Android微信右滑退出功能的实现代码

<!-- Base application theme. -->
 <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
  <!-- Customize your theme here. -->
  <item name="colorPrimary">@color/colorPrimary</item>
  <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
  <item name="colorAccent">@color/colorAccent</item>
 </style>
 <style name="CustomTheme" parent="AppTheme">
  <item name="android:windowIsTranslucent">true</item>
  <item name="android:windowBackground">@android:color/transparent</item>
 </style>
<activity android:name=".Main2Activity">
   <intent-filter>
    <action android:name="android.intent.action.MAIN" />
    <category android:name="android.intent.category.LAUNCHER" />
   </intent-filter>
  </activity>
  <activity
   android:name=".Main3Activity"
   android:theme="@style/CustomTheme" />

public class Main3Activity extends AppCompatActivity {
 /**
  * DecorView左边滑出间距占屏幕宽度PRESENT_TO_FINISH时表示用户需要退出当前Activity
  */
 private static final float PRESENT_TO_FINISH = 0.3f;
 /**
  * 用户距离左边MIN_EDGE_DISTANCE内拖动有效
  */
 private static final int MIN_EDGE_DISTANCE = 100;
 /**
  * 屏幕宽度
  */
 private static float mScreenW = -1;
 /**
  * 用户计算用户在屏幕滑动的距离
  */
 private float mStartX = 0;
 /**
  * 当前是否允许拖动
  */
 private boolean mIsScrollEnable = false;
 /**
  * 当前Activity的DecorView
  */
 private View mDecorView;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main3);
  // 初始化
  mDecorView = getWindow().getDecorView();
  if (mScreenW == -1) {
   DisplayMetrics metrics = new DisplayMetrics();
   getWindowManager().getDefaultDisplay()
     .getMetrics(metrics);
   mScreenW = metrics.widthPixels;
  }
 }
 @Override
 public boolean onTouchEvent(MotionEvent event) {
  if (event.getAction() == MotionEvent.ACTION_DOWN) {
   mStartX = event.getX();
   if (mStartX < MIN_EDGE_DISTANCE) {
    // 距离左边距离足够小，设置为可拖动状态
    mIsScrollEnable = true;
   }
  } else if (event.getAction() == MotionEvent.ACTION_MOVE && mIsScrollEnable) {
   // 滚动DecorView内容
   float dX = event.getX() - mStartX;
   mStartX = event.getX();
   mDecorView.scrollBy((int) -dX, 0);
   return true;
  } else if (event.getAction() == MotionEvent.ACTION_UP || event.getAction() == MotionEvent.ACTION_CANCEL) {
   // 触摸操作取消，重置
   mIsScrollEnable = false;
   // 根据当前滑动状态判断最终是滑到左边还是滑到右边（结束Activity）
   final int targetX = -mDecorView.getScrollX() / mScreenW > PRESENT_TO_FINISH ? (int) -mScreenW : 0;
   ValueAnimator animator = ValueAnimator.ofInt(mDecorView.getScrollX(), targetX);
   animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
     mDecorView.scrollTo((Integer) animation.getAnimatedValue(), 0);
    }
   });
   animator.addListener(new Animator.AnimatorListener() {
    @Override
    public void onAnimationStart(Animator animation) {
    }
    @Override
    public void onAnimationEnd(Animator animation) {
     if (targetX == -mScreenW) {
      finish();
     }
    }
    @Override
    public void onAnimationCancel(Animator animation) {
    }
    @Override
    public void onAnimationRepeat(Animator animation) {
    }
   });
   animator.start();
  }
  return super.onTouchEvent(event);
 }
}