Question

我是android新手。我正在尝试创建一个非常基本的后台服务。 Logcat的错误粘贴在下面。我想在我的标签上运行它。该应用程序打开然后变为空白，并显示消息“不幸的是，后台服务已停止”。任何帮助将不胜感激。

我的主要活动

package com.example.backgroundservice;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.widget.TextView;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    TextView view = new TextView(this);
    view.setText("Service Test");
    Intent i = new Intent();
    i.setClassName("com.example.backgroundservice", "com.example.backgroundservice.MyService");
    bindService(i, null, Context.BIND_AUTO_CREATE);
    this.startService(i);
    setContentView(view);
}

}

我的服务类

package com.example.backgroundservice;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;


public class MyService extends Service {

    String tag="TestService";

    @Override
    public void onCreate(){
        super.onCreate();
        Toast.makeText(this, "Service Created..", Toast.LENGTH_LONG).show();
        Log.e(tag, "Service Created..");
    }

    @SuppressWarnings("deprecation")
    @Override
    public void onStart(Intent intent, int startId){
        super.onStart(intent, startId);
        Log.e(tag, "Service started..");
    }

    @Override
    public void onDestroy(){
        super.onDestroy();
        Toast.makeText(this, "Service destroyed..", Toast.LENGTH_LONG).show();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }

}

清单文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.backgroundservice"
    android:versionCode="1"
    android:versionName="1.0" >

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

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <service class="com.example.backgroundservice.MyService" 
            android:name="com.example.backgroundservice.MyService"
            android:exported="false">
             <intent-filter>
                <action android:value="com.example.backgroundservice.MyService.MY_SERVICE"
                    android:name="com.example.backgroundservice.MyService" />
            </intent-filter>
        </service>        
        <activity
            android:name="com.example.backgroundservice.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

LogCat o / p：

02-02 14:54:34.805: E/AndroidRuntime(18988): FATAL EXCEPTION: main
02-02 14:54:34.805: E/AndroidRuntime(18988): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.backgroundservice/com.example.backgroundservice.MainActivity}: java.lang.IllegalArgumentException: connection is null
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2245)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.ActivityThread.access$700(ActivityThread.java:150)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.os.Looper.loop(Looper.java:137)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.ActivityThread.main(ActivityThread.java:5279)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at java.lang.reflect.Method.invokeNative(Native Method)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at java.lang.reflect.Method.invoke(Method.java:511)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at dalvik.system.NativeStart.main(Native Method)
02-02 14:54:34.805: E/AndroidRuntime(18988): Caused by: java.lang.IllegalArgumentException: connection is null
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.ContextImpl.bindService(ContextImpl.java:1759)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.ContextImpl.bindService(ContextImpl.java:1751)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.content.ContextWrapper.bindService(ContextWrapper.java:480)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at com.example.backgroundservice.MainActivity.onCreate(MainActivity.java:18)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.Activity.performCreate(Activity.java:5276)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
02-02 14:54:34.805: E/AndroidRuntime(18988):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
02-02 14:54:34.805: E/AndroidRuntime(18988):    ... 11 more

谢谢大家的建议。我在bindService（）中处理'Null'。我的服务现在工作正常，但我确实在跟踪中看到了以下内容。我没有得到它，非常感谢您在调试时的任何帮助。

