button) findViewById(R.id.buttonPlaymbc1);               
    buttonPlaymbc2 = (Button) findViewById(R.id.buttonPlaymbc2);        
    buttonStopPlay = (Button) findViewById(R.id.buttonStopPlay);
    buttonStopPlay.setEnabled(false);

    buttonPlaymbc1.setOnClickListener(new OnClickListener() {
        public void onClick(View view) {
            stopPlayback();
            playRadio1();
            buttonPlaymbc1.setEnabled(false);
            if(!buttonStopPlay.isEnabled()){
                buttonStopPlay.setEnabled(true);
            }
            if(!buttonPlaymbc2.isEnabled()){
                buttonPlaymbc2.setEnabled(true);
            }
        }
    });



    buttonPlaymbc2.setOnClickListener(new OnClickListener() {
        public void onClick(View view) {
            stopPlayback();
            playRadio2();
            buttonPlaymbc2.setEnabled(false);
            if(!buttonStopPlay.isEnabled()){
                buttonStopPlay.setEnabled(true);
            }
            if(!buttonPlaymbc1.isEnabled()){
                buttonPlaymbc1.setEnabled(true);
            }
        }
    });

    buttonStopPlay.setOnClickListener(new OnClickListener() {
        public void onClick(View view) {
        stopPlayback();
        }
    });

}



private void playRadio1() {

    player = new MediaPlayer();             
    try {
        player.reset();
        player.setDataSource("http://onlineradio.globemw.net:8000");
    } catch (IllegalArgumentException e) {
        e.printStackTrace();
    } catch (IllegalStateException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    catch (Exception e) {
        Log.e(TAG, "error: " + e.getMessage(), e);
        if (player != null) {
            stopPlayback();
        }
    }

    player.prepareAsync();
    player.setOnPreparedListener(new OnPreparedListener() {

        public void onPrepared(MediaPlayer player) {
            player.start();
        }
    });
}

private void playRadio2() {
    player = new MediaPlayer();

    try {
        player.reset();
        player.setDataSource("http://onlineradio.globemw.net:8002");
    } catch (IllegalArgumentException e) {
        e.printStackTrace();
    } catch (IllegalStateException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    catch (Exception e) {
        Log.e(TAG, "error: " + e.getMessage(), e);
        if (player != null) {
            stopPlayback();
        }
    }

    player.prepareAsync();
    player.setOnPreparedListener(new OnPreparedListener() {

        public void onPrepared(MediaPlayer player) {
            player.start();
        }
    });
}

private void stopPlayback() {
    if (player!=null) {
        player.stop();
        player.release();
        player=null;
    }
    buttonStopPlay.setEnabled(false);
    if(!buttonPlaymbc1.isEnabled()){
        buttonPlaymbc1.setEnabled(true);
    }
    if(!buttonPlaymbc2.isEnabled()){
        buttonPlaymbc2.setEnabled(true);
    }
    }
}

这是MBCRADIO.java文件......

package org.apache.android.media;

import android.app.Application;

public class MBCRADIO extends Application {

@Override
public void onCreate() {
}

@Override
public void onTerminate() {
}
}

这是我的main.xml文件....

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent" 
          android:layout_height="fill_parent" 
          android:orientation="vertical" 
          android:background="@drawable/bg" >

<TextView
    android:layout_width="fill_parent"
    android:layout_height="10dp"
    android:text="@string/toptext" />

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:orientation="horizontal"
    android:baselineAligned="false" >       
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:orientation="vertical" 
            android:layout_weight="1">

                <Button
                android:id="@+id/buttonPlaymbc1"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:text="@string/play1" />

                <Button
                android:id="@+id/buttonPlaymbc2"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:text="@string/play2" />

                <Button
                android:id="@+id/buttonStopPlay"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:text="@string/stop" />

        </LinearLayout>
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:layout_weight="1"
            android:layout_gravity="center"
            android:gravity="center" >

            <ImageView android:id="@+id/ib"
            android:src="@drawable/mbc150" 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        </LinearLayout>     
</LinearLayout>

<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1" />
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1" />

<TextView
    android:layout_width="fill_parent"
    android:layout_height="20dp"
    android:gravity="center"
    android:text="@string/copy" />  
<TextView
    android:layout_width="fill_parent"
    android:layout_height="20dp"
    android:gravity="center"
    android:text="@string/copytext" />

</LinearLayout>

此代码工作正常。唯一的事情是在打开应用程序后，当我点击后退按钮时，它将进入背景模式。然后，如果我再次打开这个应用程序，它将打开另一个实例。但我想在前面打开后台应用程序。如果有任何机构对此主题感兴趣，请提供帮助。

谢谢。

Answer 1

您需要为活动的启动模式添加singleTop标志。更改你的menifest文件，为你的活动添加启动模式，如下所示：

    <activity 
            android:name=".ListenMBC" 
        android:label="@string/app_name"
         android:launchMode="singleTop"> //This is what you need to add to you manifest
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />                
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

有关详细信息，请参阅Android文档here

如果app在后台，如何在没有打开新实例的情况下在Android上打开相同的app

1 个答案: