android滑动冲突的解决方案

Android 中解决滑动的方案有2种：外部拦截法 和内部拦截法。
滑动冲突也存在2种场景: 横竖滑动冲突、同向滑动冲突。

所以我就写了4个例子来学习如何解决滑动冲突的，这四个例子分别为: 外部拦截法解决横竖冲突、外部拦截法解决同向冲突、内部拦截法解决横竖冲突、内部拦截法解决同向冲突。
先上效果图：

二、实战
1、外部拦截法，解决横竖冲突
思路是，重写父控件的onInterceptTouchEvent方法，然后根据具体的需求，来决定父控件是否拦截事件。如果拦截返回返回true，不拦截返回false。关于为什么返回true就代表拦截事件 。 如果父控件拦截了事件，则在父控件的onTouchEvent进行相应的事件处理。
我的这个例子，是一个横向滑动的ViewGroup里面包含了3个竖向滑动的ListView。下面我附上代码：
HorizontalEx.java

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 * Created by blueberry on 2016/6/20.

 *

 * 解决交错的滑动冲突

 *

 * 外部拦截法

 */

public class HorizontalEx extends ViewGroup {

 

    private static final String TAG = "HorizontalEx";

 

    private boolean isFirstTouch = true;

    private int childIndex;

    private int childCount;

    private int lastXIntercept, lastYIntercept, lastX, lastY;

 

    private Scroller mScroller;

    private VelocityTracker mVelocityTracker;

 

    public HorizontalEx(Context context) {

        super(context);

        init();

    }

 

    public HorizontalEx(Context context, AttributeSet attrs) {

        super(context, attrs);

        init();

    }

 

    public HorizontalEx(Context context, AttributeSet attrs, int defStyleAttr) {

        super(context, attrs, defStyleAttr);

        init();

    }

 

    private void init() {

        mScroller = new Scroller(getContext());

        mVelocityTracker = VelocityTracker.obtain();

    }

 

    @Override

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        int width = MeasureSpec.getSize(widthMeasureSpec);

        int height = MeasureSpec.getSize(heightMeasureSpec);

        int widthMode = MeasureSpec.getMode(widthMeasureSpec);

        int heightMode = MeasureSpec.getMode(heightMeasureSpec);

 

        childCount = getChildCount();

        measureChildren(widthMeasureSpec, heightMeasureSpec);

 

        if (childCount == 0) {

            setMeasuredDimension(0, 0);

        } else if (widthMode == MeasureSpec.AT_MOST && heightMode == MeasureSpec.AT_MOST) {

            width = childCount * getChildAt(0).getMeasuredWidth();

            height = getChildAt(0).getMeasuredHeight();

            setMeasuredDimension(width, height);

        } else if (widthMode == MeasureSpec.AT_MOST) {

            width = childCount * getChildAt(0).getMeasuredWidth();

            setMeasuredDimension(width, height);

        } else {

            height = getChildAt(0).getMeasuredHeight();

            setMeasuredDimension(width, height);

        }

    }

 

    @Override

    protected void onLayout(boolean changed, int l, int t, int r, int b) {

        int left = 0;

        for (int i = 0; i < getChildCount(); i++) {

            final View child = getChildAt(i);

            child.layout(left + l, t, r + left, b);

            left += child.getMeasuredWidth();

        }

    }

 

    /**

     * 拦截事件

     * @param ev

     * @return

     */

    @Override

    public boolean onInterceptTouchEvent(MotionEvent ev) {

        boolean intercepted = false;

        int x = (int) ev.getX();

        int y = (int) ev.getY();

 

        switch (ev.getAction()) {

            /*如果拦截了Down事件,则子类不会拿到这个事件序列*/

            case MotionEvent.ACTION_DOWN:

                lastXIntercept = x;

                lastYIntercept = y;

                intercepted = false;

                if (!mScroller.isFinished()) {

                    mScroller.abortAnimation();

                    intercepted = true;

                }

                break;

            case MotionEvent.ACTION_MOVE:

                final int deltaX = x - lastXIntercept;

                final int deltaY = y - lastYIntercept;

