listView下拉刷新加载数据
来源:互联网 发布:淘宝企业店铺转个人 编辑:程序博客网 时间:2024/05/01 22:24
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 2 changeHeaderViewByState " +
- "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("isBack is true !!!");
- } else {
- tipsTextview.setText("isBack is 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);
- }
- }
- state = PULL_To_REFRESH;
- changeHeaderViewByState();
- 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("isBack is true !!!");
- } else {
- tipsTextview.setText("isBack is 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
- listView下拉刷新加载数据
- listView下拉刷新加载数据
- listview 下拉刷新加载数据
- listView下拉刷新加载数据
- listView下拉刷新加载数据详解
- ListView下拉刷新加载
- 自定义ListView 实现上拉刷新 下拉加载数据
- PullToRefresh 上拉刷新,下拉加载网络数据 ListView
- listview下拉刷新 滚动加载
- ListView 下拉刷新 加载更多
- Android Listview下拉刷新数据
- PullToRefreshListView上拉加载,下拉刷新 刷新网络数据 简单实现ListView显示网络数据
- 超级ListView,包括下拉刷新,自动翻页加载数据,异步下载、加载图片缓存等
- 一步一步实现ListView加载网络数据,下滑底部加载,顶部下拉刷新。并配有双缓存
- listView上拉刷新下拉加载
- Listview 下拉刷新,上拉加载更多
- Android ListView 下拉刷新 上拉加载
- Android ListView 下拉刷新 点击加载更多
- Android Bitmap 与 Drawable之间的转换
- listView下拉刷新(仿sina微博Android客户端效果)
- ashx灵活处理文件下载问题
- UVa 10047 - The Monocycle, 优先队列+BFS
- 天平称球问题(一)
- listView下拉刷新加载数据
- listView滑动刷新代码(分页功能)
- 关于一个 date-time 时间服务的daemon process 的代码实现
- 通过进程ID获取进程主窗口句柄
- 关于session超时、网址里有未知字符的问题
- extjs的treepanel不自动加载的实现
- XMPP协议分析-原理篇
- 程序设计名词解释
- DLL远程注入代码