Android系列之自定义ListView实现左右滑删除

效果图：



这里的话，就直接的给大家上代码解说了：

一、自己写一个类，继承ListView，然后重写一些相关的方法，如果有朋友嫌代码繁琐不想自己敲得话，可以直接cope我以下的代码去测试也可以

package com.zking.laci.android_project;

import android.widget.ListView;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.WindowManager;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Scroller;
/**
* Created by Laci on 2017/6/29.
*/

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.dispatchTouchEv
4000
ent(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

package com.zking.laci.android_project;

import android.app.Activity;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.preference.DialogPreference;
import android.support.annotation.IdRes;
import android.support.annotation.Nullable;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

import com.laci.application.MyApplication;
import com.laci.db.DbHelper;

import java.util.ArrayList;
import java.util.List;

/**
* Created by Laci on 2017/6/23.
*/

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;
}
}
}