分析XListView的源码，是因为其他开源控件代码都太多了（主要很多细微的地方都不懂，只能理解个大概），这个控件只是在原生ListView的基础上添加Header和Footer，代码很简单，可以随便折腾。
Github地址：Github上搜索这个就行-----XListView-Android
看Header代码：
/**
* @file XListViewHeader.java
* @create Apr 18, 2012 5:22:27 PM
* @author Maxwin
* @description XListView's header
*/
package me.maxwin.view;
import me.maxwin.R;
import android.content.Context;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.TextView;
public class XListViewHeader extends LinearLayout {
private LinearLayout mContainer;
private ImageView mArrowImageView;
private ProgressBar mProgressBar;
private TextView mHintTextView;
private int mState = STATE_NORMAL;
private Animation mRotateUpAnim;
private Animation mRotateDownAnim;
private final int ROTATE_ANIM_DURATION = 180;
// 正常状态 （箭头不动，进度条隐藏）
public final static int STATE_NORMAL = 0;
// 准备状态 （箭头向上或者向下旋转，进度条隐藏）
public final static int STATE_READY = 1;
// 刷新状态 （箭头隐藏，进度条旋转）
public final static int STATE_REFRESHING = 2;
public XListViewHeader(Context context) {
super(context);
initView(context);
}
/**
* @param context c
* @param attrs a
*/
public XListViewHeader(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
}
/**
* 初始化整个布局：箭头、时间文字、进度条
* 布局宽为FILL_PARENT，Gravity为BOTTOM，这个是为了更新header高度的时候，布局始终在parent的底部
* 箭头的旋转动画
* @param context activity
*/
private void initView(Context context) {
// 初始情况，设置下拉刷新view高度为0
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LayoutParams.MATCH_PARENT, 0);
mContainer = (LinearLayout) LayoutInflater.from(context).inflate(
R.layout.xlistview_header, null);
addView(mContainer, lp);
setGravity(Gravity.BOTTOM);
mArrowImageView = (ImageView)findViewById(R.id.xlistview_header_arrow);
mHintTextView = (TextView)findViewById(R.id.xlistview_header_hint_textview);
mProgressBar = (ProgressBar)findViewById(R.id.xlistview_header_progressbar);
mRotateUpAnim = new RotateAnimation(0.0f, -180.0f,
Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
0.5f);
mRotateUpAnim.setDuration(ROTATE_ANIM_DURATION);
mRotateUpAnim.setFillAfter(true);
mRotateDownAnim = new RotateAnimation(-180.0f, 0.0f,
Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
0.5f);
mRotateDownAnim.setDuration(ROTATE_ANIM_DURATION);
mRotateDownAnim.setFillAfter(true);
}
/**
* 设置刷新的状态：STATE_NORMAL / STATE_READY / STATE_REFRESHING
* 箭头和进度条的隐藏/显示 由上面的if语句判断
* 状态之间的变化由switch语句判断
* @param state state
*/
public void setState(int state) {
// 与之前状态一样，什么都不干
if (state == mState) return ;
/**
* 正在刷新显示进度和文字
* 否则显示箭头和文字
* 也可以按自己需求做成别的样子
*/
if (state == STATE_REFRESHING) { // 显示进度
mArrowImageView.clearAnimation();
mArrowImageView.setVisibility(View.INVISIBLE);
mProgressBar.setVisibility(View.VISIBLE);
} else { // 显示箭头图片
mArrowImageView.setVisibility(View.VISIBLE);
mProgressBar.setVisibility(View.INVISIBLE);
}
switch(state){
case STATE_NORMAL:
/**
* mState 记录的是之前的状态
* 这句代码的意思就是：由STATE_READY变为STATE_NORMAL
* 箭头向下旋转
*/
if (mState == STATE_READY) {
mArrowImageView.startAnimation(mRotateDownAnim);
}
/**
* STATE_REFRESHING 变为 STATE_NORMAL
* 动画清除
*/
if (mState == STATE_REFRESHING) {
mArrowImageView.clearAnimation();
}
mHintTextView.setText(R.string.xlistview_header_hint_normal);
break;
case STATE_READY:
/**
* STATE_REFRESHING 变为 STATE_READY （没有这个状态变化）
* STATE_NORMAL 变为 STATE_READY
* 箭头向上旋转
*/
if (mState != STATE_READY) {
mArrowImageView.clearAnimation();
mArrowImageView.startAnimation(mRotateUpAnim);
mHintTextView.setText(R.string.xlistview_header_hint_ready);
}
break;
case STATE_REFRESHING:
mHintTextView.setText(R.string.xlistview_header_hint_loading);
break;
default:
}
mState = state;
}
/**
* 设置头布局的高度
* @param height h
*/
