Android 向下刷新列表
Android PullToRefresh为 Android 应用提供一个向下滑动即刷新列表的功能。
项目如图：
效果如图：
包含测试文件就2个目标文件！
主要类如下：
public class PullToRefreshListView extends ListView implements OnScrollListener { private static final int TAP_TO_REFRESH = 1; private static final int PULL_TO_REFRESH = 2; private static final int RELEASE_TO_REFRESH = 3; private static final int REFRESHING = 4; private static final String TAG = "PullToRefreshListView"; private OnRefreshListener mOnRefreshListener; /** * 收到通知的监听器每次滚动列表。 */ private OnScrollListener mOnScrollListener; private LayoutInflater mInflater; private RelativeLayout mRefreshView; private TextView mRefreshViewText; private ImageView mRefreshViewImage; private ProgressBar mRefreshViewProgress; private TextView mRefreshViewLastUpdated; private int mCurrentScrollState; private int mRefreshState; private RotateAnimation mFlipAnimation; private RotateAnimation mReverseFlipAnimation; private int mRefreshViewHeight; private int mRefreshOriginalTopPadding; private int mLastMotionY; private boolean mBounceHack; public PullToRefreshListView(Context context) { super(context); init(context); } public PullToRefreshListView(Context context, AttributeSet attrs) { super(context, attrs); init(context); } public PullToRefreshListView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(context); } private void init(Context context) { //我们需要在代码中加载所有的动画，而不是通过XML mFlipAnimation = new RotateAnimation(0, -180, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f); mFlipAnimation.setInterpolator(new LinearInterpolator()); mFlipAnimation.setDuration(250); mFlipAnimation.setFillAfter(true); mReverseFlipAnimation = new RotateAnimation(-180, 0, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f); mReverseFlipAnimation.setInterpolator(new LinearInterpolator()); mReverseFlipAnimation.setDuration(250); mReverseFlipAnimation.setFillAfter(true); mInflater = (LayoutInflater) context .getSystemService(Context.LAYOUT_INFLATER_SERVICE); mRefreshView = (RelativeLayout) mInflater.inflate( R.layout.pull_to_refresh_header, this, false); mRefreshViewText = (TextView) mRefreshView .findViewById(R.id.pull_to_refresh_text); mRefreshViewImage = (ImageView) mRefreshView .findViewById(R.id.pull_to_refresh_image); mRefreshViewProgress = (ProgressBar) mRefreshView .findViewById(R.id.pull_to_refresh_progress); mRefreshViewLastUpdated = (TextView) mRefreshView .findViewById(R.id.pull_to_refresh_updated_at); mRefreshViewImage.setMinimumHeight(50); mRefreshView.setOnClickListener(new OnClickRefreshListener()); mRefreshOriginalTopPadding = mRefreshView.getPaddingTop(); mRefreshState = TAP_TO_REFRESH; addHeaderView(mRefreshView); super.setOnScrollListener(this); measureView(mRefreshView); mRefreshViewHeight = mRefreshView.getMeasuredHeight(); } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); setSelection(1); } @Override public void setAdapter(ListAdapter adapter) { super.setAdapter(adapter); setSelection(1); } /** * 设置将接收通知的侦听器，每次滚动列表。 * @param l * The scroll listener. */ @Override public void setOnScrollListener(AbsListView.OnScrollListener l) { mOnScrollListener = l; } /** * 注册一个回调函数被调用时，此列表应被刷新。 * @param onRefreshListener * The callback to run. */ public void setOnRefreshListener(OnRefreshListener onRefreshListener) { mOnRefreshListener = onRefreshListener; } /** * 设置文本表示当列表的最后更新时间。 * @param lastUpdated * Last updated at. */ public void setLastUpdated(CharSequence lastUpdated) { if (lastUpdated != null) { mRefreshViewLastUpdated.setVisibility(View.VISIBLE); mRefreshViewLastUpdated.setText(lastUpdated); } else { mRefreshViewLastUpdated.setVisibility(View.GONE); } } @Override public boolean onTouchEvent(MotionEvent event) { final int y = (int) event.getY(); mBounceHack = false; switch (event.getAction()) { case MotionEvent.ACTION_UP: if (!isVerticalScrollBarEnabled()) { setVerticalScrollBarEnabled(true); } if (getFirstVisiblePosition() == 0 && mRefreshState != REFRESHING) { if ((mRefreshView.getBottom() >= mRefreshViewHeight || mRefreshView .getTop() >= 0) && mRefreshState == RELEASE_TO_REFRESH) { // Initiate the refresh mRefreshState = REFRESHING; prepareForRefresh(); onRefresh(); } else if (mRefreshView.getBottom() < mRefreshViewHeight || mRefreshView.getTop() <= 0) { // Abort refresh and scroll down below the refresh view resetHeader(); setSelection(1); } } break; case MotionEvent.ACTION_DOWN: mLastMotionY = y; break; case MotionEvent.ACTION_MOVE: applyHeaderPadding(event); break; } return super.onTouchEvent(event); } private void applyHeaderPadding(MotionEvent ev) { // getHistorySize has been available since API 1 int pointerCount = ev.getHistorySize(); for (int p = 0; p < pointerCount; p++) { if (mRefreshState == RELEASE_TO_REFRESH) { if (isVerticalFadingEdgeEnabled()) { setVerticalScrollBarEnabled(false); } int historicalY = (int) ev.getHistoricalY(p); // Calculate the padding to apply, we divide by 1.7 to // simulate a more resistant effect during pull. int topPadding = (int) (((historicalY - mLastMotionY) - mRefreshViewHeight) / 1.7); mRefreshView.setPadding(mRefreshView.getPaddingLeft(), topPadding, mRefreshView.getPaddingRight(), mRefreshView.getPaddingBottom()); } } } /** *设置的头部填充返回到原来的大小。 */ private void resetHeaderPadding() { mRefreshView.setPadding(mRefreshView.getPaddingLeft(), mRefreshOriginalTopPadding, mRefreshView.getPaddingRight(), mRefreshView.getPaddingBottom()); } /** * 复位到原来的状态的标头。 */ private void resetHeader() { if (mRefreshState != TAP_TO_REFRESH) { mRefreshState = TAP_TO_REFRESH; resetHeaderPadding(); // 将刷新视图文本拉标签 mRefreshViewText.setText(R.string.pull_to_refresh_tap_label); // Replace refresh drawable with arrow drawable mRefreshViewImage .setImageResource(R.drawable.ic_pulltorefresh_arrow); //清除旋转动画 mRefreshViewImage.clearAnimation(); // 隐藏进度条和箭头。 mRefreshViewImage.setVisibility(View.GONE); mRefreshViewProgress.setVisibility(View.GONE); } } private void measureView(View child) { ViewGroup.LayoutParams p = child.getLayoutParams(); if (p == null) { p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); } int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width); int lpHeight = p.height; int childHeightSpec; if (lpHeight > 0) { childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY); } else { childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); } child.measure(childWidthSpec, childHeightSpec); } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { // 当刷新的观点是完全可见的，改变的文字说：“放开刷新...”翻转的箭头绘制的。 if (mCurrentScrollState == SCROLL_STATE_TOUCH_SCROLL && mRefreshState != REFRESHING) { if (firstVisibleItem == 0) { mRefreshViewImage.setVisibility(View.VISIBLE); if ((mRefreshView.getBottom() >= mRefreshViewHeight + 20 || mRefreshView .getTop() >= 0) && mRefreshState != RELEASE_TO_REFRESH) { mRefreshViewText .setText(R.string.pull_to_refresh_release_label); mRefreshViewImage.clearAnimation(); mRefreshViewImage.startAnimation(mFlipAnimation); mRefreshState = RELEASE_TO_REFRESH; } else if (mRefreshView.getBottom() < mRefreshViewHeight + 20 && mRefreshState != PULL_TO_REFRESH) { mRefreshViewText .setText(R.string.pull_to_refresh_pull_label); if (mRefreshState != TAP_TO_REFRESH) { mRefreshViewImage.clearAnimation(); mRefreshViewImage.startAnimation(mReverseFlipAnimation); } mRefreshState = PULL_TO_REFRESH; } } else { mRefreshViewImage.setVisibility(View.GONE); resetHeader(); } } else if (mCurrentScrollState == SCROLL_STATE_FLING && firstVisibleItem == 0 && mRefreshState != REFRESHING) { setSelection(1); mBounceHack = true; } else if (mBounceHack && mCurrentScrollState == SCROLL_STATE_FLING) { setSelection(1); } if (mOnScrollListener != null) { mOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount); } } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { mCurrentScrollState = scrollState; if (mCurrentScrollState == SCROLL_STATE_IDLE) { mBounceHack = false; } if (mOnScrollListener != null) { mOnScrollListener.onScrollStateChanged(view, scrollState); } } public void prepareForRefresh() { resetHeaderPadding(); mRefreshViewImage.setVisibility(View.GONE); // 我们需要这个技巧，否则它会保持以前的drawable。 mRefreshViewImage.setImageDrawable(null); mRefreshViewProgress.setVisibility(View.VISIBLE); // 将刷新视图文本清爽的标签 mRefreshViewText.setText(R.string.pull_to_refresh_refreshing_label); mRefreshState = REFRESHING; } public void onRefresh() { Log.d(TAG, "onRefresh"); if (mOnRefreshListener != null) { mOnRefreshListener.onRefresh(); } } /** * 重置列表刷新后到正常状态。 * * @param lastUpdated * Last updated at. */ public void onRefreshComplete(CharSequence lastUpdated) { setLastUpdated(lastUpdated); onRefreshComplete(); } /** * 重置列表刷新后到正常状态。 */ public void onRefreshComplete() { Log.d(TAG, "onRefreshComplete"); resetHeader(); // 如果刷新视图是可见的，当加载完成，向下滚动到下一个项目。 if (mRefreshView.getBottom() > 0) { invalidateViews(); setSelection(1); } } /** * 点击刷新视图时调用。这主要是用于当有几个项目在列表中，这是不可能的拖动列表。 */ private class OnClickRefreshListener implements OnClickListener { @Override public void onClick(View v) { if (mRefreshState != REFRESHING) { prepareForRefresh(); onRefresh(); } } } /** *当列表被刷新的回调被调用的接口定义。 */ public interface OnRefreshListener { /** * 列表被刷新时调用的 * <p> * A call to {@link PullToRefreshListView #onRefreshComplete()} is * expected to indicate that the refresh has completed. */ public void onRefresh(); } }测试代码如下：
public class PullToRefreshActivity extends ListActivity { private LinkedList<String> mListItems; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.pull_to_refresh); // 设置一个监听器时要调用的列表被刷新。 ((PullToRefreshListView) getListView()) .setOnRefreshListener(new OnRefreshListener() { @Override public void onRefresh() { // 请刷新列表。 new GetDataTask().execute(); } }); mListItems = new LinkedList<String>(); mListItems.addAll(Arrays.asList(mStrings)); ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mListItems); setListAdapter(adapter); } private class GetDataTask extends AsyncTask<Void, Void, String[]> { @Override protected String[] doInBackground(Void... params) { //后台作业。 try { Thread.sleep(2000); } catch (InterruptedException e) { ; } return mStrings; } @Override protected void onPostExecute(String[] result) { mListItems.addFirst("Added after refresh..."); // 刷新完成 ((PullToRefreshListView) getListView()).onRefreshComplete(); super.onPostExecute(result); } } private String[] mStrings = { "Abbaye de Belloc", "Abbaye du Mont des Cats", "Abertam", "Abondance", "Ackawi", "Acorn", "Adelost", "Affidelice au Chablis", "Afuega'l Pitu", "Airag", "Airedale", "Aisy Cendre", "Allgauer Emmentaler" }; }
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