我尝试将我的应用程序的一部分转换为服务，因为它需要在后台运行。现在，一个按钮应该在点击时启动和停止服务：
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_aim_start);
tThis = this;
calc.init();
status = (TextView) findViewById(R.id.statusView);
output = (TextView) findViewById(R.id.lbl_output);
final Intent intent = new Intent(this, AIMService.class);
startButton = (Button) findViewById(R.id.start_aim);
startButton.setOnClickListener(new View.OnClickListener (){
public void onClick(View v) {
if (!func) {
func = true;
startButton.setText("Stop AIM");
status.setText("AIM-Started");
tThis.startService(intent); //I read somewhere that it would need a
//context, but it didn't work
} else {
func = false;
startButton.setText("Start AIM");
tThis.stopService(intent);
}
}
});
但是，现在我收到以下错误：
FATAL EXCEPTION: main
Process: com.protonmail.fabian.schneider.aim, PID: 6081
java.lang.RuntimeException: Unable to start service com.protonmail.fabian.schneider.aim.AIMService@1dacca22 with Intent { cmp=com.protonmail.fabian.schneider.aim/.AIMService }: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Message android.app.IntentService$ServiceHandler.obtainMessage()' on a null object reference
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3336)
at android.app.ActivityThread.access$2200(ActivityThread.java:177)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1530)
t android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5912)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Message android.app.IntentService$ServiceHandler.obtainMessage()' on a null object reference
服务在清单中声明。 清单：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.protonmail.fabian.schneider.aim">
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".AIM_start"
android:label="AIM"
android:configChanges = "orientation"
android:screenOrientation="portrait">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".AIMService" />
</application>
</manifest>
服务：
公共类AIMService扩展了IntentService {
private SoundPool soundPool;
private AudioManager audioManager;
private static final int max_streams = 1;
private static final int streamType = AudioManager.STREAM_MUSIC;
boolean loaded;
public static String strengthArr[] = new String[4];
static {
strengthArr[0] = "90,110,90,110";
strengthArr[1] = "50,89,111,150";
strengthArr[2] = "0,49,151,200";
strengthArr[3] = "-50,-1,201,-250";
}
static String downURL = "http://services.swpc.noaa.gov/text/goes-magnetometer-primary.txt";
static String errPatt = "-1.00e+05";
private float volume;
private int strengthSound[] = new int[5];
@Override
public void onCreate(){
System.out.println("started audio initialization");
//AUDIO
audioManager = (AudioManager) getSystemService(AUDIO_SERVICE);
float currentVolumeIndex = (float) audioManager.getStreamVolume(streamType);
float maxVolumeIndex = (float) audioManager.getStreamMaxVolume(streamType);
this.volume = currentVolumeIndex/maxVolumeIndex;
//this.setVolumeControlStream(streamType);
if(Build.VERSION.SDK_INT >= 21) {
AudioAttributes audioAttrib = new AudioAttributes.Builder()
.setUsage(AudioAttributes.USAGE_GAME)
.setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
.build();
SoundPool.Builder builder = new SoundPool.Builder();
builder.setAudioAttributes(audioAttrib).setMaxStreams(max_streams);
this.soundPool = builder.build();
} else{
this.soundPool = new SoundPool(max_streams, AudioManager.STREAM_MUSIC, 0);
}
//Sound pool load complete
this.soundPool.setOnLoadCompleteListener(new SoundPool.OnLoadCompleteListener() {
@Override
public void onLoadComplete(SoundPool soundPool, int sampleId, int status) {
loaded = true;
System.out.println("finished loading resources");
//publishProgress("finished loading resources");
//SoundPool.Builder(new SoundPool.Builder()).play(strengthSound[0],volume,volume,1,0,1f);
/*MediaPlayer mediaPlayer = MediaPlayer.create(this, R.raw.strength0);
MediaPlayer mediaPlayer2 = MediaPlayer.create()
mediaPlayer.start();*/
}
});
System.out.println("starting tone init");
this.strengthSound[0] = this.soundPool.load(this, R.raw.strength0,1);
this.strengthSound[1] = this.soundPool.load(this, R.raw.strength1,1);
this.strengthSound[2] = this.soundPool.load(this, R.raw.strength2,1);
this.strengthSound[3] = this.soundPool.load(this, R.raw.strength3,1);
this.strengthSound[4] = this.soundPool.load(this, R.raw.strength4,1);
System.out.println("fin tone init");
}
public AIMService(){
super("AIMService");
}
@Override
protected void onHandleIntent (Intent intent) {
//WORK
while (true) {
System.out.println("before publishProgress Update");
//publishProgress("Calculation Started");
AIMService.dataImport dI;
try {
dI = new AIMService.dataImport(downURL);
String calcData;
calcData = dI.download();
System.out.println(calcData);
AIMService.preAnalysis pA;
pA = new AIMService.preAnalysis(calcData);
boolean dateOk;
dateOk = pA.preanalyse();
if (dateOk) {
System.out.println("Data Date is okay");
//call last line downloader
dI = new AIMService.dataImport(downURL);
String lastLine;
lastLine = dI.downloadLast();
if (!lastLine.contains(errPatt)) {
//data is ok
System.out.println("Current data is okay");
System.out.println("Current data: " + lastLine);
System.out.println("Starting analysis");
AIMService.analyse an = new AIMService.analyse(lastLine);
int strength;
strength = an.analyseData();
if (strength != -1) {
System.out.println("Strength: " + strength);
//outputText(Integer.toString(strength));
publishProgress(Integer.toString(strength));
//return Integer.toString(strength);
} else {
System.out.println("Strength not found");
//send signal for out of scope to output
publishProgress("-1");
//return "-1";
}
} else {
System.out.println("Current data is not okay");
publishProgress("Current data is not okay");
//send signal for satellite down to output
publishProgress("-1");
//return "-1";
}
} else {
System.out.println("Data Date not okay");
publishProgress("Data Date not okay");
//send signal for satellite down to output
publishProgress("-1");
//return "-1";
}
//catch statements
} catch (MalformedURLException e) {
System.out.println("MalformedUrlException for dI allocation");
} catch (IOException e) {
System.out.println("IOException in dI alloc");
//check inet conn/send satellite down to output
return;
}
//return "ERROR";
}
}
我做错了什么？
答案 0 :(得分：0)
您使用IntentService，它会创建一个单独的Thread来执行命令中的任务，然后它会在它之后立即终止。您应该在onHandleIntent（Intent intent）方法中完成所有工作。 在您的情况下使用普通服务，而不是IntentService。
答案 1 :(得分：0)
仅为完成主题;以下是答案摘要：
像Alex Shutov告诉我的那样，我将Intent Service更改为服务。 我按照官方文档完成了这项工作： Documentation对所有对代码和/或项目感兴趣的人： GitHub AIM