Android系列之自定义ListView实现左右滑删除

一、自己写一个类，继承ListView，然后重写一些相关的方法

public class SlideCutListView extends ListView{/**  * 当前滑动的ListView　position  */  private int slidePosition;      /**      * 手指按下X的坐标      */      private int downY;      /**      * 手指按下Y的坐标      */      private int downX;      /**      * 屏幕宽度      */      private int screenWidth;      /**      * ListView的item      */      private View itemView;      /**      * 滑动类      */      private Scroller scroller;      private static final int SNAP_VELOCITY = 600;      /**      * 速度追踪对象      */      private VelocityTracker velocityTracker;      /**      * 是否响应滑动，默认为不响应      */      private boolean isSlide = false;      /**      * 认为是用户滑动的最小距离      */      private int mTouchSlop;      /**      *  移除item后的回调接口      */      private RemoveListener mRemoveListener;      /**      * 用来指示item滑出屏幕的方向,向左或者向右,用一个枚举值来标记      */      private RemoveDirection removeDirection;        // 滑动删除方向的枚举值      public enum RemoveDirection {          RIGHT, LEFT;      }          public SlideCutListView(Context context) {          this(context, null);      }        public SlideCutListView(Context context, AttributeSet attrs) {          this(context, attrs, 0);      }        public SlideCutListView(Context context, AttributeSet attrs, int defStyle) {          super(context, attrs, defStyle);          screenWidth = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay().getWidth();          scroller = new Scroller(context);          mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();      }        /**      * 设置滑动删除的回调接口      * @param removeListener      */      public void setRemoveListener(RemoveListener removeListener) {          this.mRemoveListener = removeListener;      }        /**      * 分发事件，主要做的是判断点击的是那个item, 以及通过postDelayed来设置响应左右滑动事件      */      @Override      public boolean dispatchTouchEvent(MotionEvent event) {          switch (event.getAction()) {              case MotionEvent.ACTION_DOWN: {                  addVelocityTracker(event);                    // 假如scroller滚动还没有结束，我们直接返回                  if (!scroller.isFinished()) {                      return super.dispatchTouchEvent(event);                  }                  downX = (int) event.getX();                  downY = (int) event.getY();                    slidePosition = pointToPosition(downX, downY);                    // 无效的position, 不做任何处理                  if (slidePosition == AdapterView.INVALID_POSITION) {                      return super.dispatchTouchEvent(event);                  }                    // 获取我们点击的item view                  itemView = getChildAt(slidePosition - getFirstVisiblePosition());                  break;              }              case MotionEvent.ACTION_MOVE: {                  if (Math.abs(getScrollVelocity()) > SNAP_VELOCITY                          || (Math.abs(event.getX() - downX) > mTouchSlop && Math                          .abs(event.getY() - downY) < mTouchSlop)) {                      isSlide = true;                    }                  break;              }              case MotionEvent.ACTION_UP:                  recycleVelocityTracker();                  break;          }            return super.dispatchTouchEvent(event);      }        /**      * 往右滑动，getScrollX()返回的是左边缘的距离，就是以View左边缘为原点到开始滑动的距离，所以向右边滑动为负值      */      private void scrollRight() {          removeDirection = RemoveDirection.RIGHT;          final int delta = (screenWidth + itemView.getScrollX());          // 调用startScroll方法来设置一些滚动的参数，我们在computeScroll()方法中调用scrollTo来滚动item          scroller.startScroll(itemView.getScrollX(), 0, -delta, 0,                  Math.abs(delta));          postInvalidate(); // 刷新itemView      }        /**      * 向左滑动，根据上面我们知道向左滑动为正值      */      private void scrollLeft() {          removeDirection = RemoveDirection.LEFT;          final int delta = (screenWidth - itemView.getScrollX());          // 调用startScroll方法来设置一些滚动的参数，我们在computeScroll()方法中调用scrollTo来滚动item          scroller.startScroll(itemView.getScrollX(), 0, delta, 0,                  Math.abs(delta));          postInvalidate(); // 刷新itemView      }        /**      * 根据手指滚动itemView的距离来判断是滚动到开始位置还是向左或者向右滚动      */      private void scrollByDistanceX() {          // 如果向左滚动的距离大于屏幕的二分之一，就让其删除          if (itemView.getScrollX() >= screenWidth / 2) {              scrollLeft();          } else if (itemView.getScrollX() <= -screenWidth / 2) {              scrollRight();          } else {              // 滚回到原始位置,为了偷下懒这里是直接调用scrollTo滚动              itemView.scrollTo(0, 0);          }        }        /**      * 处理我们拖动ListView item的逻辑      */      @Override      public boolean onTouchEvent(MotionEvent ev) {          if (isSlide && slidePosition != AdapterView.INVALID_POSITION) {              requestDisallowInterceptTouchEvent(true);              addVelocityTracker(ev);              final int action = ev.getAction();              int x = (int) ev.getX();              switch (action) {                  case MotionEvent.ACTION_DOWN:                      break;                  case MotionEvent.ACTION_MOVE:                        MotionEvent cancelEvent = MotionEvent.obtain(ev);                      cancelEvent.setAction(MotionEvent.ACTION_CANCEL |                              (ev.getActionIndex()<< MotionEvent.ACTION_POINTER_INDEX_SHIFT));                      onTouchEvent(cancelEvent);                        int deltaX = downX - x;                      downX = x;                        // 手指拖动itemView滚动, deltaX大于0向左滚动，小于0向右滚                      itemView.scrollBy(deltaX, 0);                        return true;  //拖动的时候ListView不滚动                  case MotionEvent.ACTION_UP:                      int velocityX = getScrollVelocity();                      if (velocityX > SNAP_VELOCITY) {                          scrollRight();                      } else if (velocityX < -SNAP_VELOCITY) {                          scrollLeft();                      } else {                          scrollByDistanceX();                      }                        recycleVelocityTracker();                      // 手指离开的时候就不响应左右滚动                      isSlide = false;                      break;              }          }            //否则直接交给ListView来处理onTouchEvent事件          return super.onTouchEvent(ev);      }        @Override      public void computeScroll() {          // 调用startScroll的时候scroller.computeScrollOffset()返回true，          if (scroller.computeScrollOffset()) {              // 让ListView item根据当前的滚动偏移量进行滚动              itemView.scrollTo(scroller.getCurrX(), scroller.getCurrY());                postInvalidate();                // 滚动动画结束的时候调用回调接口              if (scroller.isFinished()) {                  if (mRemoveListener == null) {                      throw new NullPointerException("RemoveListener is null, we should called setRemoveListener()");                  }                    itemView.scrollTo(0, 0);                  mRemoveListener.removeItem(removeDirection, slidePosition);              }          }      }        /**      * 添加用户的速度跟踪器      *      * @param event      */      private void addVelocityTracker(MotionEvent event) {          if (velocityTracker == null) {              velocityTracker = VelocityTracker.obtain();          }            velocityTracker.addMovement(event);      }        /**      * 移除用户速度跟踪器      */      private void recycleVelocityTracker() {          if (velocityTracker != null) {              velocityTracker.recycle();              velocityTracker = null;          }      }        /**      * 获取X方向的滑动速度,大于0向右滑动，反之向左      *      * @return      */      private int getScrollVelocity() {          velocityTracker.computeCurrentVelocity(1000);          int velocity = (int) velocityTracker.getXVelocity();          return velocity;      }        /**      *      * 当ListView item滑出屏幕，回调这个接口      * 我们需要在回调方法removeItem()中移除该Item,然后刷新ListView      *      * @author xiaanming      *      */      public interface RemoveListener {          public void removeItem(RemoveDirection direction, int position);      }    }  

