浅谈AndroidView滑动冲突的解决方法

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
  int x=(int)ev.getX();
  int y=(int)ev.getY();
  boolean intercept=false;
  switch (ev.getAction()){
    //按下事件不要拦截,否则后续事件都会给ViewGroup处理
    case MotionEvent.ACTION_DOWN:
      intercept=false;
      break;
    case MotionEvent.ACTION_MOVE:
      //如果是横向移动就进行拦截,否则不拦截
      int deltaX=x-mLastX;
      int deltaY=y-mLastY;
      if(父容器需要当前点击事件){
        intercept=true;
      }else {
        intercept=false;
      }
      break;
    case MotionEvent.ACTION_UP:
      intercept=false;
      break;
  }
  mLastX = x;
  mLastY = y;
  return intercept;
}

public class MainActivity extends Activity{

  private HorizontalScrollView mListContainer;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    initView();
  }

  private void initView() {
    LayoutInflater inflater = getLayoutInflater();
    mListCOntainer= (HorizontalScrollView) findViewById(R.id.container);
    final int screenWidth = MyUtils.getScreenMetrics(this).widthPixels;
    for (int i = 0; i <3; i++) {
      ViewGroup layout = (ViewGroup) inflater.inflate(
          R.layout.content_layout, mListContainer, false);
      layout.getLayoutParams().width = screenWidth;
      TextView textView = (TextView) layout.findViewById(R.id.title);
      textView.setText("page " + (i + 1));
      layout.setBackgroundColor(Color.rgb(255 / (i + 1), 255 / (i + 1), 0));
      createList(layout);
      mListContainer.addView(layout);
    }
  }

  private void createList(ViewGroup layout) {
    ListView listView = (ListView) layout.findViewById(R.id.list);
    ArrayList datas = new ArrayList<>();
    for (int i = 0; i <50; i++) {
      datas.add("name " + i);
    }

    ArrayAdapter adapter = new ArrayAdapter<>(this, R.layout.content_list_item, R.id.name, datas);
    listView.setAdapter(adapter);
  }
}

/**
 * 横向布局控件
 * 模拟经典滑动冲突
 * 我们此处使用ScrollView来模拟ViewPager,那么必须手动处理滑动冲突，否则内外两层只能有一层滑动，那就是滑动冲突。另外内部左右滑动，外部上下滑动也同样属于该类
 */
public class HorizontalScrollView extends ViewGroup {

  //记录上次滑动的坐标
  private int mLastX = 0;
  private int mLastY = 0;
  private WindowManager wm;
  //子View的个数
  private int mChildCount;
  private int mScreenWidth;
  //自定义控件横向宽度
  private int mMeasureWidth;
  //滑动加载下一个界面的阈值
  private int mCrital;
  //滑动辅助类
  private Scroller mScroller;
  //当前展示的子View的索引
  private int showViewIndex;

  public HorizontalScrollView(Context context){
    this(context,null);
  }

  public HorizontalScrollView(Context context, AttributeSet attributeSet){
    super(context,attributeSet);
    init(context);
  }

  /**
   * 初始化
   * @param context
   */
  public void init(Context context) {
    //读取屏幕相关的长宽
    wm = ((Activity)context).getWindowManager();
    mScreenWidth = wm.getDefaultDisplay().getWidth();
    mCrital=mScreenWidth/4;
    mScroller=new Scroller(context);
    showViewIndex=1;
  }

  /**
   * 重新事件拦截机制
   * 我们分析了view的事件分发，我们知道点击事件的分发顺序是 通过父布局分发，如果父布局没有拦截，即onInterceptTouchEvent返回false，
   * 才会传递给子View。所以我们就可以利用onInterceptTouchEvent()这个方法来进行事件的拦截。来看一下代码
   * 此处使用外部拦截法
   * @param ev
   * @return
   */
  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev) {
    int x=(int)ev.getX();
    int y=(int)ev.getY();
    boolean intercept=false;
    switch (ev.getAction()){
      //按下事件不要拦截,否则后续事件都会给ViewGroup处理
      case MotionEvent.ACTION_DOWN:
        intercept=false;
        if(!mScroller.isFinished()){
          mScroller.abortAnimation();
          intercept=true;
        }
        break;
      case MotionEvent.ACTION_MOVE:
        //如果是横向移动就进行拦截,否则不拦截
        int deltaX=x-mLastX;
        int deltaY=y-mLastY;
        if(Math.abs(deltaX)>Math.abs(deltaY)){
          intercept=true;
        }else {
          intercept=false;
        }
        break;
      case MotionEvent.ACTION_UP:
        intercept=false;
        break;
    }
    mLastX = x;
    mLastY = y;
    return intercept;
  }


  @Override
  public boolean onTouchEvent(MotionEvent event) {
    int x = (int) event.getX();
    int y = (int) event.getY();
    switch (event.getAction()) {
      case MotionEvent.ACTION_DOWN:
        if(!mScroller.isFinished()){
          mScroller.abortAnimation();
        }
        break;
      case MotionEvent.ACTION_MOVE:
        int deltaX = x - mLastX;
        /**
         * scrollX是指ViewGroup的左侧边框和当前内容左侧边框之间的距离
         */
        int scrollX=getScrollX();
        if(scrollX-deltaX>0
            && (scrollX-deltaX)<=(mMeasureWidth-mScreenWidth)) {
          scrollBy(-deltaX, 0);
        }
        break;
      case MotionEvent.ACTION_UP:
        scrollX=getScrollX();
        int dx;
        //计算滑动的差值,如果超过1/4就滑动到下一页
        int subScrollX=scrollX-((showViewIndex-1)*mScreenWidth);
        if(Math.abs(subScrollX)>=mCrital){
          boolean next=scrollX>(showViewIndex-1)*mScreenWidth;
          if(showViewIndex<3 && next) {
            showViewIndex++;
          }else {
            showViewIndex--;
          }
        }
        dx=(showViewIndex - 1) * mScreenWidth - scrollX;
        smoothScrollByDx(dx);
        break;
    }
    mLastX = x;
    mLastY = y;
    return true;
  }


  /**
   * 缓慢滚动到指定位置
   * @param dx
   */
  private void smoothScrollByDx(int dx) {
    //在1000毫秒内滑动dx距离，效果就是慢慢滑动
    mScroller.startScroll(getScrollX(), 0, dx, 0, 1000);
    invalidate();
  }

  @Override
  public void computeScroll() {
    if (mScroller.computeScrollOffset()) {
      scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
      postInvalidate();
    }
  }
}