public void setVisibleHeight(int height) {
if (height < 0)
height = 0;
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) mContainer
.getLayoutParams();
lp.height = height;
mContainer.setLayoutParams(lp);
}
/**
* 获取头布局的高度
* @return h
*/
public int getVisibleHeight() {
return mContainer.getLayoutParams().height;
}
}
看Footer的代码：
/**
* @file XFooterView.java
* @create Mar 31, 2012 9:33:43 PM
* @author Maxwin
* @description XListView's footer
*/
package me.maxwin.view;
import me.maxwin.R;
import android.content.Context;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;
/**
* 上拉加载（显示出footer后，再继续往上拉才会出发上拉加载事件，或者直接点击footer）
* 如果要做自动加载效果，可以自己监听ListView的滑动事件
*/
public class XListViewFooter extends LinearLayout {
public final static int STATE_NORMAL = 0;
public final static int STATE_READY = 1;
public final static int STATE_LOADING = 2;
private Context mContext;
private View mContentView;
private View mProgressBar;
private TextView mHintView;
public XListViewFooter(Context context) {
super(context);
initView(context);
}
public XListViewFooter(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
}
/**
* 设置上拉状态
* @param state s
*/
public void setState(int state) {
mHintView.setVisibility(View.INVISIBLE);
mProgressBar.setVisibility(View.INVISIBLE);
mHintView.setVisibility(View.INVISIBLE);
/**
* STATE_READY：只显示准备文字
* STATE_LOADING：只显示进度条
* STATE_NORMAL：只显示正常文字
* 仍然可以根据自己需要调整
*/
if (state == STATE_READY) {
mHintView.setVisibility(View.VISIBLE);
mHintView.setText(R.string.xlistview_footer_hint_ready);
} else if (state == STATE_LOADING) {
mProgressBar.setVisibility(View.VISIBLE);
} else {
mHintView.setVisibility(View.VISIBLE);
mHintView.setText(R.string.xlistview_footer_hint_normal);
}
}
/**
* 设置footer的margin值
* @param height h
*/
public void setBottomMargin(int height) {
if (height < 0) return ;
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)mContentView.getLayoutParams();
lp.bottomMargin = height;
mContentView.setLayoutParams(lp);
}
/**
* 获取footer的margin值
* @return
*/
public int getBottomMargin() {
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)mContentView.getLayoutParams();
return lp.bottomMargin;
}
/**
* 正常状态
* normal status
*/
public void normal() {
mHintView.setVisibility(View.VISIBLE);
mProgressBar.setVisibility(View.GONE);
}
/**
* 上拉加载状态
* loading status
*/
public void loading() {
mHintView.setVisibility(View.GONE);
mProgressBar.setVisibility(View.VISIBLE);
}
/**
* 隐藏footer，不需要上拉加载的时候
* hide footer when disable pull load more
*/
public void hide() {
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)mContentView.getLayoutParams();
lp.height = 0;
mContentView.setLayoutParams(lp);
}
/**
* 显示footer
* show footer
*/
public void show() {
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)mContentView.getLayoutParams();
lp.height = LayoutParams.WRAP_CONTENT;
mContentView.setLayoutParams(lp);
}
/**
* 初始化footer布局
* @param context activity
*/
private void initView(Context context) {
mContext = context;
LinearLayout moreView = (LinearLayout)LayoutInflater.from(mContext).inflate(R.layout.xlistview_footer, null);
addView(moreView);
moreView.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
mContentView = moreView.findViewById(R.id.xlistview_footer_content);
mProgressBar = moreView.findViewById(R.id.xlistview_footer_progressbar);
mHintView = (TextView)moreView.findViewById(R.id.xlistview_footer_hint_textview);
}
}
看XListView的代码：
/**
* @file XListView.java
* @package me.maxwin.view
* @create Mar 18, 2012 6:28:41 PM
* @author Maxwin
* @description An ListView support (a) Pull down to refresh, (b) Pull up to load more.