二、然后在xml中使用自己定义的类

<?xml version="1.0" encoding="utf-8"?>  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      android:orientation="vertical" android:layout_width="match_parent"      android:layout_height="match_parent"      android:background="#FFFFFF"      >      <com.zking.laci.android_project.SlideCutListView          android:layout_width="match_parent"          android:layout_height="match_parent"          android:listSelector="@android:color/transparent"          android:id="@+id/sv_slidecutlistview"          android:cacheColorHint="@android:color/transparent"          android:background="#EBEBEB"          ></com.zking.laci.android_project.SlideCutListView>    </LinearLayout>  

三、然后在activity里面实现自定义类，写上相对应的代码块就可以直接使用了

public class CollectionActivity extends Activity implements SlideCutListView.RemoveListener{      private SlideCutListView slideCutListView;      private List<String> lt=new ArrayList<>();      private ArrayAdapter aa;        @Override      protected void onCreate(@Nullable Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_collection);          slideCutListView = (SlideCutListView) findViewById(R.id.sv_slidecutlistview);          slideCutListView.setRemoveListener(this);          //设置适配器          aa = new ArrayAdapter(this, R.layout.list_item,R.id.tv_list_item,lt);            slideCutListView.setAdapter(aa);      }      @Override      public void removeItem(SlideCutListView.RemoveDirection direction, final int position) {            switch (direction){              case RIGHT:                  Toast.makeText(this, "RIGHT", Toast.LENGTH_SHORT).show();                  break;              case LEFT:                  Toast.makeText(this, "LEFT", Toast.LENGTH_SHORT).show();                  break;              default:                  break;          }      }  }