ListView的下拉刷新、滑动删除和上拉加载更多

曾经终败给现在 2022-07-16 13:22 190阅读 0赞

实现思路：

1、在ListView中添加header并在开始时隐藏，通过设置header的topPadding为负的header的高度，实现该效果

2、监听手势（用onTouchEvent），先判断ListView是否已经到达顶部，到达顶部以后根据滑动幅度（手指还没有抬起来）可分为两种状态，一种是幅度不够，则松开手指后LiveView恢复原样，一种是下拉幅度够了则更改header中的View信息，第三种状态是正在刷新，在松开手指时更新为该状态

3、ListView的滑动监听，如果在滑动时为状态3，则开启线程更新ListView中的数据（借助handler）

效果图：

![Center][]

![Center 1][]

![Center 2][]

**header布局：**

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        
    
        <FrameLayout
            android:id="@+id/fl"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="120dp">
            <ImageView
                android:id="@+id/refresh"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:src="@drawable/pull_to_refresh_arrow" />
    
            <ProgressBar
                android:id="@+id/progress"
                style="@style/Widget.AppCompat.ProgressBar"
                android:layout_gravity="center"
                android:max="100"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:visibility="gone" />
    
        </FrameLayout>
    
       
        <LinearLayout
            android:id="@+id/ly"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_toRightOf="@id/fl"
            android:gravity="center_horizontal"
            android:orientation="vertical"
            android:paddingBottom="10dp"
            android:paddingLeft="10dp"
            android:paddingRight="10dp"
            android:paddingTop="10dp">
    
            <TextView
                android:id="@+id/tip"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:gravity="center_horizontal"
                android:text="下拉刷新"
                android:textSize="15sp" />
    
            <TextView
                android:id="@+id/update_last_time"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:gravity="center_horizontal" />
    
        </LinearLayout>
    
    
    </RelativeLayout>

**mainActivity布局：**

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/activity_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        tools:context="com.example.he.sample.MainActivity">
    
        <com.example.he.sample.myListView
            android:id="@+id/lv"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"></com.example.he.sample.myListView>
    </RelativeLayout>

**myListView：**

/**
     * header下拉时的三种种状态，UN_PREPARE表示滑动的幅度不够不需要刷新，PREPARE表示的含义是现在松手就能刷新，REFRESH表示正在刷新
     */
    enum State {
        UN_PREPARE, PREPARE, REFRESH
    }
    
    
    public class myListView extends ListView {
    
        private View header;
        private int headerHeight;
        private int startY;
        private boolean top;//用于判断是否在顶部滑动
        private boolean firstState = true;//是否是第一次进行状态判断
    
        private State state = State.UN_PREPARE;//滑动的状态，用于listView滑动事件的处理，见MainActivity.class
    
        private TextView title;
        private ImageView image;
        private ProgressBar bar;
    
        public myListView(Context context, AttributeSet attrs, int defStyleAttr) {
            super(context, attrs, defStyleAttr);
            initView(context);
        }
    
        public myListView(Context context) {
            super(context);
            initView(context);
    
        }
    
        public myListView(Context context, AttributeSet attrs) {
            super(context, attrs);
            initView(context);
        }
    
        /**
         * 加载header视图
         *
         * @param context
         */
        private void initView(Context context) {
            header = LayoutInflater.from(context).inflate(R.layout.head, null);
            title = (TextView) header.findViewById(R.id.tip);
            image = (ImageView) header.findViewById(R.id.refresh);
            bar = (ProgressBar) header.findViewById(R.id.progress);
            header.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);//测量head
            headerHeight = header.getMeasuredHeight();//获取高度
            topPadding(-headerHeight);
            this.addHeaderView(header);
        }
    
        /**
         * 修改header的PaddingTop值达到隐藏header、随着滑动慢慢出现的效果
         *
         * @param topPadding
         */
        protected void topPadding(int topPadding) {
            header.setPadding(header.getPaddingLeft(), topPadding,
                    header.getPaddingRight(), header.getPaddingBottom());
            header.invalidate();
        }
    
    
        @Override
        public boolean onTouchEvent(MotionEvent ev) {
    
            switch (ev.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    int t = this.getFirstVisiblePosition();
                    //t为0表示到达屏幕顶部
                    if (t == 0) {
                        top = true;
                        startY = (int) ev.getY();
                    }
                    break;
                case MotionEvent.ACTION_UP:
                    top = false;
                    firstState = true;
                    //在状态2时松手则切换到状态3的视图
                    if (state == State.PREPARE)
                        refreshView(State.REFRESH, 0);
                    //在状态1时松手则恢复原样
                    if (state == State.UN_PREPARE)
                        topPadding(-headerHeight);
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (top)
                        onMove(ev);
    
                    break;
            }
    
            return super.onTouchEvent(ev);
        }
    
    
        /**
         * 手指正在滑动时进行状态判断
         * @param event
         */
        private void onMove(MotionEvent event) {
            int lastY = (int) event.getY();
            int space = lastY - startY;
            int padding = space - headerHeight;
            Log.i("padding", "" + padding);
            //状态1
            if (padding < 30) {
                Log.i("state", "1");
                if (firstState)
                    refreshView(State.UN_PREPARE, padding);
            }
            //状态2
            else if (padding > 30 && padding < 100) {
                firstState = false;
                refreshView(State.PREPARE, padding);
            }
    