* Implement IXListViewListener, and see stopRefresh() / stopLoadMore().
*/
package me.maxwin.view;
import me.maxwin.R;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.animation.DecelerateInterpolator;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.Scroller;
import android.widget.TextView;
public class XListView extends ListView implements OnScrollListener {
private float mLastY = -1; // save event y
private Scroller mScroller; // used for scroll back
private OnScrollListener mScrollListener; // user's scroll listener
// the interface to trigger refresh and load more.
private IXListViewListener mListViewListener;
// -- header view
private XListViewHeader mHeaderView;
// header view content, use it to calculate the Header's height. And hide it
// when disable pull refresh.
private RelativeLayout mHeaderViewContent;
private TextView mHeaderTimeView;
private int mHeaderViewHeight; // header view's height
private boolean mEnablePullRefresh = true;
private boolean mPullRefreshing = false; // is refreashing.
// -- footer view
private XListViewFooter mFooterView;
private boolean mEnablePullLoad;
private boolean mPullLoading;
private boolean mIsFooterReady = false;
// total list items, used to detect is at the bottom of listview.
private int mTotalItemCount;
// for mScroller, scroll back from header or footer.
private int mScrollBack;
private final static int SCROLLBACK_HEADER = 0;
private final static int SCROLLBACK_FOOTER = 1;
private final static int SCROLL_DURATION = 400; // scroll back duration
private final static int PULL_LOAD_MORE_DELTA = 50; // when pull up >= 50px
// at bottom, trigger
// load more.
private final static float OFFSET_RADIO = 1.8f; // support iOS like pull
// feature.
public XListView(Context context) {
super(context);
initWithContext(context);
}
public XListView(Context context, AttributeSet attrs) {
super(context, attrs);
initWithContext(context);
}
public XListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initWithContext(context);
}
/**
* mScroller 用来处理滚动的
* 初始化header，添加header到ListView，获取header的高度
* 初始化footer，不添加到ListView，放在setAdapter里
* @param context activity
*/
private void initWithContext(Context context) {
mScroller = new Scroller(context, new DecelerateInterpolator());
// XListView need the scroll event, and it will dispatch the event to
// user's listener (as a proxy).
super.setOnScrollListener(this);
// init header view
mHeaderView = new XListViewHeader(context);
mHeaderViewContent = (RelativeLayout) mHeaderView
.findViewById(R.id.xlistview_header_content);
mHeaderTimeView = (TextView) mHeaderView
.findViewById(R.id.xlistview_header_time);
addHeaderView(mHeaderView);
// init footer view
mFooterView = new XListViewFooter(context);
// init header height
mHeaderView.getViewTreeObserver().addOnGlobalLayoutListener(
new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
mHeaderViewHeight = mHeaderViewContent.getHeight();
getViewTreeObserver()
.removeGlobalOnLayoutListener(this);
}
});
}
/**
* 先addFooter再setAdapter，避免footer不显示（我遇到过）
* mIsFooterReady是判断footer添加过没有，footer只能添加一次
* @param adapter a
*/
@Override
public void setAdapter(ListAdapter adapter) {
// make sure XListViewFooter is the last footer view, and only add once.
if (mIsFooterReady == false) {
mIsFooterReady = true;
addFooterView(mFooterView);
}
super.setAdapter(adapter);
}
/**
* 设置是否可以下拉刷新
*
* enable or disable pull down refresh feature.
*
* @param enable e
*/
public void setPullRefreshEnable(boolean enable) {
mEnablePullRefresh = enable;
if (!mEnablePullRefresh) { // disable, hide the content
mHeaderViewContent.setVisibility(View.INVISIBLE);
} else {
mHeaderViewContent.setVisibility(View.VISIBLE);
}
}
/**
* 设置是否可以上拉加载
*
* enable or disable pull up load more feature.
*
* @param enable e
*/
public void setPullLoadEnable(boolean enable) {
mEnablePullLoad = enable;
if (!mEnablePullLoad) {
mFooterView.hide();
mFooterView.setOnClickListener(null);
//make sure "pull up" don't show a line in bottom when listview with one page
setFooterDividersEnabled(false);
} else {
mPullLoading = false;
mFooterView.show();
mFooterView.setState(XListViewFooter.STATE_NORMAL);
//make sure "pull up" don't show a line in bottom when listview with one page
setFooterDividersEnabled(true);
// both "pull up" and "click" will invoke load more.
mFooterView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
startLoadMore();
}
});
}
}
/**
* 停止下拉刷新，重置header
* stop refresh, reset header view.
*/
public void stopRefresh() {
if (mPullRefreshing == true) {
mPullRefreshing = false;
resetHeaderHeight();
}
}
/**
* 停止上拉加载，重置footer
* stop load more, reset footer view.
*/
public void stopLoadMore() {
if (mPullLoading == true) {
mPullLoading = false;
mFooterView.setState(XListViewFooter.STATE_NORMAL);
}
}
/**
* 设置上拉刷新的时间
* set last refresh time
*
* @param time
*/
public void setRefreshTime(String time) {
mHeaderTimeView.setText(time);
}
/**
* 触发滑动事件（监听器需要实现OnXScrollListener）
*/
private void invokeOnScrolling() {
if (mScrollListener instanceof OnXScrollListener) {
OnXScrollListener l = (OnXScrollListener) mScrollListener;
l.onXScrolling(this);
}
}
/**
* 更新header的高度
* @param delta 手指拖动的距离
*/
private void updateHeaderHeight(float delta) {
// 更新header的高度 = 之前的高度 + delta
mHeaderView.setVisibleHeight((int) delta
+ mHeaderView.getVisibleHeight());
// 可以下拉刷新，并且不是正在刷新状态
if (mEnablePullRefresh && !mPullRefreshing) { // 未处于刷新状态，更新箭头
/**
* 更新后的高度 > header的初始高度了，状态变为准备状态
* 否则，仍然是普通状态
*/
if (mHeaderView.getVisibleHeight() > mHeaderViewHeight) {
mHeaderView.setState(XListViewHeader.STATE_READY);
} else {
mHeaderView.setState(XListViewHeader.STATE_NORMAL);
}
}
/**
* 这里是没有看懂的地方，为啥子？？？？
*/
setSelection(0); // scroll to top each time
}
/**
* 重置header的高度
* header没有完全显示，什么都不做
* header完全显示了，用mScroller实现滚动（从height到finalHeight - height），header刚好显示
* reset header view's height.
*/
private void resetHeaderHeight() {
int height = mHeaderView.getVisibleHeight();
if (height == 0) // not visible.
return;
// refreshing and header isn't shown fully. do nothing.
if (mPullRefreshing && height <= mHeaderViewHeight) {
return;
}
int finalHeight = 0; // default: scroll back to dismiss header.
// is refreshing, just scroll back to show all the header.
if (mPullRefreshing && height > mHeaderViewHeight) {
finalHeight = mHeaderViewHeight;
}
mScrollBack = SCROLLBACK_HEADER;
mScroller.startScroll(0, height, 0, finalHeight - height,
SCROLL_DURATION);
// trigger computeScroll
invalidate();
}
/**
* 更新footer
* @param delta d
*/
private void updateFooterHeight(float delta) {
int height = mFooterView.getBottomMargin() + (int) delta;
if (mEnablePullLoad && !mPullLoading) {
// 如果footer的margin + 手指拖动的距离 > 限定的距离, 认为触发了上拉加载事件
if (height > PULL_LOAD_MORE_DELTA) { // height enough to invoke load
// more.
