这是一个测量声音强度的应用程序，它根据测量值设置搜索条，然后根据搜索条自动调整振铃音量。
我想在前台和后台运行此应用程序 当用户销毁它时。因为用户肯定会需要 应用程序甚至在他退出之后。我已经阅读了文档 创建一个服务，但问题是我想要完整的代码相同 应用程序销毁后在后台运行的活动。所以 非常感谢帮助。
package com.example.soundmeter;
import android.app.Activity;
import android.content.Intent;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.widget.TextView;
import android.content.Context;
import android.media.AudioManager;
import android.view.KeyEvent;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import com.example.soundmeter.R;
public class MainActivity extends Activity {
//public static boolean isService = false;
TextView mStatusView;
MediaRecorder mRecorder;
Thread runner;
private static double mEMA = 0.0;
static final private double EMA_FILTER = 0.6;
//a variable to store the seek bar from the XML file
public SeekBar volumeBar;
//an AudioManager object, to change the volume settings
private AudioManager amanager;
final Runnable updater = new Runnable(){
public void run(){
updateTv();
};
};
final Handler mHandler = new Handler();
public void onCreate(Bundle savedInstanceState) {
setContentView(R.layout.main);
super.onCreate(savedInstanceState);
mStatusView = (TextView) findViewById(R.id.status);
//startService(new Intent(MainActivity.this,BackGroundService.class));
if (runner == null)
{
runner = new Thread(){
public void run()
{
while (runner != null)
{
volumeChanger();
try
{
Thread.sleep(5000);
Log.i("Noise", "Tock");
} catch (InterruptedException e) { };
mHandler.post(updater);
}
}
};
runner.start();
Log.d("Noise", "start runner()");
}
}
public void onResume()
{
super.onResume();
startRecorder();
}
public void onPause()
{
super.onResume();
startRecorder();
//super.onPause();
//super.stopRecorder();
}
/*@Override
public void onBackPressed()
{
super.onResume();
startRecorder();
}*/
public void startRecorder(){
if (mRecorder == null)
{
mRecorder = new MediaRecorder();
mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
mRecorder.setOutputFile("/dev/null");
try
{
mRecorder.prepare();
}catch (java.io.IOException ioe) {
android.util.Log.e("[Monkey]", "IOException: " +
android.util.Log.getStackTraceString(ioe));
}catch (java.lang.SecurityException e) {
android.util.Log.e("[Monkey]", "SecurityException: " +
android.util.Log.getStackTraceString(e));
}
try
{
mRecorder.start();
}catch (java.lang.SecurityException e) {
android.util.Log.e("[Monkey]", "SecurityException: " +
android.util.Log.getStackTraceString(e));
}
//mEMA = 0.0;
}
}
/*public void stopRecorder() {
if (mRecorder != null) {
mRecorder.stop();
mRecorder.release();
mRecorder = null;
}
}*/
public void updateTv(){
double amp=getAmplitudeEMA();
mStatusView.setText(Double.toString((amp)) + " dB");
}
public double soundDb(double ampl){
double intensity=20 * Math.log10(getAmplitudeEMA() / ampl);
return intensity;
}
public double getAmplitude() {
if (mRecorder != null)
return (mRecorder.getMaxAmplitude());
else
return 0;
}
public double getAmplitudeEMA() {
double amp = getAmplitude();
mEMA = EMA_FILTER * amp + (1.0 - EMA_FILTER) * mEMA;
return mEMA;
}
public void volumeChanger()
{
volumeBar = (SeekBar) findViewById(R.id.sb_volumebar);
//get the audio manager
amanager = (AudioManager) this.getSystemService(Context.AUDIO_SERVICE);
//seek bar settings//
//sets the range between 0 and the max volume
volumeBar.setMax(amanager.getStreamMaxVolume(AudioManager.STREAM_RING));
//set the seek bar progress to 1
//volumeBar.setKeyProgressIncrement(1);
//sets the progress of the seek bar based on the system's volume
// volumeBar.setProgress(500);
if(mEMA<(double)800.00)
{
volumeBar.setProgress((int)amanager.getStreamMaxVolume(AudioManager.STREAM_RING)/5);
}
else if(mEMA<(double)15000.00)
{
volumeBar.setProgress((int)amanager.getStreamMaxVolume(AudioManager.STREAM_RING)*2/5);
}
else if(mEMA<25000.00)
{
volumeBar.setProgress((int)amanager.getStreamMaxVolume(AudioManager.STREAM_RING)*3/5);
}
else if(mEMA<50000.00)
{
volumeBar.setProgress((int)amanager.getStreamMaxVolume(AudioManager.STREAM_RING)*4/5);
}
else
{
volumeBar.setProgress((int)amanager.getStreamMaxVolume(AudioManager.STREAM_RING));
}
//register OnSeekBarChangeListener, so that the seek bar can change the volume
volumeBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener()
{
@Override
public void onStopTrackingTouch(SeekBar seekBar)
{
}
@Override
public void onStartTrackingTouch(SeekBar seekBar)
{
}
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser)
{
int index=volumeBar.getProgress();
//change the volume, displaying a toast message containing the current volume and playing a feedback sound
amanager.setStreamVolume(AudioManager.STREAM_RING, index, AudioManager.FLAG_SHOW_UI);
}
});
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
//if one of the volume keys were pressed
if(keyCode == KeyEvent.KEYCODE_VOLUME_DOWN || keyCode == KeyEvent.KEYCODE_VOLUME_UP)
{
//change the seek bar progress indicator position
volumeBar.setProgress(amanager.getStreamVolume(AudioManager.STREAM_RING));
}
if (keyCode == KeyEvent.KEYCODE_BACK) {
moveTaskToBack(true);
return true;
}
//propagate the key event
return super.onKeyDown(keyCode, event);
}
}
答案 0 :(得分：0)
让测量代码始终监听服务并让它更新共享首选项。
然后，所有活动需要做的是收听共享首选项的更改并相应地更新UI。
显然，您可以使用任意数量的机制来允许活动响应服务更改，但我认为监听共享首选项更改可能最容易开始。
listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
//update ui if your key was updated
}
};
prefs.registerOnSharedPreferenceChangeListener(listener);
答案 1 :(得分：0)
我已经找到了另一种方法。 广播接收器可以在主要活动中与广播服务同步使用。