android安卓自定义listview实现下拉刷新

【1】、重写listView

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public class MyListView extends ListView implements OnScrollListener {  
  
    private final static int RELEASE_To_REFRESH = 0;// 下拉过程的状态值  
    private final static int PULL_To_REFRESH = 1; // 从下拉返回到不刷新的状态值  
    private final static int REFRESHING = 2;// 正在刷新的状态值  
    private final static int DONE = 3;  
    private final static int LOADING = 4;  
  
    // 实际的padding的距离与界面上偏移距离的比例  
    private final static int RATIO = 3;  
    private LayoutInflater inflater;  
  
    // ListView头部下拉刷新的布局  
    private LinearLayout headerView;  
    private TextView lvHeaderTipsTv;  
    private TextView lvHeaderLastUpdatedTv;  
    private ImageView lvHeaderArrowIv;  
    private ProgressBar lvHeaderProgressBar;  
  
    // 定义头部下拉刷新的布局的高度  
    private int headerContentHeight;  
  
    private RotateAnimation animation;  
    private RotateAnimation reverseAnimation;  
  
    private int startY;  
    private int state;  
    private boolean isBack;  
  
    // 用于保证startY的值在一个完整的touch事件中只被记录一次  
    private boolean isRecored;  
  
    private OnRefreshListener refreshListener;  
  
    private boolean isRefreshable;  
  
    public MyListView(Context context) {  
        super(context);  
        init(context);  
    }  
  
    public MyListView(Context context, AttributeSet attrs) {  
        super(context, attrs);  
        init(context);  
    }  
  
    private void init(Context context) {  
        setCacheColorHint(context.getResources().getColor(R.color.transparent));  
        inflater = LayoutInflater.from(context);  
        headerView = (LinearLayout) inflater.inflate(R.layout.lv_header, null);  
        lvHeaderTipsTv = (TextView) headerView  
                .findViewById(R.id.lvHeaderTipsTv);  
        lvHeaderLastUpdatedTv = (TextView) headerView  
                .findViewById(R.id.lvHeaderLastUpdatedTv);  
  
        lvHeaderArrowIv = (ImageView) headerView  
                .findViewById(R.id.lvHeaderArrowIv);  
        // 设置下拉刷新图标的最小高度和宽度  
        lvHeaderArrowIv.setMinimumWidth(70);  
        lvHeaderArrowIv.setMinimumHeight(50);  
  
        lvHeaderProgressBar = (ProgressBar) headerView  
                .findViewById(R.id.lvHeaderProgressBar);  
        measureView(headerView);  
        headerContentHeight = headerView.getMeasuredHeight();  
        // 设置内边距，正好距离顶部为一个负的整个布局的高度，正好把头部隐藏  
        headerView.setPadding(0, -1 * headerContentHeight, 0, 0);  
        // 重绘一下  
        headerView.invalidate();  
        // 将下拉刷新的布局加入ListView的顶部  
        addHeaderView(headerView, null, false);  
        // 设置滚动监听事件  
        setOnScrollListener(this);  
  
        // 设置旋转动画事件  
        animation = new RotateAnimation(0, -180,  
                RotateAnimation.RELATIVE_TO_SELF, 0.5f,  
                RotateAnimation.RELATIVE_TO_SELF, 0.5f);  
        animation.setInterpolator(new LinearInterpolator());  
        animation.setDuration(250);  
        animation.setFillAfter(true);  
  
        reverseAnimation = new RotateAnimation(-180, 0,  
                RotateAnimation.RELATIVE_TO_SELF, 0.5f,  
                RotateAnimation.RELATIVE_TO_SELF, 0.5f);  
        reverseAnimation.setInterpolator(new LinearInterpolator());  
        reverseAnimation.setDuration(200);  
        reverseAnimation.setFillAfter(true);  
  
        // 一开始的状态就是下拉刷新完的状态，所以为DONE  
        state = DONE;  
        // 是否正在刷新  
        isRefreshable = false;  
    }  
  
    @Override  
    public void onScrollStateChanged(AbsListView view, int scrollState) {  
  
