6.下拉刷新
下拉刷新-------
1.addHeaderView必须在setAdapter之前调用
2.将paddingTop设置一个headerView高度的负值去隐藏它
getHeight()和getMeasuredHeight()的区别：
getMeasuredHeight():获取测量完的高度，只要在onMeasure方法执行完，就可以用
它获取到宽高，在自定义控件内部多使用这个
使用view.measure(0,0)方法可以主动通知系统去测量，然后就
可以直接使用它获取宽高
getHeight()：必须在onLayout方法执行完后，才能获得宽高
view.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
headerView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
int headerViewHeight = headerView.getHeight();//直接可以获取宽高
}
});
3.setSelection(position);将对应位置的item放置到屏幕顶端
RefreshListView
public class RefreshListView extends ListView implements OnScrollListener{
private View headerView;//headerView
private ImageView iv_arrow;
private ProgressBar pb_rotate;
private TextView tv_state,tv_time;
private View footerView;
private int footerViewHeight;
private int headerViewHeight;//headerView高
private int downY;//按下时y坐标
private final int PULL_REFRESH = 0;//下拉刷新的状态
private final int RELEASE_REFRESH = 1;//松开刷新的状态
private final int REFRESHING = 2;//正在刷新的状态
private int currentState = PULL_REFRESH;
private RotateAnimation upAnimation,downAnimation;
private boolean isLoadingMore = false;//当前是否正在处于加载更多
public RefreshListView(Context context) {
super(context);
init();
}
public RefreshListView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init(){
setOnScrollListener(this);
initHeaderView();
initRotateAnimation();
initFooterView();
}
/**
* 初始化headerView
*/
private void initHeaderView() {
headerView = View.inflate(getContext(), R.layout.layout_header, null);
iv_arrow = (ImageView) headerView.findViewById(R.id.iv_arrow);
pb_rotate = (ProgressBar) headerView.findViewById(R.id.pb_rotate);
tv_state = (TextView) headerView.findViewById(R.id.tv_state);
tv_time = (TextView) headerView.findViewById(R.id.tv_time);
headerView.measure(0, 0);//主动通知系统去测量该view;
headerViewHeight = headerView.getMeasuredHeight();
headerView.setPadding(0, -headerViewHeight, 0, 0);
addHeaderView(headerView);
}
/**
* 初始化旋转动画
*/
private void initRotateAnimation() {
upAnimation = new RotateAnimation(0, -180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
upAnimation.setDuration(300);
upAnimation.setFillAfter(true);
downAnimation = new RotateAnimation(-180, -360,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
downAnimation.setDuration(300);
downAnimation.setFillAfter(true);
}
private void initFooterView() {
footerView = View.inflate(getContext(), R.layout.layout_footer, null);
footerView.measure(0, 0);//主动通知系统去测量该view;
footerViewHeight = footerView.getMeasuredHeight();
footerView.setPadding(0, -footerViewHeight, 0, 0);
addFooterView(footerView);
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
downY = (int) ev.getY();
break;
case MotionEvent.ACTION_MOVE:
if(currentState==REFRESHING){
break;
}
int deltaY = (int) (ev.getY() - downY);
int paddingTop = -headerViewHeight + deltaY;
if(paddingTop>-headerViewHeight && getFirstVisiblePosition()==0){
headerView.setPadding(0, paddingTop, 0, 0);
// Log.e("RefreshListView", "paddingTop: "+paddingTop);
if(paddingTop>=0 && currentState==PULL_REFRESH){
//从下拉刷新进入松开刷新状态
currentState = RELEASE_REFRESH;
refreshHeaderView();
}else if (paddingTop<0 && currentState==RELEASE_REFRESH) {
//进入下拉刷新状态
currentState = PULL_REFRESH;
refreshHeaderView();
}
return true;//拦截TouchMove，不让listview处理该次move事件,会造成listview无法滑动
}
break;
case MotionEvent.ACTION_UP:
if(currentState==PULL_REFRESH){
//隐藏headerView
headerView.setPadding(0, -headerViewHeight, 0, 0);
}else if (currentState==RELEASE_REFRESH) {
headerView.setPadding(0, 0, 0, 0);
currentState = REFRESHING;
refreshHeaderView();
if(listener!=null){
listener.onPullRefresh();
}
}
break;
}
return super.onTouchEvent(ev);
}
/**
* 根据currentState来更新headerView
*/
private void refreshHeaderView(){
switch (currentState) {
case PULL_REFRESH:
tv_state.setText("下拉刷新");
iv_arrow.startAnimation(downAnimation);
break;
case RELEASE_REFRESH:
tv_state.setText("松开刷新");
iv_arrow.startAnimation(upAnimation);
break;
