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

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"?>

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：

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：

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