    }  
  
    @Override  
    public void onScroll(AbsListView view, int firstVisibleItem,  
            int visibleItemCount, int totalItemCount) {  
                if (firstVisibleItem == 0) {  
                    isRefreshable = true;  
                 } else {  
                    isRefreshable = false;  
                 }     
        }  
  
    @Override  
    public boolean onTouchEvent(MotionEvent ev) {  
        if (isRefreshable) {  
            switch (ev.getAction()) {  
            case MotionEvent.ACTION_DOWN:  
                if (!isRecored) {  
                    isRecored = true;  
                    startY = (int) ev.getY();// 手指按下时记录当前位置  
                }  
                break;  
            case MotionEvent.ACTION_UP:  
                if (state != REFRESHING && state != LOADING) {  
                    if (state == PULL_To_REFRESH) {  
                        state = DONE;  
                        changeHeaderViewByState();  
                    }  
                    if (state == RELEASE_To_REFRESH) {  
                        state = REFRESHING;  
                        changeHeaderViewByState();  
                        onLvRefresh();  
                    }  
                }  
                isRecored = false;  
                isBack = false;  
  
                break;  
  
            case MotionEvent.ACTION_MOVE:  
                int tempY = (int) ev.getY();  
                if (!isRecored) {  
                    isRecored = true;  
                    startY = tempY;  
                }  
                if (state != REFRESHING && isRecored && state != LOADING) {  
                    // 保证在设置padding的过程中，当前的位置一直是在head，否则如果当列表超出屏幕的话，当在上推的时候，列表会同时进行滚动  
                    // 可以松手去刷新了  
                    if (state == RELEASE_To_REFRESH) {  
                        setSelection(0);  
                        // 往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步  
                        if (((tempY - startY) / RATIO < headerContentHeight)// 由松开刷新状态转变到下拉刷新状态  
                                && (tempY - startY) > 0) {  
                            state = PULL_To_REFRESH;  
                            changeHeaderViewByState();  
                        }  
                        // 一下子推到顶了  
                        else if (tempY - startY <= 0) {// 由松开刷新状态转变到done状态  
                            state = DONE;  
                            changeHeaderViewByState();  
                        }  
                    }  
                    // 还没有到达显示松开刷新的时候,DONE或者是PULL_To_REFRESH状态  
                    if (state == PULL_To_REFRESH) {  
                        setSelection(0);  
                        // 下拉到可以进入RELEASE_TO_REFRESH的状态  
                        if ((tempY - startY) / RATIO >= headerContentHeight) {// 由done或者下拉刷新状态转变到松开刷新  
                            state = RELEASE_To_REFRESH;  
                            isBack = true;  
                            changeHeaderViewByState();  
                        }  
                        // 上推到顶了  
                        else if (tempY - startY <= 0) {// 由DOne或者下拉刷新状态转变到done状态  
                            state = DONE;  
                            changeHeaderViewByState();  
                        }  
                    }  
                    // done状态下  
                    if (state == DONE) {  
                        if (tempY - startY > 0) {  
                            state = PULL_To_REFRESH;  
                            changeHeaderViewByState();  
                        }  
                    }  
                    // 更新headView的size  
                    if (state == PULL_To_REFRESH) {  
                        headerView.setPadding(0, -1 * headerContentHeight  
                                + (tempY - startY) / RATIO, 0, 0);  
  
                    }  
                    // 更新headView的paddingTop  
                    if (state == RELEASE_To_REFRESH) {  
                        headerView.setPadding(0, (tempY - startY) / RATIO  
                                - headerContentHeight, 0, 0);  
                    }  
  
                }  
                break;  
  
            default:  
                break;  
            }  
        }  
        return super.onTouchEvent(ev);  
    }  
  
