下拉刷新Demo[通俗易懂]

大家好，又见面了，我是你们的朋友全栈君。如果您正在找激活码,请点击查看最新教程,关注关注公众号 “全栈程序员社区” 获取激活教程,可能之前旧版本教程已经失效.最新Idea2022.1教程亲测有效,一键激活。

Jetbrains全家桶1年46，售后保障稳定

引用了网上的demo。总结下使用，方便以后简单使用。

/**
* 下拉刷新
*/
public class RefreshListView extends ListView implements OnScrollListener {
private static final String TAG = "am10";
private final static int RELEASE_To_REFRESH = 0;
private final static int PULL_To_REFRESH = 1;
private final static int REFRESHING = 2;
private final static int DONE = 3;
private final static int LOADING = 4;
// 实际的padding的距离与界面上偏移距离的比例
private final static int RATIO = 2;
private LayoutInflater inflater;
private LinearLayout headView;
private TextView tipsTextview;
private TextView lastUpdatedTextView;
private ImageView arrowImageView;
// private ProgressBar progressBar;
private RotateAnimation animation;
private RotateAnimation reverseAnimation;
// 用于保证startY的值在一个完整的touch事件中只被记录一次
private boolean isRecored;
private int startY;
private int firstItemIndex;
private int headContentWidth;
private int headContentHeight;
private int state;
private boolean isBack;
private OnRefreshListener refreshListener;
private boolean isRefreshable;
public RefreshListView(Context context) {
super(context);
init(context);
}
public RefreshListView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
private void init(Context context) {
// setCacheColorHint(context.getResources().getColor(R.color.transparent));
inflater = LayoutInflater.from(context);
headView = (LinearLayout) inflater.inflate(R.layout.header, null);
arrowImageView = (ImageView) headView
.findViewById(R.id.xlistview_header_arrow);
arrowImageView.setMinimumWidth(70);
arrowImageView.setMinimumHeight(50);
// progressBar = (ProgressBar)
// headView.findViewById(R.id.head_progressBar);
tipsTextview = (TextView) headView
.findViewById(R.id.xlistview_header_hint_textview);
lastUpdatedTextView = (TextView) headView
.findViewById(R.id.xlistview_header_time);
// 估算headView的宽和高
measureView(headView);
headContentHeight = headView.getMeasuredHeight();
headContentWidth = headView.getMeasuredWidth();
headView.setPadding(0, -1 * headContentHeight, 0, 0);
headView.invalidate();
Log.v(TAG, "width:" + headContentWidth + " height:" + headContentHeight);
addHeaderView(headView, null, false);
setOnScrollListener(this);
/**
* 刷新的 旋转动画，使得字体颠倒
*/
animation = new RotateAnimation(0, -180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
animation.setInterpolator(new LinearInterpolator());
animation.setDuration(250);
animation.setFillAfter(true);
reverseAnimation = new RotateAnimation(-180, 0,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
reverseAnimation.setInterpolator(new LinearInterpolator());
reverseAnimation.setDuration(200);
reverseAnimation.setFillAfter(true);
state = DONE;
isRefreshable = false;
}
public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2,
int arg3) {
firstItemIndex = firstVisiableItem;
// Log.v(TAG, "firstItemIndex: "+firstItemIndex);
}
public void onScrollStateChanged(AbsListView arg0, int arg1) {
}
/**
* 触摸屏幕的事件
*/
public boolean onTouchEvent(MotionEvent event) {
// Log.v(TAG, "isRefreshable: "+isRefreshable);