跟踪：

02-02 19:04:05.120: E/ActivityThread(21488): Activity com.example.backgroundservice.MainActivity has leaked ServiceConnection com.example.backgroundservice.MainActivity$1@423d2220 that was originally bound here
02-02 19:04:05.120: E/ActivityThread(21488): android.app.ServiceConnectionLeaked: Activity com.example.backgroundservice.MainActivity has leaked ServiceConnection com.example.backgroundservice.MainActivity$1@423d2220 that was originally bound here
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.LoadedApk$ServiceDispatcher.<init>(LoadedApk.java:974)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.LoadedApk.getServiceDispatcher(LoadedApk.java:868)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.ContextImpl.bindService(ContextImpl.java:1762)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.ContextImpl.bindService(ContextImpl.java:1751)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.content.ContextWrapper.bindService(ContextWrapper.java:480)
02-02 19:04:05.120: E/ActivityThread(21488):    at com.example.backgroundservice.MainActivity.onCreate(MainActivity.java:26)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.Activity.performCreate(Activity.java:5276)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.ActivityThread.access$700(ActivityThread.java:150)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.os.Looper.loop(Looper.java:137)
02-02 19:04:05.120: E/ActivityThread(21488):    at android.app.ActivityThread.main(ActivityThread.java:5279)
02-02 19:04:05.120: E/ActivityThread(21488):    at java.lang.reflect.Method.invokeNative(Native Method)
02-02 19:04:05.120: E/ActivityThread(21488):    at java.lang.reflect.Method.invoke(Method.java:511)
02-02 19:04:05.120: E/ActivityThread(21488):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
02-02 19:04:05.120: E/ActivityThread(21488):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
02-02 19:04:05.120: E/ActivityThread(21488):    at dalvik.system.NativeStart.main(Native Method)
02-02 19:04:30.075: E/TestService(21488): Service started..
02-02 19:04:31.850: D/GestureDetector(21488): [Surface Touch Event] mSweepDown False, mLRSDCnt : -1 mTouchCnt : 10 mFalseSizeCnt:0
02-02 19:04:32.750: D/AbsListView(21488): Get MotionRecognitionManager
02-02 19:04:34.145: E/ActivityThread(21488): Activity com.example.backgroundservice.MainActivity has leaked ServiceConnection com.example.backgroundservice.MainActivity$1@4241f808 that was originally bound here
02-02 19:04:34.145: E/ActivityThread(21488): android.app.ServiceConnectionLeaked: Activity com.example.backgroundservice.MainActivity has leaked ServiceConnection com.example.backgroundservice.MainActivity$1@4241f808 that was originally bound here
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.LoadedApk$ServiceDispatcher.<init>(LoadedApk.java:974)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.LoadedApk.getServiceDispatcher(LoadedApk.java:868)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.ContextImpl.bindService(ContextImpl.java:1762)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.ContextImpl.bindService(ContextImpl.java:1751)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.content.ContextWrapper.bindService(ContextWrapper.java:480)
02-02 19:04:34.145: E/ActivityThread(21488):    at com.example.backgroundservice.MainActivity.onCreate(MainActivity.java:26)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.Activity.performCreate(Activity.java:5276)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.ActivityThread.access$700(ActivityThread.java:150)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.os.Looper.loop(Looper.java:137)
02-02 19:04:34.145: E/ActivityThread(21488):    at android.app.ActivityThread.main(ActivityThread.java:5279)
02-02 19:04:34.145: E/ActivityThread(21488):    at java.lang.reflect.Method.invokeNative(Native Method)
02-02 19:04:34.145: E/ActivityThread(21488):    at java.lang.reflect.Method.invoke(Method.java:511)
02-02 19:04:34.145: E/ActivityThread(21488):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
02-02 19:04:34.145: E/ActivityThread(21488):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
02-02 19:04:34.145: E/ActivityThread(21488):    at dalvik.system.NativeStart.main(Native Method)
02-02 19:05:39.800: E/TestService(21488): Service Created..
02-02 19:05:39.800: E/TestService(21488): Service started..
02-02 19:05:44.795: E/ActivityThread(21488): Activity com.example.backgroundservice.MainActivity has leaked ServiceConnection com.example.backgroundservice.MainActivity$1@424cf1d8 that was originally bound here
02-02 19:05:44.795: E/ActivityThread(21488): android.app.ServiceConnectionLeaked: Activity com.example.backgroundservice.MainActivity has leaked ServiceConnection com.example.backgroundservice.MainActivity$1@424cf1d8 that was originally bound here
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.LoadedApk$ServiceDispatcher.<init>(LoadedApk.java:974)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.LoadedApk.getServiceDispatcher(LoadedApk.java:868)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.ContextImpl.bindService(ContextImpl.java:1762)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.ContextImpl.bindService(ContextImpl.java:1751)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.content.ContextWrapper.bindService(ContextWrapper.java:480)
02-02 19:05:44.795: E/ActivityThread(21488):    at com.example.backgroundservice.MainActivity.onCreate(MainActivity.java:26)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.Activity.performCreate(Activity.java:5276)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.ActivityThread.access$700(ActivityThread.java:150)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.os.Looper.loop(Looper.java:137)
02-02 19:05:44.795: E/ActivityThread(21488):    at android.app.ActivityThread.main(ActivityThread.java:5279)
02-02 19:05:44.795: E/ActivityThread(21488):    at java.lang.reflect.Method.invokeNative(Native Method)
02-02 19:05:44.795: E/ActivityThread(21488):    at java.lang.reflect.Method.invoke(Method.java:511)
02-02 19:05:44.795: E/ActivityThread(21488):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
02-02 19:05:44.795: E/ActivityThread(21488):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
02-02 19:05:44.795: E/ActivityThread(21488):    at dalvik.system.NativeStart.main(Native Method)

