使用Android BindingAdapter与InverseBindingAdapter实现SeekBar双向（正向/反向）数据绑定

小鱼儿 2023-10-17 15:36 100阅读 0赞

**使用Android BindingAdapter与InverseBindingAdapter实现SeekBar双向（正向/反向）数据绑定**

在我之前写的系列文章中，继续深化Android数据绑定技术的使用。  
结合常用的SeekBar，实现用Android DataBinding数据绑定技术，设置从数据模型的值修改SeekBar的进度，以及实现常见的SeekBar拖动时候的进度回写到数据model中。也就是说，当用户手动拖动SeekBar这一View时候，View产生的结果，回写到我们建立的model中。

先任意建立一个数据模型Progress.java：

package zhangphil.test;
    
    import android.databinding.BaseObservable;
    import android.databinding.ObservableInt;
    
    /**
     * Created by Phil on 2017/9/4.
     */
    
    public class Progress extends BaseObservable {
        public final ObservableInt porgress = new ObservableInt();
    }

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>
    
            <variable
                name="progress"
                type="zhangphil.test.Progress" />
        </data>
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">
    
            <zhangphil.test.PhilSeekBar
                style="?android:attr/progressBarStyleHorizontal"
                android:layout_width="match_parent"
                android:layout_height="30dp"
                app:philprogress="@={progress.porgress}" />
    
            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:text="@{String.valueOf(progress.porgress)}"
                android:textColor="@android:color/holo_blue_light"
                android:textSize="50dp" />
    
        </LinearLayout>
    </layout>

关键的PhilSeekBar.java：

package zhangphil.test;
    
    import android.content.Context;
    import android.databinding.BindingAdapter;
    import android.databinding.InverseBindingAdapter;
    import android.databinding.InverseBindingListener;
    import android.util.AttributeSet;
    import android.util.Log;
    import android.widget.SeekBar;
    
    /**
     * Created by Phil on 2017/9/4.
     */
    
    public class PhilSeekBar extends SeekBar {
        private static InverseBindingListener mInverseBindingListener;
    
        public PhilSeekBar(Context context, AttributeSet attrs) {
            super(context, attrs);
    
            this.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
    
                @Override
                public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
                    //触发反向数据的传递
                    if (mInverseBindingListener != null) {
                        mInverseBindingListener.onChange();
                    }
                }
    
                @Override
                public void onStartTrackingTouch(SeekBar seekBar) {
    
                }
    
                @Override
                public void onStopTrackingTouch(SeekBar seekBar) {
    
                }
            });
        }
    
        @BindingAdapter(value = "philprogress", requireAll = false)
        public static void setPhilProgress(PhilSeekBar seekBar, int progress) {
            if (getPhilProgress(seekBar) != progress) {
                seekBar.setProgress(progress);
            }
        }
    
        @InverseBindingAdapter(attribute = "philprogress", event = "philprogressAttrChanged")
        public static int getPhilProgress(PhilSeekBar seekBar) {
            return seekBar.getProgress();
        }
    
        @BindingAdapter(value = {"philprogressAttrChanged"}, requireAll = false)
        public static void setPhilProgressAttrChanged(PhilSeekBar seekBar, InverseBindingListener inverseBindingListener) {
            if (inverseBindingListener == null) {
                Log.e("错误！", "InverseBindingListener为空!");
            } else {
                mInverseBindingListener = inverseBindingListener;
            }
        }
    }

测试的MainActivity.java：

package zhangphil.test;
    
    import android.app.Activity;
    import android.databinding.DataBindingUtil;
    import android.os.Bundle;
    
    import zhangphil.test.databinding.ActivityMainBinding;
    
    public class MainActivity extends Activity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
    
            ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
    
            Progress progress = new Progress();
            binding.setProgress(progress);
    
            //设置一个初始值作为演示 数据 -> View
            //这是最常见的进度设置。
            progress.porgress.set(21);
        }
    }

代码运行结果，初始化：

![Center][]

当手指拖动SeekBar时候，进度值回写到Progress的progress中，也再TextView中得到反应：

![Center 1][]

[Center]: https://img-blog.csdn.net/20170904171527793?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhbmdwaGls/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 1]: https://img-blog.csdn.net/20170904171622473?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhbmdwaGls/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center