我的Android進階之旅------Android 5.0中出現警告的解決方法： Service Intent must be explicit:

1.錯誤描述

今天在Android4.4 的小米4手機上運行我的程序的時候沒有報錯，而在Android 5.1的華為P7上運行我的程序的時候報了以下的錯誤，錯誤提示如下：

E/AndroidRuntime(12500): FATAL EXCEPTION: main
E/AndroidRuntime(12500): Process: com.xtc.watch, PID: 12500
E/AndroidRuntime(12500): java.lang.IllegalArgumentException: Service Intent must be explicit: Intent { act=com.xtc.kuwo.watch.MUSIC_PLAY_SERVICE (has extras) }
E/AndroidRuntime(12500):        at android.app.ContextImpl.validateServiceIntent(ContextImpl.java:1847)
E/AndroidRuntime(12500):        at android.app.ContextImpl.startServiceCommon(ContextImpl.java:1876)
E/AndroidRuntime(12500):        at android.app.ContextImpl.startService(ContextImpl.java:1860)
E/AndroidRuntime(12500):        at android.content.ContextWrapper.startService(ContextWrapper.java:516)
E/AndroidRuntime(12500):        at com.xtc.watch.kuwo.activity.WatchMusicPlay.pauseMusic(WatchMusicPlay.java:314)
E/AndroidRuntime(12500):        at com.xtc.watch.kuwo.activity.WatchMusicPlay.access$600(WatchMusicPlay.java:32)
E/AndroidRuntime(12500):        at com.xtc.watch.kuwo.activity.WatchMusicPlay$3.onClick(WatchMusicPlay.java:220)
E/AndroidRuntime(12500):        at android.view.View.performClick(View.java:4790)
E/AndroidRuntime(12500):        at android.view.View$PerformClick.run(View.java:19933)
E/AndroidRuntime(12500):        at android.os.Handler.handleCallback(Handler.java:739)
E/AndroidRuntime(12500):        at android.os.Handler.dispatchMessage(Handler.java:95)
E/AndroidRuntime(12500):        at android.os.Looper.loop(Looper.java:135)
E/AndroidRuntime(12500):        at android.app.ActivityThread.main(ActivityThread.java:5569)
E/AndroidRuntime(12500):        at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(12500):        at java.lang.reflect.Method.invoke(Method.java:372)
E/AndroidRuntime(12500):        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:931)
E/AndroidRuntime(12500):        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:726)

而我啟動Service的Intent代碼如下所示：

        Intent intent = new Intent();
        intent.setAction(MUSIC_PLAY_SERVICE);
        intent.putExtra("MSG", Constants.PlayerMsg.PAUSE_MSG);  //暫停播放音樂
        intent.putExtra("musicURL", musicURL);  //歌曲URL
        startService(intent);

2.錯誤原因

有些時候我們使用Service的時需要采用隱私啟動的方式，但是Android 5.0一出來後，其中有個特性就是Service Intent must be explitict，也就是說從Android Lollipop版本（Android 5.0）開始，service服務必須采用顯示方式啟動。

而android源碼是這樣寫的（源碼位置：sdk/sources/android-21/android/app/ContextImpl.java）：

startService(Intent service)方法

startService(Intent service)方法代碼如下

 @Override
    public ComponentName startService(Intent service) {
        warnIfCallingFromSystemProcess();
        return startServiceCommon(service, mUser);
    }

startServiceCommon(Intent service, UserHandle user)方法

上面的startService(Intent service)方法調用的是startServiceCommon(Intent service, UserHandle user)，代碼如下所示：

 private ComponentName startServiceCommon(Intent service, UserHandle user) {
        try {
            validateServiceIntent(service);
            service.prepareToLeaveProcess();
            ComponentName cn = ActivityManagerNative.getDefault().startService(
                mMainThread.getApplicationThread(), service,
                service.resolveTypeIfNeeded(getContentResolver()), user.getIdentifier());
            if (cn != null) {
                if (cn.getPackageName().equals("!")) {
                    throw new SecurityException(
                            "Not allowed to start service " + service
                            + " without permission " + cn.getClassName());
                } else if (cn.getPackageName().equals("!!")) {
                    throw new SecurityException(
                            "Unable to start service " + service
                            + ": " + cn.getClassName());
                }
            }
            return cn;
        } catch (RemoteException e) {
            return null;
        }
    }

validateServiceIntent(Intent service)方法

上面的startServiceCommon(Intent service, UserHandle user)方法中調用的validateServiceIntent(Intent service)方法代碼如下所示：

 private void validateServiceIntent(Intent service) {
        if (service.getComponent() == null && service.getPackage() == null) {
            if (getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.LOLLIPOP) {
                IllegalArgumentException ex = new IllegalArgumentException(
                        "Service Intent must be explicit: " + service);
                throw ex;
            } else {
                Log.w(TAG, "Implicit intents with startService are not safe: " + service
                        + " " + Debug.getCallers(2, 3));
            }
        }
    }

可以看得出來，就是在validateServiceIntent(Intent service)方法中判斷如果大於Build.VERSION_CODES.LOLLIPOP版本的話，並且啟動Service的Intent如果沒有設置Component和Package的話就會跑出異常java.lang.IllegalArgumentException: Service Intent must be explicit:

3.解決方法

設置要啟動Service的Intent的Action和packageName

        Intent intent = new Intent();
        intent.setAction(MUSIC_PLAY_SERVICE);
        intent.putExtra("MSG", Constants.PlayerMsg.PAUSE_MSG);  //暫停播放音樂
        intent.putExtra("musicURL", musicURL);  //歌曲URL
        startService(intent);

改為：

        Intent intent = new Intent();
        intent.setAction(MUSIC_PLAY_SERVICE);
        //不加這句話的話 android 5.0以上會報：Service Intent must be explitict
        intent.setPackage(getPackageName());
        intent.putExtra("MSG", Constants.PlayerMsg.PAUSE_MSG);  //暫停播放音樂
        intent.putExtra("musicURL", musicURL);  //歌曲URL
        startService(intent);

以上代碼就是加了一行<喎?/kf/ware/vc/" target="_blank" class="keylink">vcD4NCjxwcmUgY2xhc3M9"brush:java;"> //不加這句話的話 android 5.0以上會報：Service Intent must be explitict intent.setPackage(getPackageName());

此方式是google官方推薦使用的解決方法。

網站的截圖，如下所示：