        }
    
    
        /**
         * 根据不同的状态，完成相应的操作
         */
        private void refreshView(State s, int padding) {
            switch (s) {
                case UN_PREPARE:
                    topPadding(padding);
                    state = State.UN_PREPARE;//更新状态
                    bar.setVisibility(View.GONE);
                    image.setVisibility(View.VISIBLE);
                    title.setText("下拉刷新");
    
                    break;
                case PREPARE:
                    image.setVisibility(View.VISIBLE);
                    bar.setVisibility(View.GONE);
                    topPadding(padding);
                    state = State.PREPARE;//更新状态
    
                    //更新header中的视图
                    /**
                     * 创建旋转动画达到向下的箭头朝上的目的,旋转180度，以自身为中心
                     */
                    RotateAnimation animation = new RotateAnimation(0, 180, RotateAnimation.RELATIVE_TO_SELF, 0.5F, RotateAnimation.RELATIVE_TO_SELF, 0.5F);
                    animation.setDuration(0);//0毫秒内完成效果
                   animation.setFillAfter(true);//图片的显示为执行动画后的样子
                    image.startAnimation(animation);
                    title.setText("松手进行刷新");
    
                    topPadding(padding);
                    break;
                case REFRESH:
                    image.setVisibility(View.GONE);//隐藏image
                    bar.setVisibility(View.VISIBLE);//显示bar
                    //更新header中的视图
                    image.clearAnimation();//清除image上的动画
                    title.setText("正在刷新");
                    state = State.REFRESH;//更新状态
                    break;
            }
        }
    
        public int getHeaderHeight() {
            return headerHeight;
        }
        public State getState() {
            return state;
        }
    
    }

**MainActivity：**

public class MainActivity extends AppCompatActivity {
        private static final int OK = 1;
    
    
        private myListView listView;
        private ArrayAdapter<Integer> adapter;
        private int headerHeight;
        private List<Integer> list;
        private Random random = new Random(47);//随机数
        private Handler handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                switch (msg.what) {
                    case OK:
                        adapter.notifyDataSetChanged();//刷新数据
                        listView.topPadding(-headerHeight);//隐藏header
                        break;
                }
            }
        };
    
    
        @Override
        protected void onCreate(final Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            listView = (myListView) findViewById(R.id.lv);
            headerHeight = listView.getHeaderHeight();
            list = new ArrayList<Integer>();
            initList();
            adapter = new ArrayAdapter<Integer>(this, android.R.layout.simple_list_item_1, list);
            listView.setAdapter(adapter);
    
    
            /**
             * listView的滑动监听
             */
            listView.setOnScrollListener(new AbsListView.OnScrollListener() {
                @Override
                public void onScrollStateChanged(AbsListView view, int scrollState) {
                    //正在刷新则刷新数据
                    if (listView.getState() == State.REFRESH) {
                        onRefresh();
                    }
                }
    
                @Override
                public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
    
                }
            });
    
        }
    
        private void initList() {
            for (int i = 0; i < 50; i++) {
                list.add(random.nextInt(50));
            }
    
        }
    
        /**
         * 更新数据
         */
        private void onRefresh() {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    Message message = new Message();
                    message.what = OK;
                    for (int i : list) {
                        list.set(i, random.nextInt(50));
                    }
                    handler.sendMessageDelayed(message, 2000);//2s以后发送message
                }
            }).start();
        }
    
    }

**源码地址：[点击打开链接][Link 1]**

在自己实现的下拉刷新的基础上添加了ListView的滑动删除，关于滑动删除的教程请看这篇文章：[点击打开链接][Link 2]，但是这位博主的代码是不适合添加了header的ListView的，如果完全按文中代码加到我这个项目中会出现部分item无法滑动的问题，只需将文中的

//我们想知道当前点击了哪一行  
                int position = pointToPosition(x, y);  
                if (position != INVALID_POSITION) {  
                    DataHolder data = (DataHolder) getItemAtPosition(position);  
                    itemRoot = data.rootView;  
                }

修改为

int position = pointToPosition(x, y);
    int firstPosition = getFirstVisiblePosition();
    if (position != INVALID_POSITION) {
    curView = (ScrollDeleteLinearLayout) getChildAt(position - firstPosition);
    }

其实官方给我们提供了**SwipeRefreshLayout**可用于ListView的刷新，它已经帮我们把内部实现封装好了，**Demo：**[点击打开链接][Link 3]

ListView的上拉加载更多和下拉刷新的代码基本上是一样的，只不过不是添加header而是添加footer，其他实现基本相同，有个要注意的地方是，由于ListView添加数据能直接显示出来，所以添加的位置要做变动否则看不出效果

**下拉加载更多的Demo：**[点击打开链接][Link 4]

[Center]: /images/20220715/81f5af4a9d3c4a4ca5615b7d0c1048a7.png
[Center 1]: /images/20220715/e4161bc7828f479698c0aa4acbda8a5f.png
[Center 2]: /images/20220715/779dd0edb75549088ae442dec4536a9f.png
[Link 1]: https://github.com/xiaoyuzdy/learnAndroid/tree/master/MyApplication/Sample
[Link 2]: http://blog.csdn.net/harvic880925/article/details/45155965
[Link 3]: https://github.com/xiaoyuzdy/learnAndroid/tree/master/MyApplication/SwipeRefreshLayout
[Link 4]: https://github.com/xiaoyuzdy/learnAndroid/tree/master/MyApplication/MyApplication