                /*根据条件判断是否拦截该事件*/

                if (Math.abs(deltaX) > Math.abs(deltaY)) {

                    intercepted = true;

                } else {

                    intercepted = false;

                }

                break;

            case MotionEvent.ACTION_UP:

                intercepted = false;

                break;

 

        }

        lastXIntercept = x;

        lastYIntercept = y;

        return intercepted;

    }

 

 

    @Override

    public boolean onTouchEvent(MotionEvent event) {

        int x = (int) event.getX();

        int y = (int) event.getY();

        mVelocityTracker.addMovement(event);

        ViewConfiguration configuration = ViewConfiguration.get(getContext());

        switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:

                if (!mScroller.isFinished()) {

                    mScroller.abortAnimation();

                }

                break;

            case MotionEvent.ACTION_MOVE:

                /*因为这里父控件拿不到Down事件，所以使用一个布尔值，

                    当事件第一次来到父控件时，对lastX,lastY赋值*/

                if (isFirstTouch) {

                    lastX = x;

                    lastY = y;

                    isFirstTouch = false;

                }

                final int deltaX = x - lastX;

                scrollBy(-deltaX, 0);

                break;

            case MotionEvent.ACTION_UP:

                int scrollX = getScrollX();

                final int childWidth = getChildAt(0).getWidth();

                mVelocityTracker.computeCurrentVelocity(1000, configuration.getScaledMaximumFlingVelocity());

                float xVelocity = mVelocityTracker.getXVelocity();

                if (Math.abs(xVelocity) > configuration.getScaledMinimumFlingVelocity()) {

                    childIndex = xVelocity < 0 ? childIndex + 1 : childIndex - 1;

                } else {

                    childIndex = (scrollX + childWidth / 2) / childWidth;

                }

                childIndex = Math.min(getChildCount() - 1, Math.max(childIndex, 0));

                smoothScrollBy(childIndex * childWidth - scrollX, 0);

                mVelocityTracker.clear();

                isFirstTouch = true;

                break;

        }

 

        lastX = x;

        lastY = y;

        return true;

    }

 

    void smoothScrollBy(int dx, int dy) {

        mScroller.startScroll(getScrollX(), getScrollY(), dx, dy, 500);

        invalidate();

    }

 

    @Override

    public void computeScroll() {

        if (mScroller.computeScrollOffset()) {

            scrollTo(mScroller.getCurrX(), mScroller.getCurrY());

            invalidate();

        }

    }

 

    @Override

    protected void onDetachedFromWindow() {

        super.onDetachedFromWindow();

        mVelocityTracker.recycle();

    }

}

调用代码：

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<code class="hljs lasso"> @Override

    public void showOutHVData(List<string> data1, List<string> data2, List<string> data3) {

        ListView listView1 = new ListView(getContext());

        ArrayAdapter<string> adapter1 = new ArrayAdapter<string>(getContext(), android.R.layout.simple_list_item_1, data1);

        listView1.setAdapter(adapter1);

 

        ListView listView2 = new ListView(getContext());

        ArrayAdapter<string> adapter2 = new ArrayAdapter<string>(getContext(), android.R.layout.simple_list_item_1, data2);

        listView2.setAdapter(adapter2);

 

        ListView listView3 = new ListView(getContext());

        ArrayAdapter<string> adapter3 = new ArrayAdapter<string>(getContext(), android.R.layout.simple_list_item_1, data3);

        listView3.setAdapter(adapter3);

 

        ViewGroup.LayoutParams params

                = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,

                ViewGroup.LayoutParams.MATCH_PARENT);

 

        mHorizontalEx.addView(listView1, params);

        mHorizontalEx.addView(listView2, params);

        mHorizontalEx.addView(listView3, params);

    }

其实外部拦截的主要思想都在于对onInterceptTouchEvent的重写。

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<code class="hljs java">@Override

    public boolean onInterceptTouchEvent(MotionEvent ev) {

        boolean intercepted = false;

        int x = (int) ev.getX();

        int y = (int) ev.getY();

