在2月27号的时候，完成listView滑动刷新代码，昨天的时候，完成listView下拉刷新(sina微博Android客户端效果)效果的解析，其实在三个例子当中，感觉最好的应该是listView下拉刷新(sina微博Android客户端效果)里面的代码，今天进行第三个例子的解析，其中代码中添加了很多注释，所以文中代码和以前上传的代码注释方面会有很多不同，在文章的下面，会提供最新的代码下载。
看这个代码的时候，刚开始一直是没有弄明白是怎么样运行的，后来通过不断的打log，大概弄了个明白，先给大家看下log:
在下面，会把log语句的具体含义简单的说明一下。
然后再把代码贴出来，按照log，一步一步跟踪，看它的实现过程：
public boolean onTouchEvent(MotionEvent event) {
if (isRefreshable) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (firstItemIndex == 0 && !isRecored) {
isRecored = true;
startY = (int) event.getY();
Log.v("@@@@@@", "ACTION_DOWN 这是第"+i+++"步" +1 );
}
break;
case MotionEvent.ACTION_UP:
if (state != REFRESHING && state != LOADING) {
if (state == DONE) {
}
if (state == PULL_To_REFRESH) {
state = DONE;
Log.v("@@@@@@", "ACTION_UP PULL_To_REFRESH and changeHeaderViewByState()" +
" 这是第"+i+++"步前"+2 );
changeHeaderViewByState();
Log.v("@@@@@@", "ACTION_UP PULL_To_REFRESH and changeHeaderViewByState() " +
"这是第"+i+++"步后"+2 );
}
if (state == RELEASE_To_REFRESH) {
state = REFRESHING;
Log.v("@@@@@@", "ACTION_UP RELEASE_To_REFRESH changeHeaderViewByState() " +
"这是第"+i+++"步" +3);
changeHeaderViewByState();
onRefresh();
Log.v("@@@@@@", "ACTION_UP RELEASE_To_REFRESH changeHeaderViewByState()" +
" 这是第"+i+++"步" +3);
}
}
isRecored = false;
isBack = false;
break;
case MotionEvent.ACTION_MOVE:
int tempY = (int) event.getY();
if (!isRecored && firstItemIndex == 0) {
isRecored = true;
startY = tempY;
Log.v("@@@@@@", "ACTION_MOVE 这是第"+i+++"步" +4);
}
if (state != REFRESHING && isRecored && state != LOADING) {
if (state == RELEASE_To_REFRESH) {
setSelection(0);
if (((tempY - startY) / RATIO < headContentHeight)
&& (tempY - startY) > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
Log.v("@@@@@@", "changeHeaderViewByState() 这是第"+i+++"步"+5 );
}
else if (tempY - startY <= 0) {
state = DONE;
changeHeaderViewByState();
Log.v("@@@@@@", "ACTION_MOVE RELEASE_To_REFRESH 2changeHeaderViewByState " +
"这是第"+i+++"步" +6);
}
}
if (state == PULL_To_REFRESH) {
setSelection(0);
if ((tempY - startY) / RATIO >= headContentHeight) {
state = RELEASE_To_REFRESH;
isBack = true;
Log.v("@@@@@@", "changeHeaderViewByState " +
"这是第"+i+++"步前"+7 );
changeHeaderViewByState();
Log.v("@@@@@@", "changeHeaderViewByState " +
"这是第"+i+++"步后"+7 );
}
else if (tempY - startY <= 0) {
state = DONE;
changeHeaderViewByState();
Log.v("@@@@@@", "ACTION_MOVE changeHeaderViewByState PULL_To_REFRESH 2" +
" 这是第"+i+++"步" +8);
}
}
if (state == DONE) {
if (tempY - startY > 0) {
state = PULL_To_REFRESH;
Log.v("@@@@@@", "ACTION_MOVE DONE changeHeaderViewByState " +
"这是第"+i+++"步前" +9);
changeHeaderViewByState();
Log.v("@@@@@@", "ACTION_MOVE DONE changeHeaderViewByState " +
"这是第"+i+++"步后" +9);
}
}
if (state == PULL_To_REFRESH) {
headView.setPadding(0, -1 * headContentHeight+(tempY - startY) / RATIO, 0, 0);
Log.v("@@@@@@", -1 * headContentHeight+(tempY - startY) / RATIO+
"ACTION_MOVE PULL_To_REFRESH 3这是第"+i+++"步"+10 );
}
if (state == RELEASE_To_REFRESH) {
headView.setPadding(0, (tempY - startY) / RATIO- headContentHeight, 0, 0);
Log.v("@@@@@@", "ACTION_MOVE PULL_To_REFRESH 4 这是第"+i+++"步" +11);
}
}
break;
}
}
return super.onTouchEvent(event);
}
private void changeHeaderViewByState() {
switch (state) {
case RELEASE_To_REFRESH:
arrowImageView.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.startAnimation(animation);
tipsTextview.setText("请释放 刷新");
Log.v("@@@@@@", "RELEASE_To_REFRESH 这是第"+i+++"步"+12 +"请释放 刷新" );
break;
case PULL_To_REFRESH:
progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.VISIBLE);
if (isBack) {
isBack = false;
arrowImageView.clearAnimation();
arrowImageView.startAnimation(reverseAnimation);
tipsTextview.setText("isBackis true ！！！");
} else {
tipsTextview.setText("isBackis false ！！！");
}
Log.v("@@@@@@", "PULL_To_REFRESH 这是第"+i+++"步" +13+
"changeHeaderViewByState()");
break;
case REFRESHING:
headView.setPadding(0, 0, 0, 0);
progressBar.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.GONE);
tipsTextview.setText("正在加载中 ...REFRESHING");
lastUpdatedTextView.setVisibility(View.VISIBLE);
Log.v("@@@@@@", "REFRESHING 这是第"+i+++"步" +"正在加载中 ...REFRESHING");
break;
case DONE:
headView.setPadding(0, -1 * headContentHeight, 0, 0);
progressBar.setVisibility(View.GONE);
arrowImageView.clearAnimation();
arrowImageView.setImageResource(R.drawable.arrow);
tipsTextview.setText("已经加载完毕- DONE ");
lastUpdatedTextView.setVisibility(View.VISIBLE);
Log.v("@@@@@@", "DONE 这是第"+i+++"步" +"已经加载完毕- DONE ");
break;
}
}
以上就是 主要的功能代码，这个功能的实现，并没有在重写onScroll和onScrollStateChanged两个方法：
public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2,
int arg3) {
firstItemIndex = firstVisiableItem;
}
public void onScrollStateChanged(AbsListView arg0, int arg1) {
}
主要就是通过onTouchEvent方法中根据不同的状态，进行不同的变化。
先看下各个状态的定义：
//释放刷新
private final static int RELEASE_To_REFRESH = 0;
//下拉刷新
private final static int PULL_To_REFRESH = 1;
//正在刷新
private final static int REFRESHING = 2;
//刷新完成
private final static int DONE = 3;
下面就开始通过log，跟踪代码的执行过程，首先执行的肯定是onTouchEvent里面的ACTION_DOWN
if (firstItemIndex == 0 && !isRecored) {
isRecored = true;
startY = (int) event.getY();
Log.v("@@@@@@", "ACTION_DOWN 这是第"+i+++"步" +1 );
}
break;
在这里，简单的说明下，log语句的意思，这是第"+i+++"步"，是说明这是进行的第几步，最后面跟的数字是为了独特的标记该log。
再往下看：
我们在log中找到9，然后看一下，在ACTION_MOVE中，执行了这一步：
if (state == DONE) {
if (tempY - startY > 0) {
state = PULL_To_REFRESH;
Log.v("@@@@@@", "ACTION_MOVE DONE changeHeaderViewByState " +
"这是第"+i+++"步前" +9);
changeHeaderViewByState();
Log.v("@@@@@@", "ACTION_MOVE DONE changeHeaderViewByState " +
"这是第"+i+++"步后" +9);
}
}
为什么呢？因为在初始化的时候，把state初始化为Done，然后，
state = PULL_To_REFRESH;
changeHeaderViewByState();
把state状态转换为PULL_To_REFRESH，然后运行changeHeaderViewByState方法里面
case PULL_To_REFRESH:
progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.VISIBLE);
if (isBack) {
isBack = false;
arrowImageView.clearAnimation();
arrowImageView.startAnimation(reverseAnimation);
tipsTextview.setText("isBackis true ！！！");
} else {
tipsTextview.setText("isBackis false ！！！");
}
Log.v("@@@@@@", "PULL_To_REFRESH 这是第"+i+++"步" +13+
"changeHeaderViewByState()");
break;
在这里的各个控件的状态变化。state状态转换为PULL_To_REFRESH，代码继续向下进行
所以会执行以下代码：
if (state == PULL_To_REFRESH) {
headView.setPadding(0, -1 * headContentHeight+(tempY - startY) / RATIO, 0, 0);
Log.v("@@@@@@", -1 * headContentHeight+(tempY - startY) / RATIO+
"ACTION_MOVE PULL_To_REFRESH 3这是第"+i+++"步"+10 );
}
设置headView的各个距离，随后break，但是返回以后呢？还是继续进行ACTION_MOVE，由于state状态转换为PULL_To_REFRESH，所以会执行：
if (state == PULL_To_REFRESH) {
setSelection(0);
if ((tempY - startY) / RATIO >= headContentHeight) {
state = RELEASE_To_REFRESH;
isBack = true;
Log.v("@@@@@@", "changeHeaderViewByState " +
"这是第"+i+++"步前"+7 );
changeHeaderViewByState();
Log.v("@@@@@@", "changeHeaderViewByState " +
"这是第"+i+++"步后"+7 );
}
else if (tempY - startY <= 0) {
state = DONE;
changeHeaderViewByState();
Log.v("@@@@@@", "ACTION_MOVE changeHeaderViewByState PULL_To_REFRESH 2" +
" 这是第"+i+++"步" +8);
}
}
在本log里走的是if的第一分支，把state 的状态转化为RELEASE_To_REFRESH，然后执行changeHeaderViewByState里面：
case RELEASE_To_REFRESH:
arrowImageView.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.startAnimation(animation);
tipsTextview.setText("请释放 刷新");
Log.v("@@@@@@", "RELEASE_To_REFRESH 这是第"+i+++"步"+12 +"请释放 刷新" );
break;
如果继续向下拉，会执行ACTION_MOVE中的：
if (state == RELEASE_To_REFRESH) {
headView.setPadding(0, (tempY - startY) / RATIO- headContentHeight, 0, 0);
Log.v("@@@@@@", "ACTION_MOVE PULL_To_REFRESH 4 这是第"+i+++"步" +11);
}
继续看log：
进行完两个11以后，又会执行哪些代码呢？我们看到了3，然后我们找下这个log.
case MotionEvent.ACTION_UP:
if (state != REFRESHING && state != LOADING) {
if (state == DONE) {
}
if (state == PULL_To_REFRESH) {
state = DONE;
Log.v("@@@@@@", "ACTION_UP PULL_To_REFRESH and changeHeaderViewByState()" +
" 这是第"+i+++"步前"+2 );
changeHeaderViewByState();
Log.v("@@@@@@", "ACTION_UP PULL_To_REFRESH and changeHeaderViewByState() " +
"这是第"+i+++"步后"+2 );
}
if (state == RELEASE_To_REFRESH) {
state = REFRESHING;
Log.v("@@@@@@", "ACTION_UP RELEASE_To_REFRESH changeHeaderViewByState() " +
"这是第"+i+++"步" +3);
changeHeaderViewByState();
onRefresh();
Log.v("@@@@@@", "ACTION_UP RELEASE_To_REFRESH changeHeaderViewByState()" +
" 这是第"+i+++"步" +3);
}
}
isRecored = false;
isBack = false;
break;
就是当手指送开的时候，执行到了ACTION_UP，因为state 的状态转化为RELEASE_To_REFRESH，里面调用了
case RELEASE_To_REFRESH:
arrowImageView.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.startAnimation(animation);
tipsTextview.setText("请释放 刷新");
Log.v("@@@@@@", "RELEASE_To_REFRESH 这是第"+i+++"步"+12 +"请释放 刷新" );
break;
和onRefresh方法，和listView下拉刷新(sina微博Android客户端效果)一样，这是个回调方法。
最后调用 onRefreshComplete刷新完成方法：
public void onRefreshComplete() {
state = DONE;
lastUpdatedTextView.setText("已加载完成: " + new Date().toLocaleString());
changeHeaderViewByState();
Log.v("@@@@@@", "onRefreshComplete() 被调用。。。");
}
最后程序运行结果如下：
下拉
继续下拉
手指松开
