public abstract @interface InverseBindingAdapter
implements Annotation
| android.databinding.InverseBindingAdapter |
InverseBindingAdapter与用于在设置从视图收集的值时检索视图值的方法相关联。 这类似于BindingAdapter s:
@InverseBindingAdapter(attribute = "android:text", event = "android:textAttrChanged")
public static String captureTextValue(TextView view, CharSequence originalValue) {
CharSequence newValue = view.getText();
CharSequence oldValue = value.get();
if (oldValue == null) {
value.set(newValue);
} else if (!contentEquals(newValue, oldValue)) {
value.set(newValue);
}
}
事件的默认值是带有“AttrChanged”后缀的属性名称。 在上面的例子中,即使没有提供,默认值也会是android:textAttrChanged 。
事件属性用于通知数据绑定系统该值已更改。 开发人员通常会创建一个BindingAdapter来分配事件。 例如:
@BindingAdapter(value = {"android:beforeTextChanged", "android:onTextChanged",
"android:afterTextChanged", "android:textAttrChanged"},
requireAll = false)
public static void setTextWatcher(TextView view, final BeforeTextChanged before,
final OnTextChanged on, final AfterTextChanged after,
final InverseBindingListener textAttrChanged) {
TextWatcher newValue = new TextWatcher() {
...
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (on != null) {
on.onTextChanged(s, start, before, count);
}
if (textAttrChanged != null) {
textAttrChanged.onChange();
}
}
}
TextWatcher oldValue = ListenerUtil.trackListener(view, newValue, R.id.textWatcher);
if (oldValue != null) {
view.removeTextChangedListener(oldValue);
}
view.addTextChangedListener(newValue);
}
与 BindingAdapter一样,InverseBindingAdapter方法也可能需要 DataBindingComponent作为第一个参数,并且可能是一个实例方法,其实例从 DataBindingComponent检索。
继承方法(Inherited methods) |
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java.lang.annotation.Annotation
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