case REFRESHING:
iv_arrow.clearAnimation();//因为向上的旋转动画有可能没有执行完
iv_arrow.setVisibility(View.INVISIBLE);
pb_rotate.setVisibility(View.VISIBLE);
tv_state.setText("正在刷新...");
break;
}
}
/**
* 完成刷新操作，重置状态,在你获取完数据并更新完adater之后，去在UI线程中调用该方法
*/
public void completeRefresh(){
if(isLoadingMore){
//重置footerView状态
footerView.setPadding(0, -footerViewHeight, 0, 0);
isLoadingMore = false;
}else {
//重置headerView状态
headerView.setPadding(0, -headerViewHeight, 0, 0);
currentState = PULL_REFRESH;
pb_rotate.setVisibility(View.INVISIBLE);
iv_arrow.setVisibility(View.VISIBLE);
tv_state.setText("下拉刷新");
tv_time.setText("最后刷新："+getCurrentTime());
}
}
/**
* 获取当前系统时间，并格式化
* @return
*/
private String getCurrentTime(){
SimpleDateFormat format = new SimpleDateFormat("yy-MM-dd HH:mm:ss");
return format.format(new Date());
}
private OnRefreshListener listener;
public void setOnRefreshListener(OnRefreshListener listener){
this.listener = listener;
}
public interface OnRefreshListener{
void onPullRefresh();
void onLoadingMore();
}
/**
* SCROLL_STATE_IDLE:闲置状态，就是手指松开
* SCROLL_STATE_TOUCH_SCROLL：手指触摸滑动，就是按着来滑动
* SCROLL_STATE_FLING：快速滑动后松开
*/
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if(scrollState==OnScrollListener.SCROLL_STATE_IDLE
&& getLastVisiblePosition()==(getCount()-1) &&!isLoadingMore){
isLoadingMore = true;
footerView.setPadding(0, 0, 0, 0);//显示出footerView
setSelection(getCount());//让listview最后一条显示出来
if(listener!=null){
listener.onLoadingMore();
}
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
}
}
MainActivity
public class MainActivity extends Activity {
private RefreshListView refreshListView;
private ArrayList<String> list = new ArrayList<String>();
private MyAdapter adapter;
private Handler handler = new Handler(){
public void handleMessage(android.os.Message msg) {
//更新UI
adapter.notifyDataSetChanged();
refreshListView.completeRefresh();
};
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initView();
initData();
}
private void initView() {
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
refreshListView = (RefreshListView) findViewById(R.id.refreshListView);
}
private void initData() {
for (int i = 0; i < 15; i++) {
list.add("listview原来的数据 - "+i);
}
// final View headerView = View.inflate(this, R.layout.layout_header, null);
//第一种方法
// headerView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
// @Override
// public void onGlobalLayout() {
// headerView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
// int headerViewHeight = headerView.getHeight();
//
//
// Log.e("MainActivity", "headerViewHeight: "+headerViewHeight);
// headerView.setPadding(0, -headerViewHeight, 0, 0);
// refreshListView.addHeaderView(headerView);//
// }
// });
//第二种方法
// headerView.measure(0, 0);//主动通知系统去测量
// int headerViewHeight = headerView.getMeasuredHeight();
// Log.e("MainActivity", "headerViewHeight: "+headerViewHeight);
// headerView.setPadding(0, -headerViewHeight, 0, 0);
// refreshListView.addHeaderView(headerView);//
adapter = new MyAdapter();
refreshListView.setAdapter(adapter);
refreshListView.setOnRefreshListener(new OnRefreshListener() {
@Override
public void onPullRefresh() {
//需要联网请求服务器的数据，然后更新UI
requestDataFromServer(false);
}
@Override
public void onLoadingMore() {
requestDataFromServer(true);
}
});
}
/**
* 模拟向服务器请求数据
*/
private void requestDataFromServer(final boolean isLoadingMore){
new Thread(){
public void run() {
SystemClock.sleep(3000);//模拟请求服务器的一个时间长度
if(isLoadingMore){
list.add("加载更多的数据-1");
list.add("加载更多的数据-2");
list.add("加载更多的数据-3");
}else {
list.add(0, "下拉刷新的数据");
}
//在UI线程更新UI
handler.sendEmptyMessage(0);
};
}.start();
}
class MyAdapter extends BaseAdapter{
@Override
public int getCount() {
return list.size();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
TextView textView = new TextView(MainActivity.this);
textView.setPadding(20, 20, 20, 20);
textView.setTextSize(18);
textView.setText(list.get(position));
return textView;
}
}
}