if (isRefreshable) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (firstItemIndex == 0 && !isRecored) {
isRecored = true;
// 触摸屏幕的位置
startY = (int) event.getY();
Log.v(TAG, "在down时候记录当前位置" + " startY:" + startY);
}
break;
case MotionEvent.ACTION_UP:
if (state != REFRESHING && state != LOADING) {
if (state == DONE) {
// 什么都不做
}
if (state == PULL_To_REFRESH) {
state = DONE;
changeHeaderViewByState();
Log.v(TAG, "由下拉刷新状态，到done状态");
}
if (state == RELEASE_To_REFRESH) {
state = REFRESHING;
changeHeaderViewByState();
onRefresh();
Log.v(TAG, "由松开刷新状态，到done状态");
}
}
isRecored = false;
isBack = false;
break;
case MotionEvent.ACTION_MOVE:
// 获取手势位置
int tempY = (int) event.getY();
// Log.v(TAG, "tempY: " + tempY);
/**
* 手指移动过程中tempY数据会不断变化,当滑动到firstItemIndex,即到达顶部, 需要记录手指所在屏幕的位置:
* startY = tempY ,后面作位置比较使用
* 
* 如果手指继续向下推,tempY继续变化,当tempY-startY>0,即是需要显示header部分
* 
* 此时需要更改状态：state = PULL_To_REFRESH
*/
if (!isRecored && firstItemIndex == 0) {
isRecored = true;
startY = tempY;
Log.v(TAG, "在move时候记录下位置" + " startY:" + startY);
}
if (state != REFRESHING && isRecored && state != LOADING) {
/**
* 保证在设置padding的过程中，当前的位置一直是在head，
* 否则如果当列表超出屏幕的话，当在上推的时候，列表会同时进行滚动
*/
// 可以松手去刷新了
if (state == RELEASE_To_REFRESH) {
setSelection(0);
// 往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步
if (((tempY - startY) / RATIO < headContentHeight)
&& (tempY - startY) > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
Log.v(TAG, "由松开刷新状态转变到下拉刷新状态");
}
// 一下子推到顶了,没有显示header部分时,应该恢复DONE状态,这里机率很小
else if (tempY - startY <= 0) {
state = DONE;
changeHeaderViewByState();
Log.v(TAG, "---由松开刷新状态转变到done状态");
} else {
// 往下拉了，或者还没有上推到屏幕顶部掩盖head的地步
// 不用进行特别的操作，只用更新paddingTop的值就行了
}
}
// 还没有到达显示松开刷新的时候,DONE或者是PULL_To_REFRESH状态
if (state == PULL_To_REFRESH) {
setSelection(0);
/**
* 下拉到可以进入RELEASE_TO_REFRESH的状态
* 
* 等于headContentHeight时,即是正好完全显示header部分
* 大于headContentHeight时,即是超出header部分更多
* 
* 当header部分能够完全显示或者超出显示, 需要更改状态: state =
* RELEASE_To_REFRESH
*/
if ((tempY - startY) / RATIO >= headContentHeight) {
state = RELEASE_To_REFRESH;
isBack = true;
changeHeaderViewByState();
Log.v(TAG, "由done或者下拉刷新状态转变到松开刷新");
}
// 上推到顶了,没有显示header部分时,应该恢复DONE状态
else if (tempY - startY <= 0) {
state = DONE;
changeHeaderViewByState();
Log.v(TAG, "由done或者下拉刷新状态转变到done状态");
}
}
// done状态下
if (state == DONE) {
if (tempY - startY > 0) {
/**
* 手指移动过程中tempY数据会不断变化,当滑动到firstItemIndex,即到达顶部,
* 需要记录手指所在屏幕的位置: startY = tempY ,后面作位置比较使用
* 
* 如果手指继续向下推,tempY继续变化,当tempY-startY>0,
* 即是需要显示header部分
* 
* 此时需要更改状态：state = PULL_To_REFRESH
*/
// Log.v(TAG, "----------------PULL_To_REFRESH " +
// (tempY - startY));
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
}
/**
* ********** 更新headView的paddingTop ************
* 根据不同的top值来设置组件的位置
*/
if (state == PULL_To_REFRESH) {
// Log.v(TAG, "----------------PULL_To_REFRESH2 " +
// (tempY - startY));
// headView.setPadding(0, -1 * headContentHeight
// + (tempY - startY) / RATIO, 0, 0);
headView.setPadding(0, -1 * headContentHeight
+ (tempY - startY) / RATIO, 0, 0);
}
/**
* 继续更新headView的paddingTop
*/
if (state == RELEASE_To_REFRESH) {
headView.setPadding(0, (tempY - startY) / RATIO
- headContentHeight, 0, 0);
