转自: http://dengyin2000.iteye.com/blog/1187823
android的UI组件，其中就包括了一个android-pulltorefresh组件。
https://github.com/johannilsson/android-pulltorefresh
这个组件是用在twitter微博中的， 往下拉列表的话， 顶部会自动load， 而且有反弹的效果，非常cool。 但是它的自动load顶部的内部， 我现在需要拖拉listview到最后的时候load。这个组件不知道方向的选择， 所以自己就动手改了下，实现从底部load。 （今天发现新浪微博也实现了同样的功能。） 附件是源码。
com.markupartist.android.widget.PullToRefreshListView
package com.markupartist.android.widget;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.LayoutInflater;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.view.animation.LinearInterpolator;import android.view.animation.RotateAnimation;import android.widget.*;import android.widget.AbsListView.OnScrollListener;import com.markupartist.android.widget.pulltorefresh.R;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;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; /** * Listener that will receive notifications every time the list scrolls. */ 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 mRefreshOriginalBottomPadding; private int mLastMotionY; 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) { // Load all of the animations we need in code rather than through 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(); mRefreshOriginalBottomPadding = mRefreshView.getPaddingBottom(); mRefreshState = TAP_TO_REFRESH;// addHeaderView(mRefreshView); addFooterView(mRefreshView); super.setOnScrollListener(this); measureView(mRefreshView); mRefreshViewHeight = mRefreshView.getMeasuredHeight(); } @Override protected void onAttachedToWindow() { //setSelection(1); } @Override public void setAdapter(ListAdapter adapter) { super.setAdapter(adapter); //setSelection(1); } /** * Set the listener that will receive notifications every time the list * scrolls. * * @param l The scroll listener. */ @Override public void setOnScrollListener(OnScrollListener l) { mOnScrollListener = l; } /** * Register a callback to be invoked when this list should be refreshed. * * @param onRefreshListener The callback to run. */ public void setOnRefreshListener(OnRefreshListener onRefreshListener) { mOnRefreshListener = onRefreshListener; } /** * Set a text to represent when the list was last updated. * * @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(); switch (event.getAction()) { case MotionEvent.ACTION_UP: if (!isVerticalScrollBarEnabled()) { setVerticalScrollBarEnabled(true); } if (getLastVisiblePosition() == getAdapter().getCount() - 1 && mRefreshState != REFRESHING) { if (( mRefreshView.getTop() <= getMeasuredHeight() - mRefreshViewHeight) && mRefreshState == RELEASE_TO_REFRESH) { // Initiate the refresh mRefreshState = REFRESHING; prepareForRefresh(); onRefresh(); } else if (mRefreshView.getTop() > getMeasuredHeight() - mRefreshViewHeight) { // Abort refresh and scroll down below the refresh view resetHeader(); //setSelection(1); if (getFooterViewsCount() > 0) { setSelectionFromTop(getAdapter().getCount() - 1, (this.getMeasuredHeight())); }// if (mRefreshState != RELEASE_TO_REFRESH){// scrollTo(0, mRefreshView.getScrollY() - mRefreshViewHeight);// } } } break; case MotionEvent.ACTION_DOWN: mLastMotionY = y; break; case MotionEvent.ACTION_MOVE: applyHeaderPadding(event); break; } return super.onTouchEvent(event); } private void applyHeaderPadding(MotionEvent ev) { final int historySize = ev.getHistorySize(); // Workaround for getPointerCount() which is unavailable in 1.5 // (it's always 1 in 1.5) int pointerCount = 1; try { Method method = MotionEvent.class.getMethod("getPointerCount"); pointerCount = (Integer) method.invoke(ev); } catch (NoSuchMethodException e) { pointerCount = 1; } catch (IllegalArgumentException e) { throw e; } catch (IllegalAccessException e) { System.err.println("unexpected " + e); } catch (InvocationTargetException e) { System.err.println("unexpected " + e); }// Log.i("PullToRefreshListView", "historySize:" + historySize);// Log.i("PullToRefreshListView", "pointerCount:" + pointerCount);// Log.i("PullToRefreshListView", " ");// Log.i("PullToRefreshListView", " ");// Log.i("PullToRefreshListView", " "); for (int h = 0; h < historySize; h++) { for (int p = 0; p < pointerCount; p++) { if (mRefreshState == RELEASE_TO_REFRESH) { if (isVerticalFadingEdgeEnabled()) { setVerticalScrollBarEnabled(false); } int historicalY = 0; try { // For Android > 2.0 Method method = MotionEvent.class.getMethod( "getHistoricalY", Integer.TYPE, Integer.TYPE); historicalY = ((Float) method.invoke(ev, p, h)).intValue(); } catch (NoSuchMethodException