Android ListView pull up to refresh 改造.

在上一个一个博客中介绍了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 {@link com.itaoo.view.PullToRefreshListView #onRefreshComplete()} is
         * expected to indicate that the refresh has completed.
         */
        public void onRefresh();
    }
}

评论

5 楼 pop1030123 2014-03-13  

cdhhappy 写道

博主您好，想请教您一个问题。
我之前也看过这个控件的实现，它有一个很大的问题就是当ListView的内容填不满一屏的时候，比如说ListView里面只有一项的时候，顶部的点击刷新的 button就不能隐藏了。
似乎新浪微薄的pullToRefresh ListView没有这个问题。

我现在在我的app里是自己实现了一个PullToRefresh控件，但是不是继承了ListView，而是从FrameLayout继承来的，所以当adapter的item数量较多的时候会对性能产生很大影响。非常容易crash。

对于这个问题的解决和新浪微薄客户端的是实现方法您有什么看法么。
多谢指教

请使用
https://github.com/fengcunhan/Android-PullToRefresh

4 楼 pop1030123 2014-03-13  

laineyhui 写道

我也遇到了同样的问题，就解答。谢谢

请使用
https://github.com/fengcunhan/Android-PullToRefresh

3 楼 guanting207 2013-05-31  

为什么我在模拟器上跑无法下拉啊

2 楼 laineyhui 2012-12-06  

我也遇到了同样的问题，就解答。谢谢

1 楼 cdhhappy 2011-10-09  

博主您好，想请教您一个问题。
我之前也看过这个控件的实现，它有一个很大的问题就是当ListView的内容填不满一屏的时候，比如说ListView里面只有一项的时候，顶部的点击刷新的 button就不能隐藏了。
似乎新浪微薄的pullToRefresh ListView没有这个问题。

我现在在我的app里是自己实现了一个PullToRefresh控件，但是不是继承了ListView，而是从FrameLayout继承来的，所以当adapter的item数量较多的时候会对性能产生很大影响。非常容易crash。

对于这个问题的解决和新浪微薄客户端的是实现方法您有什么看法么。
多谢指教