}
}
break;
}
}
return super.onTouchEvent(event);
}
// 当状态改变时候，调用该方法，以更新界面
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("松开刷新");
Log.v(TAG, "当前状态，松开刷新");
break;
case PULL_To_REFRESH:
// progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.VISIBLE);
/**
* 是否向下滑回，是由RELEASE_To_REFRESH状态转变来的
*/
if (isBack) {
isBack = false;
arrowImageView.clearAnimation();
arrowImageView.startAnimation(reverseAnimation);
tipsTextview.setText("下拉刷新");
// Log.v(TAG, "isBack: " + isBack);
} else {
tipsTextview.setText("下拉刷新");
// Log.v(TAG, "isBack: " + isBack);
}
Log.v(TAG, "当前状态，下拉刷新");
break;
case REFRESHING:
Log.v(TAG, "REFRESHING...");
headView.setPadding(0, 0, 0, 0);
// progressBar.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.GONE);
tipsTextview.setText("正在刷新...");
lastUpdatedTextView.setVisibility(View.VISIBLE);
Log.v(TAG, "当前状态,正在刷新...");
break;
case DONE:
headView.setPadding(0, -1 * headContentHeight, 0, 0);
// progressBar.setVisibility(View.GONE);
arrowImageView.clearAnimation();
/**
* 第二次下拉的时候，调用该方法
*/
// arrowImageView.setImageResource(R.drawable.refresh);
tipsTextview.setText("下拉刷新");
lastUpdatedTextView.setVisibility(View.VISIBLE);
Log.v(TAG, "当前状态，done");
break;
}
}
public void setOnRefreshListener(OnRefreshListener refreshListener) {
this.refreshListener = refreshListener;
isRefreshable = true;
}
public interface OnRefreshListener {
public void onRefresh();
}
public void onRefreshComplete() {
state = DONE;
SimpleDateFormat format = new SimpleDateFormat("yyyy年MM月dd日  HH:mm");
String date = format.format(new Date());
lastUpdatedTextView.setText("最近更新:" + date);
changeHeaderViewByState();
}
private void onRefresh() {
if (refreshListener != null) {
refreshListener.onRefresh();
}
}
// 此方法直接照搬自网络上的一个下拉刷新的demo，此处是“估计”headView的width以及height
private void measureView(View child) {
ViewGroup.LayoutParams p = child.getLayoutParams();
if (p == null) {
// Log.v(TAG, "LayoutParams is null.");
p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width);
int lpHeight = p.height;
int childHeightSpec;
if (lpHeight > 0) {
childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,
MeasureSpec.EXACTLY);
} else {
childHeightSpec = MeasureSpec.makeMeasureSpec(0,
MeasureSpec.UNSPECIFIED);
}
child.measure(childWidthSpec, childHeightSpec);
}
public void setAdapter(BaseAdapter adapter) {
SimpleDateFormat format = new SimpleDateFormat("yyyy年MM月dd日  HH:mm");
String date = format.format(new Date());
lastUpdatedTextView.setText("最近更新:" + date);
super.setAdapter(adapter);
}
}

Jetbrains全家桶1年46，售后保障稳定

下拉刷新是重写的Listview ，所以在引用的时候，要加入该类的路径：

<com.news.utils.RefreshListView        android:id="@+id/list_news"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:dividerHeight="3dp" >    </com.news.utils.RefreshListView>

在使用的时候，新建该类对象。

listNews = (RefreshListView) view.findViewById(R.id.list_news);
// 新建适配器对象
ImportantNews impnews = new ImportantNews(context, position);
listNews.setAdapter(impnews);
listNews.setOnRefreshListener(new OnRefreshListener() {
@Override
public void onRefresh() {
// TODO Auto-generated method stub
listNews.onRefreshComplete();
}
});

效果：

下拉刷新Demo[通俗易懂]