Android PendingIntent和Intent的区别_

以前在学习AlarmManager里面会遇到PendingIntent，相信大家都知道Intent是你的意图，比如你想启动一个Activity,就会通过 Intent来描述启动这个Activity的某些特点，让系统找到这个Activity来启动，而不是启动别的 Activity.StartActivity(intent)就会立即启动这个Activity.而PendingIntent呢?Penging中文意思就是：待定，将来发生或来临。PendingIntent的就的意思就是不是像Intent那样立即发生，而是在合适的时候才会去触发对应的 Intent.有人说这个intent不是你的ap来触发而是交给别的ap来触发。你可以看以下的code来理解：

这是在PackageInstaller的代码

java代码：
private class ClearCacheReceiver extends BroadcastReceiver {
public static final String INTENT_CLEAR_CACHE ="com.android.packageinstaller.CLEAR_CACHE";

@Override
public void onReceive(Context context, Intent intent) {
Message msg = mHandler.obtainMessage(FREE_SPACE);
msg.arg1 = (getResultCode() ==1) ? SUCCEEDED : FAILED;
mHandler.sendMessage(msg);
}
}

java代码：
private void checkOutOfSpace(long size) {

if(localLOGV) Log.i(TAG, "Checking for "+size+" number of bytes");
if (mClearCacheReceiver == null) {
mClearCacheReceiver = new ClearCacheReceiver();
}

registerReceiver(mClearCacheReceiver,new IntentFilter(ClearCacheReceiver.INTENT_CLEAR_CACHE));

PendingIntent pi = PendingIntent.getBroadcast(this,0, new Intent(ClearCacheReceiver.INTENT_CLEAR_CACHE), 0);

mPm.freeStorage(size, pi.getIntentSender());
}

　以下是在PackageManagerService的：

java代码：
public void freeStorageAndNotify(final long freeStorageSize, final IPackageDataObserver observer) {
mContext.enforceCallingOrSelfPermission(

android.Manifest.permission.CLEAR_APP_CACHE, null);
// Queue up an async operation since clearing cache may take a little while.
mHandler.post(new Runnable() {

public void run() {
mHandler.removeCallbacks(this);
int retCode = -1;
if (mInstaller != null) {

retCode = mInstaller.freeCache(freeStorageSize);

if (retCode < 0) {
Slog.w(TAG, "Couldn't clear application caches");
}
} //end if mInstaller

if (observer != null) {
try {
observer.onRemoveCompleted(null, (retCode >= 0));
} catch (RemoteException e) {
Slog.w(TAG, "RemoveException when invoking call back");
}

}
}
});
}

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Android PendingIntent和Intent的区别