 

        switch (ev.getAction()) {

            /*如果拦截了Down事件,则子类不会拿到这个事件序列*/

            case MotionEvent.ACTION_DOWN:

                lastXIntercept = x;

                lastYIntercept = y;

                intercepted = false;

                if (!mScroller.isFinished()) {

                    mScroller.abortAnimation();

                    intercepted = true;

                }

                break;

            case MotionEvent.ACTION_MOVE:

                final int deltaX = x - lastXIntercept;

                final int deltaY = y - lastYIntercept;

                /*根据条件判断是否拦截该事件*/

                if (Math.abs(deltaX) > Math.abs(deltaY)) {

                    intercepted = true;

                } else {

                    intercepted = false;

                }

                break;

            case MotionEvent.ACTION_UP:

                intercepted = false;

                break;

 

        }

        lastXIntercept = x;

        lastYIntercept = y;

        return intercepted;

    }</code>

这几乎是一个实现外部拦截事件的模板，这里一定不要在ACTION_DOWN 中返回 true,否则会让子VIew没有机会得到事件，因为如果在ACTION_DOWN的时候返回了 true,同一个事件序列ViewGroup的disPatchTouchEvent就不会在调用onInterceptTouchEvent方法了，如果不明白可以参考我的上一遍文章。
还有就是 在ACTION_UP中返回false，因为如果父控件拦截了ACTION_UP，那么子View将得不到UP事件，那么将会影响子View的 Onclick方法等。但这对父控件是没有影响的，因为如果是父控件子ACITON_MOVE中 就拦截了事件，他们UP事件必定也会交给它处理，因为有那么一条定律叫做：父控件一但拦截了事件，那么同一个事件序列的所有事件都将交给他处理。这条结论在我的上一篇文章中已经分析过。
最后就是在 ACTION_MOVE中根据需求决定是否拦截。

2、内部拦截法，解决横竖冲突
内部拦截主要依赖于父控件的 requestDisallowInterceptTouchEvent方法，关于这个方法我的上篇文章其实已经分析过。他设置父控件的一个标志（FLAG_DISALLOW_INTERCEPT）
这个标志可以决定父控件是否拦截事件，如果设置了这个标志则不拦截，如果没设这个标志，它就会调用父控件的onInterceptTouchEvent（）来询问父控件是否拦截。但这个标志对Down事件无效。
可以参考一下源码：
ViewGroup#dispatchTouchEvent

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<code class="hljs coffeescript">   // Handle an initial down.

            if (actionMasked == MotionEvent.ACTION_DOWN) {

                // Throw away all previous state when starting a new touch gesture.

                // The framework may have dropped the up or cancel event for the previous gesture

                // due to an app switch, ANR, or some other state change.

                cancelAndClearTouchTargets(ev);

                //清楚标志

                resetTouchState();

            }

 

            // Check for interception.

            final boolean intercepted;

            if (actionMasked == MotionEvent.ACTION_DOWN

                    || mFirstTouchTarget != null) {

                    //标志

                final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;

                if (!disallowIntercept) {

                    intercepted = onInterceptTouchEvent(ev);

                    ev.setAction(action); // restore action in case it was changed

                } else {

                    intercepted = false;

                }

            } else {

                // There are no touch targets and this action is not an initial down

                // so this view group continues to intercept touches.

                intercepted = true;

            }

</code>

那么我们如果想使用 内部拦截法拦截事件。
第一步：
a、我们要重写父控件的onInterceptTouchEvent，在ACTION_DOWN的时候返回false,负责的话子View调用requestDisallowInterceptTouchEvent也将无能为力。
b、还有就是其他事件的话都返回true,这样就把能否拦截事件的权利交给了子View。

第二步:
在子View的dispatchTouchEvent中 来决定是否让父控件拦截事件。
a. 先要在MotionEvent.ACTION_DOWN:的时候使用mHorizontalEx2.requestDisallowInterceptTouchEvent(true);，负责的话，下一个事件到来时，就交给父控件了。
b. 然后在MotionEvent.ACTION_MOVE: 根据业务逻辑决定是否调用mHorizontalEx2.requestDisallowInterceptTouchEvent(false);来决定父控件是否拦截事件。
上代码：
HorizontalEx2.java
 

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/**

 * Created by blueberry on 2016/6/20.