    // 当状态改变时候，调用该方法，以更新界面  
    private void changeHeaderViewByState() {  
        switch (state) {  
        case RELEASE_To_REFRESH:  
            lvHeaderArrowIv.setVisibility(View.VISIBLE);  
            lvHeaderProgressBar.setVisibility(View.GONE);  
            lvHeaderTipsTv.setVisibility(View.VISIBLE);  
            lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);  
  
            lvHeaderArrowIv.clearAnimation();// 清除动画  
            lvHeaderArrowIv.startAnimation(animation);// 开始动画效果  
  
            lvHeaderTipsTv.setText("松开刷新");  
            break;  
        case PULL_To_REFRESH:  
            lvHeaderProgressBar.setVisibility(View.GONE);  
            lvHeaderTipsTv.setVisibility(View.VISIBLE);  
            lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);  
            lvHeaderArrowIv.clearAnimation();  
            lvHeaderArrowIv.setVisibility(View.VISIBLE);  
            // 是由RELEASE_To_REFRESH状态转变来的  
            if (isBack) {  
                isBack = false;  
                lvHeaderArrowIv.clearAnimation();  
                lvHeaderArrowIv.startAnimation(reverseAnimation);  
  
                lvHeaderTipsTv.setText("下拉刷新");  
            } else {  
                lvHeaderTipsTv.setText("下拉刷新");  
            }  
            break;  
  
        case REFRESHING:  
  
            headerView.setPadding(0, 0, 0, 0);  
  
            lvHeaderProgressBar.setVisibility(View.VISIBLE);  
            lvHeaderArrowIv.clearAnimation();  
            lvHeaderArrowIv.setVisibility(View.GONE);  
            lvHeaderTipsTv.setText("正在刷新...");  
            lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);  
            break;  
        case DONE:  
            headerView.setPadding(0, -1 * headerContentHeight, 0, 0);  
  
            lvHeaderProgressBar.setVisibility(View.GONE);  
            lvHeaderArrowIv.clearAnimation();  
            lvHeaderArrowIv.setImageResource(R.drawable.arrow);  
            lvHeaderTipsTv.setText("下拉刷新");  
            lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);  
            break;  
        }  
    }  
  
    // 此方法直接照搬自网络上的一个下拉刷新的demo，此处是“估计”headView的width以及height  
    private void measureView(View child) {  
        ViewGroup.LayoutParams params = child.getLayoutParams();  
        if (params == null) {  
            params = new ViewGroup.LayoutParams(  
                    ViewGroup.LayoutParams.FILL_PARENT,  
                    ViewGroup.LayoutParams.WRAP_CONTENT);  
        }  
        int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0,  
                params.width);  
        int lpHeight = params.height;  
        int childHeightSpec;  
        if (lpHeight > 0) {  
            childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,  
                    MeasureSpec.EXACTLY);  
        } else {  
            childHeightSpec = MeasureSpec.makeMeasureSpec(0,  
                    MeasureSpec.UNSPECIFIED);  
        }  
        child.measure(childWidthSpec, childHeightSpec);  
    }  
  
    public void setonRefreshListener(OnRefreshListener refreshListener) {  
        this.refreshListener = refreshListener;  
        isRefreshable = true;  
    }  
  
    public interface OnRefreshListener {  
        public void onRefresh();  
    }  
  
    public void onRefreshComplete() {  
        state = DONE;  
        lvHeaderLastUpdatedTv.setText("最近更新:" + new Date().toLocaleString());  
        changeHeaderViewByState();  
    }  
  
    private void onLvRefresh() {  
        if (refreshListener != null) {  
            refreshListener.onRefresh();  
        }  
    }  
  
    public void setAdapter(BaseAdapter  adapter) {  
        lvHeaderLastUpdatedTv.setText("最近更新:" + new Date().toLocaleString());  
        super.setAdapter(adapter);  
    }  
  
}

【2】刷新头部xml文件lv_header.xml

【3】调用方法

 adapter = new LvAdapter(list, this);  
        lv.setAdapter(adapter);  
  
        lv.setonRefreshListener(new OnRefreshListener() {  
  
            @Override  
            public void onRefresh() {  
                new AsyncTask() {  
                    protected Void doInBackground(Void... params) {  
                        try {  
                            Thread.sleep(1000);  
                        } catch (Exception e) {  
                            e.printStackTrace();  
                        }  
                        list.add("刷新后添加的内容");  
                        return null;  
                    }  
  
                    @Override  
                    protected void onPostExecute(Void result) {  
                        adapter.notifyDataSetChanged();  
                        lv.onRefreshComplete();  
                    }  
                }.execute(null, null, null);  
            }  
        });  
    }

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