错误：
java.lang.IllegalStateException: Activity has been destroyed
at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1555)
at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:696)
at android.support.v4.app.BackStackRecord.commitAllowingStateLoss(BackStackRecord.java:667)
at com.bumptech.glide.manager.RequestManagerRetriever.getSupportRequestManagerFragment(RequestManagerRetriever.java:187)
at com.bumptech.glide.manager.RequestManagerRetriever.supportFragmentGet(RequestManagerRetriever.java:195)
at com.bumptech.glide.manager.RequestManagerRetriever.get(RequestManagerRetriever.java:104)
at com.bumptech.glide.Glide.with(Glide.java:644)
at com.meinong.activity.PickPhotoPreviewActivity.setRootView(PickPhotoPreviewActivity.java:51)
at org.mn.frame.MNActivity.onCreate(MNActivity.java:141)
at android.app.Activity.performCreate(Activity.java:6875)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2659)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2767)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1514)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:163)
at android.app.ActivityThread.main(ActivityThread.java:6221)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.meinong.test/com.meinong.activity.PickPhotoPreviewActivity}: java.lang.IllegalStateException: Activity has been destroyed
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2706)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2767)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1514)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:163)
at android.app.ActivityThread.main(ActivityThread.java:6221)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
网上所有跟这个错误有关的都是有fragment的activity但是我的act没有fragment，所以不知道原因出在哪
一步步看源码找到异常抛出的位置在android.support.v4.app.FragmentManagerImpl的enqueueAction（）方法：
public void enqueueAction(Runnable action,boolean allowStateLoss) {
if (!allowStateLoss) {
checkStateLoss();
}
synchronized (this) {
if (mDestroyed ||mHost ==null) {
throw new IllegalStateException("Activity has been destroyed");
}
if (mPendingActions ==null) {
mPendingActions =new ArrayList();
}
mPendingActions.add(action);
if (mPendingActions.size() ==1) {
mHost.getHandler().removeCallbacks(mExecCommit);
mHost.getHandler().post(mExecCommit);
}
}
}
mDestroyed等于true或者mHost ==null。
继续追查mHost的赋值只有一个地方，FragmentManagerImpl的attachController（）方法：
public void attachController(FragmentHostCallback host,
FragmentContainer container, Fragment parent) {
if (mHost !=null)throw new IllegalStateException("Already attached");
mHost = host;
mContainer = container;
mParent = parent;
}
mHost = host; --而attachController的调用在FragmentController的attachHost（）方法：
public void attachHost(Fragment parent) {
mHost.mFragmentManager.attachController(
mHost,mHost /*container*/, parent);
}
而 的调用在FragmentActivity（）的oncreate中 第一行。
但是我发现继承FragmentActivity的类调用Glide.with方法竟然在super.onCreate(savedInstanceState);之前。。。
显然Glide.with调用时mHost还没有赋值，所以抛了异常IllegalStateException。。。
继承的activity，super.onCreate(savedInstanceState)一定要最先调用，切记切记！！！！！