e) { // For Android < 2.0 historicalY = (int) (ev.getHistoricalY(h)); } catch (IllegalArgumentException e) { throw e; } catch (IllegalAccessException e) { System.err.println("unexpected " + e); } catch (InvocationTargetException e) { System.err.println("unexpected " + e); } // 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(), mRefreshView.getPaddingTop(), mRefreshView.getPaddingRight(), topPadding); } } } } /** * Sets the header padding back to original size. */ private void resetHeaderPadding() { mRefreshView.setPadding( mRefreshView.getPaddingLeft(), mRefreshView.getPaddingTop(), mRefreshView.getPaddingRight(), mRefreshOriginalBottomPadding); } /** * Resets the header to the original state. */ private void resetHeader() { if (mRefreshState != TAP_TO_REFRESH) { mRefreshState = TAP_TO_REFRESH; resetHeaderPadding(); // Set refresh view text to the pull label mRefreshViewText.setText(R.string.pull_to_refresh_tap_label); // Replace refresh drawable with arrow drawable mRefreshViewImage.setImageResource(R.drawable.ic_pulltorefresh_arrow); // Clear the full rotation animation mRefreshViewImage.clearAnimation(); // Hide progress bar and arrow. 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) {// Log.i("PullToRefreshListView", "firstVisibleItem:" + firstVisibleItem);// Log.i("PullToRefreshListView", "visibleItemCount:" + visibleItemCount);// Log.i("PullToRefreshListView", "totalItemCount:" + totalItemCount);// Log.i("PullToRefreshListView", "");// Log.i("PullToRefreshListView", "");// Log.i("PullToRefreshListView", ""); // When the refresh view is completely visible, change the text to say // "Release to refresh..." and flip the arrow drawable. if (mCurrentScrollState == SCROLL_STATE_TOUCH_SCROLL && mRefreshState != REFRESHING) { if (firstVisibleItem + visibleItemCount == totalItemCount) { mRefreshViewImage.setVisibility(View.VISIBLE); if (( mRefreshView.getTop() <= getMeasuredHeight() - mRefreshViewHeight) && 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.getTop() > getMeasuredHeight() - 20 - mRefreshViewHeight && 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 && getLastVisiblePosition() >= getAdapter().getCount() -1 && mRefreshState != REFRESHING) { if (getFooterViewsCount() > 0) { setSelectionFromTop(getAdapter().getCount() - 1, (this.getMeasuredHeight())); } } if (mOnScrollListener != null) { mOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount); } } public View getLoadBarView() { return mRefreshView; } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { mCurrentScrollState = scrollState; if (mOnScrollListener != null) { mOnScrollListener.onScrollStateChanged(view, scrollState); } } public void prepareForRefresh() { resetHeaderPadding(); mRefreshViewImage.setVisibility(View.GONE); // We need this hack, otherwise it will keep the previous drawable. mRefreshViewImage.setImageDrawable(null); mRefreshViewProgress.setVisibility(View.VISIBLE); // Set refresh view text to the refreshing label mRefreshViewText.setText(R.string.pull_to_refresh_refreshing_label); mRefreshState = REFRESHING; } public void onRefresh() { Log.d(TAG, "onRefresh"); if (mOnRefreshListener != null) { mOnRefreshListener.onRefresh(); } } /** * Resets the list to a normal state after a refresh. * * @param lastUpdated Last updated at. */ public void onRefreshComplete(CharSequence lastUpdated) { setLastUpdated(lastUpdated); onRefreshComplete(); } /** * Resets the list to a normal state after a refresh. */ public void onRefreshComplete() { Log.d(TAG, "onRefreshComplete"); resetHeader(); // If refresh view is visible when loading completes, scroll down to // the next item. if (mRefreshView.getBottom() > 0) { invalidateViews(); //setSelection(1); } } /** * Invoked when the refresh view is clicked on. This is mainly used when * there's only a few items in the list and it's not possible to drag the * list. */ private class OnClickRefreshListener implements OnClickListener { @Override public void onClick(View v) { if (mRefreshState != REFRESHING) { prepareForRefresh(); onRefresh(); } } } /** * Interface definition for a callback to be invoked when list should be * refreshed. */ public interface OnRefreshListener { /** * Called when the list should be refreshed. * <p/> * A call to [email protected] com.itaoo.view.PullToRefreshListView #onRefreshComplete()} is * expected to indicate that the refresh has completed. */ public void onRefresh(); }} 1 楼 zhoujiamail 2011-12-02
请问一下如果用这种方法实现头部刷新效果，当ListView里的列表项很少时是隐藏不掉的，有什么别的办法可以做到吗