我有一个自定义 View ，假设这是它的代码:

public class CustomView extends View {

    boolean visible;
    boolean enabled;

    public CustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);

        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomView, 0, 0);
        try {
            visible = a.getBoolean(R.styleable.CustomView_visible, true);
            enabled = a.getBoolean(R.styleable.CustomView_enabled, true);
        } finally {
            a.recycle();
        }

        // Apply XML attributes here
    }

    @Override
    public Parcelable onSaveInstanceState() {
        // Save instance state
        Bundle bundle = new Bundle();
        bundle.putParcelable("superState", super.onSaveInstanceState());
        bundle.putBoolean("visible", visible);
        bundle.putBoolean("enabled", enabled);

        return bundle;
    }

    @Override
    public void onRestoreInstanceState(Parcelable state) {
        // Restore instance state
        // This is called after constructor
        if (state instanceof Bundle) {
            Bundle bundle = (Bundle) state;
            visible = bundle.getBoolean("visible");
            enabled = bundle.getBoolean("enabled");

            state = bundle.getParcelable("superState");
        }
        super.onRestoreInstanceState(state);
    }
}

非常简单。我的自定义 View 从 XML 中读取属性并应用它们。这些属性在配置更改时保存和恢复。

但是如果我有两个不同的布局，例如两个不同的方向:

[layout-port/view.xml]
<CustomView
    custom:visible="true"
    custom:enabled="true"

[layout-land/view.xml]
<CustomView
    custom:visible="false"
    custom:enabled="false"

我的问题是，当更改设备方向时， View 状态保存为可见和启用，但现在 XML 布局状态 View 不应该有。构造函数在 onRestoreInstanceState 之前被调用，XML 属性被保存的状态覆盖。我不希望这样，XML 优先于保存的状态。

我做错了什么？解决此问题的最佳方法是什么？

最佳答案

在您的情况下，您必须将当前方向与其他属性一起存储在 Parcelable 中，并且仅在恢复的方向等于当前方向的情况下应用那些恢复的属性(即 Activity 被破坏并且由操作系统恢复)。在您的情况下，我将使用 android:tag 来定义当前方向，如下所示:

[layout-port/view.xml]
<CustomView
    android:tag="port"
    custom:visible="true"
    custom:enabled="true"

[layout-land/view.xml]
<CustomView
    android:tag="land"
    custom:visible="false"
    custom:enabled="false"

然后您的自定义 View 类将如下所示:

public class ScheduleView extends View {

    String orientation;
    boolean visible;
    boolean enabled;

    public ScheduleView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);

        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomView, 0, 0);
        try {
            visible = a.getBoolean(R.styleable.CustomView_visible, true);
            enabled = a.getBoolean(R.styleable.CustomView_enabled, true);
        } finally {
            a.recycle();
        }

        orientation = (String) getTag();
    }

    @Override
    public Parcelable onSaveInstanceState() {
        // Save instance state
        Bundle bundle = new Bundle();
        bundle.putParcelable("superState", super.onSaveInstanceState());
        bundle.putBoolean("visible", visible);
        bundle.putBoolean("enabled", enabled);
        bundle.putString("orientation", orientation);

        return bundle;
    }

    @Override
    public void onRestoreInstanceState(Parcelable state) {
        // Restore instance state
        // This is called after constructor
        if (state instanceof Bundle) {
            Bundle bundle = (Bundle) state;

            String restoredOrientation = bundle.getString("orientation");
            if (restoredOrientation.equals(orientation)) {
                visible = bundle.getBoolean("visible");
                enabled = bundle.getBoolean("enabled");
            }

            state = bundle.getParcelable("superState");
        }
        super.onRestoreInstanceState(state);
    }
}

尚未正确测试，但应该可以。希望对您有所帮助。

关于android - 在应用 XML 属性之前恢复 View 状态，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43459464/