完美ExpandableListView仿QQ列表，可扩展性强

package com.iaiai; import android.content.Context; import android.graphics.Canvas; import android.util.AttributeSet; import android.util.Log; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.widget.AbsListView; import android.widget.AbsListView.OnScrollListener; import android.widget.ExpandableListAdapter; import android.widget.ExpandableListView; import android.widget.ExpandableListView.OnGroupClickListener; import android.widget.ImageView; import android.widget.TextView; public class QQListView extends ExpandableListView implements OnScrollListener,OnGroupClickListener { public QQListView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); registerListener(); } public QQListView(Context context, AttributeSet attrs) { super(context, attrs); registerListener(); } public QQListView(Context context) { super(context); registerListener(); } /** * Adapter 接口 . 列表必须实现此接口 . */ public interface QQHeaderAdapter { public static final int PINNED_HEADER_GONE = 0; public static final int PINNED_HEADER_VISIBLE = 1; public static final int PINNED_HEADER_PUSHED_UP = 2; /** * 获取 Header 的状态 * @param groupPosition * @param childPosition * @return PINNED_HEADER_GONE,PINNED_HEADER_VISIBLE,PINNED_HEADER_PUSHED_UP 其中之一 */ int getQQHeaderState(int groupPosition, int childPosition); /** * 配置 QQHeader, 让 QQHeader 知道显示的内容 * @param header * @param groupPosition * @param childPosition * @param alpha */ void configureQQHeader(View header, int groupPosition,int childPosition, int alpha); /** * 设置组按下的状态 * @param groupPosition * @param status */ void setGroupClickStatus(int groupPosition, int status); /** * 获取组按下的状态 * @param groupPosition * @return */ int getGroupClickStatus(int groupPosition); } private static final int MAX_ALPHA = 255; private QQHeaderAdapter mAdapter; /** * 用于在列表头显示的 View,mHeaderViewVisible 为 true 才可见 */ private View mHeaderView; /** * 列表头是否可见 */ private boolean mHeaderViewVisible; private int mHeaderViewWidth; private int mHeaderViewHeight; public void setHeaderView(View view) { mHeaderView = view; AbsListView.LayoutParams lp = new AbsListView.LayoutParams( ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); view.setLayoutParams(lp); if (mHeaderView != null) { setFadingEdgeLength(0); } requestLayout(); } private void registerListener() { setOnScrollListener(this); setOnGroupClickListener(this); } /** * 点击 HeaderView 触发的事件 */ private void headerViewClick() { long packedPosition = getExpandableListPosition(this.getFirstVisiblePosition()); int groupPosition = ExpandableListView.getPackedPositionGroup(packedPosition); if (mAdapter.getGroupClickStatus(groupPosition) == 1) { this.collapseGroup(groupPosition); mAdapter.setGroupClickStatus(groupPosition, 0); } else{ this.expandGroup(groupPosition); mAdapter.setGroupClickStatus(groupPosition, 1); } this.setSelectedGroup(groupPosition); } private float mDownX; private float mDownY; /** * 如果 HeaderView 是可见的 , 此函数用于判断是否点击了 HeaderView, 并对做相应的处理 , * 因为 HeaderView 是画上去的 , 所以设置事件监听是无效的 , 只有自行控制 . */ @Override public boolean onTouchEvent(MotionEvent ev) { if (mHeaderViewVisible) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: mDownX = ev.getX(); mDownY = ev.getY(); if (mDownX <= mHeaderViewWidth && mDownY <= mHeaderViewHeight) { return true; } break; case MotionEvent.ACTION_UP: float x = ev.getX(); float y = ev.getY(); float offsetX = Math.abs(x - mDownX); float offsetY = Math.abs(y - mDownY); // 如果 HeaderView 是可见的 , 点击在 HeaderView 内 , 那么触发 headerClick() if (x <= mHeaderViewWidth && y <= mHeaderViewHeight && offsetX <= mHeaderViewWidth && offsetY <= mHeaderViewHeight) { if (mHeaderView != null) { headerViewClick(); } return true; } break; default: break; } } return super.onTouchEvent(ev); } @Override public void setAdapter(ExpandableListAdapter adapter) { super.setAdapter(adapter); mAdapter = (QQHeaderAdapter) adapter; } /** * * 点击了 Group 触发的事件 , 要根据根据当前点击 Group 的状态来 */ @Override public boolean onGroupClick(ExpandableListView parent,View v,int groupPosition,long id) { if (mAdapter.getGroupClickStatus(groupPosition) == 0) { mAdapter.setGroupClickStatus(groupPosition, 1); parent.expandGroup(groupPosition); parent.setSelectedGroup(groupPosition); } else if (mAdapter.getGroupClickStatus(groupPosition) == 1) { mAdapter.setGroupClickStatus(groupPosition, 0); parent.collapseGroup(groupPosition); } // 返回 true 才可以弹回第一行 , 不知道为什么 return true; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (mHeaderView != null) { measureChild(mHeaderView, widthMeasureSpec, heightMeasureSpec); mHeaderViewWidth = mHeaderView.getMeasuredWidth(); mHeaderViewHeight = mHeaderView.getMeasuredHeight(); } } private int mOldState = -1; @Override protected void onLayout(boolean changed, int left, int top, int right,int bottom) { super.onLayout(changed, left, top, right, bottom); final long flatPostion = getExpandableListPosition(getFirstVisiblePosition()); final int groupPos = ExpandableListView.getPackedPositionGroup(flatPostion); final int childPos = ExpandableListView.getPackedPositionChild(flatPostion); int state = mAdapter.getQQHeaderState(groupPos, childPos); if (mHeaderView != null && mAdapter != null && state != mOldState) { mOldState = state; mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight); } configureHeaderView(groupPos, childPos); } public void configureHeaderView(int groupPosition, int childPosition) { if (mHeaderView == null || mAdapter == null || ((ExpandableListAdapter) mAdapter).getGroupCount() == 0) { return; } int state = mAdapter.getQQHeaderState(groupPosition, childPosition); switch (state) { case QQHeaderAdapter.PINNED_HEADER_GONE: { mHeaderViewVisible = false; break; } case QQHeaderAdapter.PINNED_HEADER_VISIBLE: { mAdapter.configureQQHeader(mHeaderView, groupPosition,childPosition, MAX_ALPHA); if (mHeaderView.getTop() != 0){ mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight); } mHeaderViewVisible = true; break; } case QQHeaderAdapter.PINNED_HEADER_PUSHED_UP: { View firstView = getChildAt(0); int bottom = firstView.getBottom(); // intitemHeight = firstView.getHeight(); int headerHeight = mHeaderView.getHeight(); int y; int alpha; if (bottom < headerHeight) { y = (bottom - headerHeight); alpha = MAX_ALPHA * (headerHeight + y) / headerHeight; } else { y = 0; alpha = MAX_ALPHA; } mAdapter.configureQQHeader(mHeaderView, groupPosition,childPosition, alpha); if (mHeaderView.getTop() != y) { mHeaderView.layout(0, y, mHeaderViewWidth, mHeaderViewHeight + y); } mHeaderViewVisible = true; break; } } } @Override /** * 列表界面更新时调用该方法(如滚动时) */ protected void dispatchDraw(Canvas canvas) { super.dispatchDraw(canvas); if (mHeaderViewVisible) { //分组栏是直接绘制到界面中，而不是加入到ViewGroup中 drawChild(canvas, mHeaderView, getDrawingT