如何从Android服务获取应用程序上下文？

Question

我有一个正在运行和监听麦克风输入的Android服务.我希望它在满足某个标准时启动活动.为了创建一个Intent,我需要应用程序上下文.我怎么才能得到它？

Intent i = new Intent(ctx, SONR.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
ctx.startActivity(i);

以上行不会启动我的活动.

这是我的构造函数

public SONRClient(Context c, AudioRecord ar, int buffsize, final AudioManager am) {
    theAudioManager = am;
    theaudiorecord = ar;
    bufferSize = buffsize;
    ctx = c;
    CLIENT_ON = true;
}

这是我的onCreate

@Override
public void onCreate() {
    try {
        // LogFile.MakeLog("\n\nSONRClient CREATED");
        clientStopReceiver = new StopReceiver();
        ctx.registerReceiver(clientStopReceiver, 
            new IntentFilter(SONR.DISCONNECT_ACTION));
        myByteReceiver = new SONRByteReceiver();
        theListener = new MicSerialListener(
            theaudiorecord, bufferSize, myByteReceiver);
        theApplication = getApplication();
    } catch (Exception e) {
        e.printStackTrace();
        ErrorReporter.getInstance().handleException(e);
    }
}

myByteReceiver通过音频输入监听信号.当它找到匹配的信号时,我希望它启动一个活动.

private class SONRByteReceiver implements ByteReceiver {
    private long lastplaytime = 0;
    private long lastmutetime = 0;
    private long lastskiptime = 0;
    private long lastvolutime = 0;
    private long lastbacktime = 0;

    public void receiveByte(int receivedByte) {
        try {
            theKeyEvent = -1;

            if (ismuted) {
                if (receivedByte != MUTE) {
                    volume = 0;
                    ismuted = false;
                }
            }

            switch (receivedByte) {

            case SONR_HOME:
                Log.d(TAG, "HOME");

                Intent i = new Intent(ctx, SONR.class);
                i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                theApplication.startActivity(i);

                break;
            default:
                Log.d(TAG, "default");
                Log.d(TAG,"RECEIVED " + receivedByte);
                // LogFile.MakeLog("RECEIVED " + receivedByte);
                break;
            }

            if (theKeyEvent >= 0) {
                sendbroadcast();
            }
        } catch (Exception e) {
            e.printStackTrace();
            ErrorReporter.getInstance().handleException(e);
        }
    }
}

这是堆栈跟踪

java.lang.NullPointerException
    at com.sonrlabs.test.sonr.SONRClient$SONRByteReceiver.receiveByte(SONRClient.java:320)
    at com.sonrlabs.test.sonr.AudioProcessor.processSample(AudioProcessor.java:145)
    at com.sonrlabs.test.sonr.AudioProcessor.run(AudioProcessor.java:58)

320行是 theApplication.startActivity(i);

Answer 1

您可以getApplicationContext()在服务内部使用以获取应用程序上下文。

尝试使用

getApplication().startActivity(i);

android从服务开始活动

Answer 2

每个服务都有自己的上下文，只需使用它即可。您不需要向服务传递活动的上下文。

服务中不需要活动上下文。

Intent i = new Intent(ctx, SONR.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(i);

只需按照您在“活动”中所做的操作即可

Service 和 Activity 都是 Context 的子类。

Answer 3

ctx.getApplicationContext().startActivity(i)

繁荣。