修改过的服务类

package com.example.backgroundservice;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;


public class MyService extends Service {

    String tag="TestService";

    @Override
    public void onCreate(){
        super.onCreate();
        Toast.makeText(this, "Service Created..", Toast.LENGTH_LONG).show();
        Log.e(tag, "Service Created..");
    }

    @SuppressWarnings("deprecation")
    @Override
    public void onStart(Intent intent, int startId){
        super.onStart(intent, startId);
        Log.e(tag, "Service started..");
    }

    @Override
    public void onDestroy(){
        super.onDestroy();
        Toast.makeText(this, "Service destroyed..", Toast.LENGTH_LONG).show();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }

     class LocalBinder extends Binder {
            MyService getService() {
                // Return this instance of LocalService so clients can call public methods
                return MyService.this;
            }
        }

}

修改后的主要活动类

package com.example.backgroundservice;

import com.example.backgroundservice.MyService.LocalBinder;

import android.os.Bundle;
import android.os.IBinder;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.widget.TextView;

public class MainActivity extends Activity {

    MyService mService;
    boolean mBound;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        TextView view = new TextView(this);
        view.setText("Service Test");
        Intent i = new Intent();
        i.setClassName("com.example.backgroundservice", "com.example.backgroundservice.MyService");
        bindService(i, mConnection, Context.BIND_AUTO_CREATE);
        this.startService(i);
        setContentView(view);
    }

    private ServiceConnection mConnection = new ServiceConnection() {

        @Override
        public void onServiceConnected(ComponentName className,
                IBinder service) {
            // We've bound to LocalService, cast the IBinder and get LocalService instance
            LocalBinder binder = (LocalBinder) service;
            mService = binder.getService();
            mBound = true;
        }

        @Override
        public void onServiceDisconnected(ComponentName arg0) {
            mBound = false;
        }
    };

}

Answer 1

基本上你拥有这一切，在这一行：

bindService（i，null，Context.BIND_AUTO_CREATE）;

conn参数不能为null：

http://developer.android.com/reference/android/content/Context.html#bindService%28android.content.Intent,%20android.content.ServiceConnection,%20int%29

conn在服务启动和停止时接收信息。这个必须是有效的ServiceConnection对象;它不能为空。

您可以在此处找到绑定服务的完整示例：

http://developer.android.com/guide/components/bound-services.html

Answer 2

类似文档说link do tocs

第二个参数不能为空ServiceConnection conn,“在服务启动和停止时接收信息。这必须是有效的ServiceConnection对象;它不能为空。”

Answer 3

Android服务可以采用两种形式：启动和绑定。启动服务是通过调用startService()方法启动的，通常用于执行单个操作。当然，他们也可能在后台无限期地运行。通过调用stopSelf()完成操作后，此类服务可能会自行停止。如果您想使用此类服务，请删除以下行以消除异常：bindService(i, null, Context.BIND_AUTO_CREATE);

请注意，API级别5中已弃用onStart()回调。您应该使用onStartCommand(Intent intent, int flags, int startId)代替。

IllegalArgumentException：运行后台服务时，connection为null

3 个答案: