android - 配置更改后 Fragment.getArguments() 是否返回传递的参数？

Question

对不起我的英语

在配置更改期间，我是否应该保存和恢复参数(由getArguments()返回)outState\savedInstanceState 吗？

或者 getArguments() 即使在配置更改后也总是返回传递的参数？

Answer 1

简答

我只能回答否。

---

完整答案

您不必保存您的参数，它会自动完成。

这就是为什么:(也许我错了，但源代码是这样说的:)

在 android 支持库 v4 中

android-sdk/extras/android/support/v4/src/java/android/support/v4/app/Fragment.java

你有方法:

public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(mClassName);
    dest.writeInt(mIndex);
    dest.writeInt(mFromLayout ? 1 : 0);
    dest.writeInt(mFragmentId);
    dest.writeInt(mContainerId);
    dest.writeString(mTag);
    dest.writeInt(mRetainInstance ? 1 : 0);
    dest.writeInt(mDetached ? 1 : 0);
    dest.writeBundle(mArguments);//<---------------------------- Look here
    dest.writeBundle(mSavedFragmentState);
}

mArgument 是:

/**
 * Supply the construction arguments for this fragment.  This can only
 * be called before the fragment has been attached to its activity; that
 * is, you should call it immediately after constructing the fragment.  The
 * arguments supplied here will be retained across fragment destroy and
 * creation.
 */
public void setArguments(Bundle args) {
    if (mIndex >= 0) {
        throw new IllegalStateException("Fragment already active");
    }
    mArguments = args;
}

在

/**
* State information that has been retrieved from a fragment instance
* through {@link FragmentManager#saveFragmentInstanceState(Fragment)
* FragmentManager.saveFragmentInstanceState}.
*/
public static class SavedState implements Parcelable {
    final Bundle mState;

    SavedState(Bundle state) {
        mState = state;
    }

    SavedState(Parcel in, ClassLoader loader) {
        mState = in.readBundle();
        if (loader != null && mState != null) {
            mState.setClassLoader(loader);
        }
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeBundle(mState);
    }

    public static final Parcelable.Creator<SavedState> CREATOR
            = new Parcelable.Creator<SavedState>() {
        public SavedState createFromParcel(Parcel in) {
            return new SavedState(in, null);
        }

        public SavedState[] newArray(int size) {
            return new SavedState[size];
        }
    };
}

它被执行了。如评论中所述，您可以阅读 this is used :)。我还检查了代码，是的，它已保存。

在 FragmentManager.java 中

@Override
public Fragment.SavedState saveFragmentInstanceState(Fragment fragment) {
    if (fragment.mIndex < 0) {
        throwException( new IllegalStateException("Fragment " + fragment
                + " is not currently in the FragmentManager"));
    }
    if (fragment.mState > Fragment.INITIALIZING) {
        Bundle result = saveFragmentBasicState(fragment);
        return result != null ? new Fragment.SavedState(result) : null;
    }
    return null;
}

此外，我已经在 android 上测试了几次，它看起来仍然可以正常工作:)