基于Android DataBinding的InverseBindingMethod改进SeekBar双向绑定（正向/反向）数据绑定

向右看齐 2023-10-17 15:37 83阅读 0赞

**基于Android DataBinding的InverseBindingMethod改进SeekBar双向绑定（正向/反向）数据绑定**

在前文《使用Android BindingAdapter与InverseBindingAdapter实现SeekBar双向（正向/反向）数据绑定》（链接：http://blog.csdn.net/zhangphil/article/details/77839555 ）基础上，用InverseBindingMethod改进双向绑定实现方案。  
  
老规矩，先建立数据模型，PhilProgress.java：

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

重写SeekBar，PhilSeekBar.java：

package zhangphil.test;
    
    import android.content.Context;
    import android.databinding.InverseBindingListener;
    import android.databinding.InverseBindingMethod;
    import android.databinding.InverseBindingMethods;
    import android.util.AttributeSet;
    import android.util.Log;
    import android.widget.SeekBar;
    
    /**
     * Created by Phil on 2017/9/4.
     */
    
    @InverseBindingMethods({@InverseBindingMethod(type = PhilSeekBar.class, attribute = "progress", event = "progressAttrChanged")})
    
    public class PhilSeekBar extends SeekBar {
        private String TAG = "调试输出";
    
        private int progress = 0;
        private 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) {
                    progress = i;
    
                    //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) {
    
                }
            });
        }
    
        public void setProgress(int p) {
            Log.d(TAG, "setProgress:" + p);
    
            if (progress != p) {
                progress = p;
    
                //这一句代码可以解决初始化阶段进度条显示的值正确，但没有及时更新UI的问题。
                //super.setProgress(progress);
            }
        }
    
        public int getProgress() {
            Log.d(TAG, "getProgress:" + progress);
    
            return progress;
        }
    
        public void setProgressAttrChanged(InverseBindingListener inverseBindingListener) {
            if (inverseBindingListener != null) {
                mInverseBindingListener = inverseBindingListener;
            }
        }
    }

写布局activity\_main.xml使用PhilSeekBar:

<?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.PhilProgress" />
        </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:progress="@={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>

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);
    
            final PhilProgress progress = new PhilProgress();
            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);
        }
    }

代码初始运行结果：  
![Center][]  
注意到虽然进度条显示到了21，但是却没有彩色着色，在PhilSeekBar的setProgress方法里面，启用super.setProgress可以解决这个问题。  
  
  
手指拖动后的结果显示：  
![Center 1][]

[Center]: https://img-blog.csdn.net/20170906140112818?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhbmdwaGls/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 1]: https://img-blog.csdn.net/20170906140230289?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhbmdwaGls/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center