Android 滑动拦截实例代码解析

 package demo.hq.com.fby;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.LinearLayout;
/**
 * Created by huqing on 2016/12/7.
 * 思路：
 * 分内外部拦截
 * 在父布局中，onInterceptTouchEvent先判断是否拦截滑动，true 拦截 直接进入父布局的onTouch方法 ；false 进入子布局的onTouch方法
 */
public class MyParentView extends LinearLayout
{
  /**
   * 每向下Move移动的距离
   */
  private int mMove;
  /**
   * 落下点的位置
   */
  private int yDown;
  /**
   * 移动点的位置
   */
  private int yMove;
  /**
   * 一共向下挪动的距离
   */
  private int downDistance = 0;
  public MyParentView(Context context, AttributeSet attrs)
  {
    super(context, attrs);
  }
  boolean intercept = false;
  /**
   * 外部拦截，
   * 如果是向下滑动 则为true,交给该控件处理，向上false就交给子控件处理吧
   * 所以向上的事件 子控件都能获取到的
   *
   * @param ev
   * @return
   */
  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev)
  {
    switch (ev.getAction())
    {
      case MotionEvent.ACTION_DOWN:
        yDown =(int) ev.getY();
        break;
      case MotionEvent.ACTION_MOVE:
        yMove = (int) ev.getY();
        if (yMove > yDown)
        {
          intercept = true;
          Log.d("hqq", "拦截~~~~~~~~~~~~~~~~~~");
        }
        else if (yMove < yDown)
        {
          intercept = false;
          Log.d("hqq", "不拦截~~~~~~~~~~~~~~~~~~");
        }
        break;
      case MotionEvent.ACTION_UP:
        break;
    }
    //true 拦截，进入该控件的onTouchEvent方法 false：进入子控件的OnTouchEvent
    boolean returnInterCept = intercept;
    intercept = false;
    return returnInterCept;
  }
  @Override
  public boolean onTouchEvent(MotionEvent event)
  {
    Log.e("hq", "father onTouch");
    int y = (int) event.getY();
    switch (event.getAction())
    {
      case MotionEvent.ACTION_DOWN:
        yDown = y;
        break;
      case MotionEvent.ACTION_MOVE:
        if (downDistance>=250){
        }else {
          yMove = y;
          if (yMove - yDown > 0)
          {
            mMove = yMove - yDown;
            downDistance += mMove;
            if (downDistance>=250){
              layout(getLeft(),downDistance, getRight(), getHeight() + downDistance);
            }else {
              layout(getLeft(), getTop() + mMove, getRight(), getBottom() + mMove);
            }
          }
        }
        break;
      case MotionEvent.ACTION_UP:
        layout(getLeft(), getTop() - downDistance, getRight(), getBottom() - downDistance);
        downDistance = 0;
        break;
    }
    return true;//    return super.onTouchEvent(event);
  }
}

package demo.hq.com.fby;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.ScrollView;
/**
 * Created by huqing on 2016/12/7.
 */
public class MyScrollView extends ScrollView
{
  public MyScrollView(Context context, AttributeSet attrs)
  {
    super(context, attrs);
  }
  @Override
  public boolean onTouchEvent(MotionEvent ev)
  {
    Log.e("hq","child onTouch----------------");
    switch (ev.getAction()){
      case MotionEvent.ACTION_DOWN:
        getParent().requestDisallowInterceptTouchEvent(true);
        break;
      case MotionEvent.ACTION_MOVE:
        if (getScrollY()==0){//ScrollView没有滑动时 ，即滑动高度没变化的话就允许父控件拦截
          getParent().requestDisallowInterceptTouchEvent(false);
        }else {//禁止拦截
          getParent().requestDisallowInterceptTouchEvent(true);
        }
        break;
    }
    return super.onTouchEvent(ev);
  }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
  android:id="@+id/activity_main"
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@drawable/bg"
  tools:context="demo.hq.com.fby.MainActivity">
  <demo.hq.com.fby.MyParentView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#ffffff"
    android:orientation="vertical">
    <TextView
      android:layout_width="wrap_content"
      android:layout_height="100dp"
      android:text=" World!"/>
    <TextView
      android:layout_width="wrap_content"
      android:layout_height="100dp"
      android:text=" World!"/>
    <demo.hq.com.fby.MyScrollView android:layout_width="match_parent"
                   android:layout_height="wrap_content">
      <LinearLayout android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:orientation="vertical">
        <TextView
          android:layout_width="wrap_content"
          android:layout_height="200dp"
          android:text="Hello World!"/>
        <TextView
          android:layout_width="wrap_content"
          android:layout_height="200dp"
          android:text="Hello World!"/>
      </LinearLayout>
    </demo.hq.com.fby.MyScrollView>
  </demo.hq.com.fby.MyParentView>
</RelativeLayout>