mFooterView.setState(XListViewFooter.STATE_READY);
} else {
mFooterView.setState(XListViewFooter.STATE_NORMAL);
}
}
// 更新footer的margin值
mFooterView.setBottomMargin(height);
// setSelection(mTotalItemCount - 1); // scroll to bottom
}
/**
* 重置footer的margin
* 利用mScroller滚动 （从 bottomMargin 到 -bottomMargin）
*/
private void resetFooterHeight() {
int bottomMargin = mFooterView.getBottomMargin();
if (bottomMargin > 0) {
mScrollBack = SCROLLBACK_FOOTER;
mScroller.startScroll(0, bottomMargin, 0, -bottomMargin,
SCROLL_DURATION);
invalidate();
}
}
/**
* 触发上拉加载更多事件，更新footer状态，触发回调
*/
private void startLoadMore() {
mPullLoading = true;
mFooterView.setState(XListViewFooter.STATE_LOADING);
if (mListViewListener != null) {
mListViewListener.onLoadMore();
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (mLastY == -1) {
mLastY = ev.getRawY();
}
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mLastY = ev.getRawY();
break;
case MotionEvent.ACTION_MOVE:
final float deltaY = ev.getRawY() - mLastY;
mLastY = ev.getRawY();
/**
* ListView的第一个item在最顶部，并且手指向下拖动：更新header，触发header滑动监听（onXScrolling）
* ListView的最后一个item在底部，并且手指向上拖动：更新footer
*
*/
if (getFirstVisiblePosition() == 0
&& (mHeaderView.getVisibleHeight() > 0 || deltaY > 0)) {
// the first item is showing, header has shown or pull down.
updateHeaderHeight(deltaY / OFFSET_RADIO);
invokeOnScrolling();
} else if (getLastVisiblePosition() == mTotalItemCount - 1
&& (mFooterView.getBottomMargin() > 0 || deltaY < 0)) {
// last item, already pulled up or want to pull up.
updateFooterHeight(-deltaY / OFFSET_RADIO);
}
break;
default:
/**
* 这里的ev.getAction()应该是：
* UP 和 CANCEL
*/
mLastY = -1; // reset
if (getFirstVisiblePosition() == 0) {
// invoke refresh
/**
* 释放手指的之后，header的高度 > 最原本的高度，触发下拉刷新事件
* 更新状态，并回调
* 最后重置高度
*/
if (mEnablePullRefresh
&& mHeaderView.getVisibleHeight() > mHeaderViewHeight) {
mPullRefreshing = true;
mHeaderView.setState(XListViewHeader.STATE_REFRESHING);
if (mListViewListener != null) {
mListViewListener.onRefresh();
}
}
resetHeaderHeight();
} else if (getLastVisiblePosition() == mTotalItemCount - 1) {
// invoke load more.
/**
* 释放手指之后，footer的margin > 限定的距离
* 触发上拉加载事件，并回调
* 最后重置高度
*/
if (mEnablePullLoad
&& mFooterView.getBottomMargin() > PULL_LOAD_MORE_DELTA
&& !mPullLoading) {
startLoadMore();
}
resetFooterHeight();
}
break;
}
return super.onTouchEvent(ev);
}
/**
* mScroll 实现滚动必须要覆盖的方法
*/
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
if (mScrollBack == SCROLLBACK_HEADER) {
mHeaderView.setVisibleHeight(mScroller.getCurrY());
} else {
mFooterView.setBottomMargin(mScroller.getCurrY());
}
postInvalidate();
invokeOnScrolling();
}
super.computeScroll();
}
@Override
public void setOnScrollListener(OnScrollListener l) {
mScrollListener = l;
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (mScrollListener != null) {
mScrollListener.onScrollStateChanged(view, scrollState);
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// send to user's listener
mTotalItemCount = totalItemCount;
if (mScrollListener != null) {
mScrollListener.onScroll(view, firstVisibleItem, visibleItemCount,
totalItemCount);
}
}
public void setXListViewListener(IXListViewListener l) {
mListViewListener = l;
}
/**
* you can listen ListView.OnScrollListener or this one. it will invoke
* onXScrolling when header/footer scroll back.
*/
public interface OnXScrollListener extends OnScrollListener {
public void onXScrolling(View view);
}
/**
* implements this interface to get refresh/load more event.
*/
public interface IXListViewListener {
public void onRefresh();
public void onLoadMore();
}
}
结束，很简单啊。