Android官方DataBinding(十一):对于双向绑定之反向绑定的改进和简化
本文接附录十文章,对附录十文章的代码和逻辑进行改进和简化,使得代码更易于阅读和理解,进一步清晰化文章十的下拉刷新实现代码和逻辑。
package zhangphil.test; import android.databinding.BaseObservable; import android.databinding.ObservableBoolean; /** * Created by Phil on 2017/8/25. */ public class ViewModel extends BaseObservable { public final ObservableBoolean isRefreshing = new ObservableBoolean(); }
写布局activity_main.xml:
<?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"> <data> <import type="android.view.View" /> <variable name="model" type="zhangphil.test.ViewModel" /> </data> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <ProgressBar android:layout_width="100dp" android:layout_height="100dp" android:layout_gravity="center_horizontal" android:visibility="@{model.isRefreshing ? View.VISIBLE:View.GONE}" /> <TextView android:layout_width="match_parent" android:layout_height="50dp" android:background="@android:color/holo_red_light" android:gravity="center" android:text="加载中..." android:visibility="@{model.isRefreshing ? View.VISIBLE:View.GONE}" /> <zhangphil.test.PhilView android:id="@+id/philview" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@android:color/holo_blue_light" app:refreshing="@={model.isRefreshing}"> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> <TextView android:layout_width="match_parent" android:layout_height="150dp" android:gravity="center" android:text="z" /> <TextView android:layout_width="match_parent" android:layout_height="150dp" android:gravity="center" android:text="h" /> <TextView android:layout_width="match_parent" android:layout_height="150dp" android:gravity="center" android:text="a" /> <TextView android:layout_width="match_parent" android:layout_height="150dp" android:gravity="center" android:text="n" /> <TextView android:layout_width="match_parent" android:layout_height="150dp" android:gravity="center" android:text="g" /> </LinearLayout> </zhangphil.test.PhilView> </LinearLayout> </layout>
自定义的双向绑定PhilView.java:
package zhangphil.test; import android.content.Context; import android.databinding.BindingAdapter; import android.databinding.InverseBindingAdapter; import android.databinding.InverseBindingListener; import android.support.v4.widget.NestedScrollView; import android.util.AttributeSet; import android.util.Log; /** * Created by Phil on 2017/8/25. */ public class PhilView extends NestedScrollView { private static final String TAG = "调试"; private static boolean isRefreshing = false; public PhilView(Context context, AttributeSet attrs) { super(context, attrs); } @BindingAdapter(value = "refreshing", requireAll = false) public static void setRefreshing(PhilView view, boolean refreshing) { if (isRefreshing == refreshing) { //防止死循环 Log.d(TAG, "重复设置"); return; } else { Log.d(TAG, "setRefreshing " + refreshing); isRefreshing = refreshing; } } @InverseBindingAdapter(attribute = "refreshing", event = "refreshingAttrChanged") public static boolean getRefreshing(PhilView view) { return isRefreshing; } @BindingAdapter(value = {"refreshingAttrChanged"}, requireAll = false) public static void setRefreshingAttrChanged(PhilView view, final InverseBindingListener inverseBindingListener) { if (inverseBindingListener == null) { Log.e(TAG, "InverseBindingListener为空!"); } else { Log.d(TAG, "setRefreshingAttrChanged"); inverseBindingListener.onChange(); } } }
测试的MainActivity.java:
package zhangphil.test; import android.databinding.DataBindingUtil; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.GestureDetector; import android.view.MotionEvent; import android.view.View; import zhangphil.test.databinding.ActivityMainBinding; public class MainActivity extends AppCompatActivity { private final String TAG = "MainActivity调试"; private ViewModel mViewModel; private ActivityMainBinding binding; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); final GestureDetector mGestureDetector = createGestureDetector(); binding = DataBindingUtil.setContentView(this, R.layout.activity_main); mViewModel = new ViewModel(); binding.setModel(mViewModel); binding.philview.setOnTouchListener(new View.OnTouchListener() { @Override public boolean onTouch(View view, MotionEvent motionEvent) { mGestureDetector.onTouchEvent(motionEvent); return false; } }); } private GestureDetector createGestureDetector() { // mGestureDetector用于监测用户在手机屏幕上的上滑和下滑事件。 GestureDetector mGestureDetector = new GestureDetector(this, new GestureDetector.SimpleOnGestureListener() { @Override public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { //处于顶部且用户再下拉 if ((distanceY < 0) && (binding.philview.getScrollY() == 0)) { if (mViewModel.isRefreshing.get()) { Log.d(TAG, "加载中,请勿重复加载"); } else { Log.d(TAG, "开始下拉刷新..."); //执行下拉刷新/加载更多事务 loadMore(); } } return super.onScroll(e1, e2, distanceX, distanceY); } }); return mGestureDetector; } private void loadMore() { new Thread(new Runnable() { @Override public void run() { //通过设置布尔值改变View mViewModel.isRefreshing.set(true); try { //假设这里做了一个长时间的耗时操作 Thread.sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); } //通过设置布尔值改变View mViewModel.isRefreshing.set(false); } }).start(); } }
代码运行结果,下拉刷新:
附录:
1,《Android官方DataBinding简例(一)》链接:http://blog.csdn.net/zhangphil/article/details/77322530
2,《Android官方DataBinding(二):动态数据更新notifyPropertyChanged》链接:http://blog.csdn.net/zhangphil/article/details/77328688
3,《Android官方DataBinding(三):RecyclerView 使用ViewDataBinding更新数据》链接:http://blog.csdn.net/zhangphil/article/details/77367432
4,《Android官方DataBinding(四):BindingAdapter》链接:http://blog.csdn.net/zhangphil/article/details/77374211
5,《Android官方DataBinding(五):ObservableMap,ObservableArrayMap》链接:http://blog.csdn.net/zhangphil/article/details/77448933
6,《Android官方DataBinding(六): @= 操作符进行双向绑定》链接:http://blog.csdn.net/zhangphil/article/details/77454045
7,《Android官方DataBinding(七):BindingMethods与BindingMethod》链接:http://blog.csdn.net/zhangphil/article/details/77479843
8,《Android官方DataBinding(八):Lambda长表达式事件处理》链接:http://blog.csdn.net/zhangphil/article/details/77503013
9,《Android官方DataBinding(九):反向绑定,View变化结果回写进数据模型中》链接:http://blog.csdn.net/zhangphil/article/details/77649256
10,《Android官方DataBinding(十):双向绑定之基于InverseBindingAdapter的反向绑定》链接:http://blog.csdn.net/zhangphil/article/details/77767513