 * <p/>

 * 内部拦截

 * 和 ListViewEx配合使用

 */

public class HorizontalEx2 extends ViewGroup {

 

    private int lastX, lastY;

    private int childIndex;

    private Scroller mScroller;

    private VelocityTracker mVelocityTracker;

 

    public HorizontalEx2(Context context) {

        super(context);

        init();

    }

 

    public HorizontalEx2(Context context, AttributeSet attrs) {

        super(context, attrs);

        init();

    }

 

    public HorizontalEx2(Context context, AttributeSet attrs, int defStyleAttr) {

        super(context, attrs, defStyleAttr);

        init();

    }

 

    private void init() {

        mScroller = new Scroller(getContext());

        mVelocityTracker = VelocityTracker.obtain();

    }

 

    @Override

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        int width = MeasureSpec.getSize(widthMeasureSpec);

        int widthMode = MeasureSpec.getMode(widthMeasureSpec);

        int height = MeasureSpec.getSize(heightMeasureSpec);

        int heightMode = MeasureSpec.getMode(heightMeasureSpec);

 

        int childCount = getChildCount();

        measureChildren(widthMeasureSpec, heightMeasureSpec);

 

        if (childCount == 0) {

            setMeasuredDimension(0, 0);

        } else if (widthMode == MeasureSpec.AT_MOST && heightMode == MeasureSpec.AT_MOST) {

            height = getChildAt(0).getMeasuredHeight();

            width = childCount * getChildAt(0).getMeasuredWidth();

            setMeasuredDimension(width, height);

        } else if (widthMode == MeasureSpec.AT_MOST) {

            width = childCount * getChildAt(0).getMeasuredWidth();

            setMeasuredDimension(width, height);

        } else {

            height = getChildAt(0).getMeasuredHeight();

            setMeasuredDimension(width, height);

        }

    }

 

    @Override

    protected void onLayout(boolean changed, int l, int t, int r, int b) {

        int leftOffset = 0;

        for (int i = 0; i < getChildCount(); i++) {

            View child = getChildAt(i);

            child.layout(l + leftOffset, t, r + leftOffset, b);

            leftOffset += child.getMeasuredWidth();

        }

    }

 

    /**

     * 不拦截Down事件，其他一律拦截

     * @param ev

     * @return

     */

    @Override

    public boolean onInterceptTouchEvent(MotionEvent ev) {

        if (ev.getAction() == MotionEvent.ACTION_DOWN) {

            if (!mScroller.isFinished()) {

                mScroller.abortAnimation();

                return true;

            }

            return false;

        } else {

            return true;

        }

    }

 

    private boolean isFirstTouch = true;

 

    @Override

    public boolean onTouchEvent(MotionEvent event) {

        int x = (int) event.getX();

        int y = (int) event.getY();

        mVelocityTracker.addMovement(event);

        ViewConfiguration configuration = ViewConfiguration.get(getContext());

        switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:

                if (!mScroller.isFinished()) {

                    mScroller.abortAnimation();

                }

                break;

            case MotionEvent.ACTION_MOVE:

                if (isFirstTouch) {

                    isFirstTouch = false;

                    lastY = y;

                    lastX = x;

                }

                final int deltaX = x - lastX;

                scrollBy(-deltaX, 0);

                break;

            case MotionEvent.ACTION_UP:

                isFirstTouch = true;

                int scrollX = getScrollX();

                mVelocityTracker.computeCurrentVelocity(1000, configuration.getScaledMaximumFlingVelocity());

                float mVelocityX = mVelocityTracker.getXVelocity();

                if (Math.abs(mVelocityX) > configuration.getScaledMinimumFlingVelocity()) {

                    childIndex = mVelocityX < 0 ? childIndex + 1 : childIndex - 1;

                } else {

                    childIndex = (scrollX + getChildAt(0).getWidth() / 2) / getChildAt(0).getWidth();

                }

                childIndex = Math.min(getChildCount() - 1, Math.max(0, childIndex));

                smoothScrollBy(childIndex*getChildAt(0).getWidth()-scrollX,0);

                mVelocityTracker.clear();

                break;

        }

 

        lastX = x;

        lastY = y;

        return true;

    }

 

    private void smoothScrollBy(int dx, int dy) {

        mScroller.startScroll(getScrollX(), getScrollY(), dx, dy,500);

        invalidate();

    }

 

    @Override

    public void computeScroll() {

        if(mScroller.computeScrollOffset()){

            scrollTo(mScroller.getCurrX(),mScroller.getCurrY());

            postInvalidate();

        }

    }

 

    @Override

    protected void onDetachedFromWindow() {

        super.onDetachedFromWindow();

        mVelocityTracker.recycle();

    }

}

ListViewEx.java

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<code class="hljs java">

/**

 * Created by blueberry on 2016/6/20.

 * 内部拦截事件

 */

public class ListViewEx extends ListView {

 

    private int lastXIntercepted, lastYIntercepted;

 

    private HorizontalEx2 mHorizontalEx2;

 

    public ListViewEx(Context context) {

        super(context);

    }

 

    public ListViewEx(Context context, AttributeSet attrs) {

        super(context, attrs);

    }

 

    public ListViewEx(Context context, AttributeSet attrs, int defStyleAttr) {

        super(context, attrs, defStyleAttr);

    }

 

    public HorizontalEx2 getmHorizontalEx2() {

        return mHorizontalEx2;

    }

 

    public void setmHorizontalEx2(HorizontalEx2 mHorizontalEx2) {

        this.mHorizontalEx2 = mHorizontalEx2;

    }

 

    /**

     * 使用 outter.requestDisallowInterceptTouchEvent();

     * 来决定父控件是否对事件进行拦截

     * @param ev

     * @return

     */

    @Override

    public boolean dispatchTouchEvent(MotionEvent ev) {

        int x = (int) ev.getX();

        int y = (int) ev.getY();

        switch (ev.getAction()) {

            case MotionEvent.ACTION_DOWN:

                mHorizontalEx2.requestDisallowInterceptTouchEvent(true);

                break;

            case MotionEvent.ACTION_MOVE:

                final int deltaX = x-lastYIntercepted;

                final int deltaY = y-lastYIntercepted;

                if(Math.abs(deltaX)>Math.abs(deltaY)){

                    mHorizontalEx2.requestDisallowInterceptTouchEvent(false);

                }

                break;

            case MotionEvent.ACTION_UP:

                break;

        }

        lastXIntercepted = x;

        lastYIntercepted = y;

        return super.dispatchTouchEvent(ev);

    }

}

</code>

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<code class="hljs lasso"> @Override

    public void showInnerHVData(List<string> data1, List<string> data2, List<string> data3) {

 

        ListViewEx listView1 = new ListViewEx(getContext());

        ArrayAdapter<string> adapter1 = new ArrayAdapter<string>(getContext(), android.R.layout.simple_list_item_1, data1);

        listView1.setAdapter(adapter1);

        listView1.setmHorizontalEx2(mHorizontalEx2);

 

        ListViewEx listView2 = new ListViewEx(getContext());

        ArrayAdapter<string> adapter2 = new ArrayAdapter<string>(getContext(), android.R.layout.simple_list_item_1, data2);

        listView2.setAdapter(adapter2);

        listView2.setmHorizontalEx2(mHorizontalEx2);

 

        ListViewEx listView3 = new ListViewEx(getContext());

        ArrayAdapter<string> adapter3 = new ArrayAdapter<string>(getContext(), android.R.layout.simple_list_item_1, data3);

        listView3.setAdapter(adapter3);

        listView3.setmHorizontalEx2(mHorizontalEx2);

 

        ViewGroup.LayoutParams params

                = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,

                ViewGroup.LayoutParams.MATCH_PARENT);

 

        mHorizontalEx2.addView(listView1, params);

        mHorizontalEx2.addView(listView2, params);

        mHorizontalEx2.addView(listView3, params);

    }