android 安卓自定义listview实现下拉刷新
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【1】、重写listView
public class MyListView extends ListView implements OnScrollListener {
private final static int RELEASE_To_REFRESH = 0;// 下拉过程的状态值
private final static int PULL_To_REFRESH = 1; // 从下拉返回到不刷新的状态值
private final static int REFRESHING = 2;// 正在刷新的状态值
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 = 3;
private LayoutInflater inflater;
// ListView头部下拉刷新的布局
private LinearLayout headerView;
private TextView lvHeaderTipsTv;
private TextView lvHeaderLastUpdatedTv;
private ImageView lvHeaderArrowIv;
private ProgressBar lvHeaderProgressBar;
// 定义头部下拉刷新的布局的高度
private int headerContentHeight;
private RotateAnimation animation;
private RotateAnimation reverseAnimation;
private int startY;
private int state;
private boolean isBack;
// 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 OnRefreshListener refreshListener;
private boolean isRefreshable;
public MyListView(Context context) {
super(context);
init(context);
}
public MyListView(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);
headerView = (LinearLayout) inflater.inflate(R.layout.lv_header, null);
lvHeaderTipsTv = (TextView) headerView
.findViewById(R.id.lvHeaderTipsTv);
lvHeaderLastUpdatedTv = (TextView) headerView
.findViewById(R.id.lvHeaderLastUpdatedTv);
lvHeaderArrowIv = (ImageView) headerView
.findViewById(R.id.lvHeaderArrowIv);
// 设置下拉刷新图标的最小高度和宽度
lvHeaderArrowIv.setMinimumWidth(70);
lvHeaderArrowIv.setMinimumHeight(50);
lvHeaderProgressBar = (ProgressBar) headerView
.findViewById(R.id.lvHeaderProgressBar);
measureView(headerView);
headerContentHeight = headerView.getMeasuredHeight();
// 设置内边距，正好距离顶部为一个负的整个布局的高度，正好把头部隐藏
headerView.setPadding(0, -1 * headerContentHeight, 0, 0);
// 重绘一下
headerView.invalidate();
// 将下拉刷新的布局加入ListView的顶部
addHeaderView(headerView, null, false);
// 设置滚动监听事件
setOnScrollListener(this);
// 设置旋转动画事件
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);
// 一开始的状态就是下拉刷新完的状态，所以为DONE
state = DONE;
// 是否正在刷新
isRefreshable = false;
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
if (firstVisibleItem == 0) {
isRefreshable = true;
} else {
isRefreshable = false;
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (isRefreshable) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
if (!isRecored) {
isRecored = true;
startY = (int) ev.getY();// 手指按下时记录当前位置
}
break;
case MotionEvent.ACTION_UP:
if (state != REFRESHING && state != LOADING) {
if (state == PULL_To_REFRESH) {
state = DONE;
changeHeaderViewByState();
}
if (state == RELEASE_To_REFRESH) {
state = REFRESHING;
changeHeaderViewByState();
onLvRefresh();
}
}
isRecored = false;
isBack = false;
break;
case MotionEvent.ACTION_MOVE:
int tempY = (int) ev.getY();
if (!isRecored) {
isRecored = true;
startY = tempY;
}
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 < headerContentHeight)// 由松开刷新状态转变到下拉刷新状态
&& (tempY - startY) > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
// 一下子推到顶了
else if (tempY - startY <= 0) {// 由松开刷新状态转变到done状态
state = DONE;
changeHeaderViewByState();
}
}
// 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
if ((tempY - startY) / RATIO >= headerContentHeight) {// 由done或者下拉刷新状态转变到松开刷新
state = RELEASE_To_REFRESH;
isBack = true;
changeHeaderViewByState();
}
// 上推到顶了
else if (tempY - startY <= 0) {// 由DOne或者下拉刷新状态转变到done状态
state = DONE;
changeHeaderViewByState();
}
}
// done状态下
if (state == DONE) {
if (tempY - startY > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
}
// 更新headView的size
if (state == PULL_To_REFRESH) {
headerView.setPadding(0, -1 * headerContentHeight
+ (tempY - startY) / RATIO, 0, 0);
}
// 更新headView的paddingTop
if (state == RELEASE_To_REFRESH) {
headerView.setPadding(0, (tempY - startY) / RATIO
- headerContentHeight, 0, 0);
}
}
break;
default:
break;
}
}
return super.onTouchEvent(ev);
}
// 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:
lvHeaderArrowIv.setVisibility(View.VISIBLE);
lvHeaderProgressBar.setVisibility(View.GONE);
lvHeaderTipsTv.setVisibility(View.VISIBLE);
lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);
lvHeaderArrowIv.clearAnimation();// 清除动画
lvHeaderArrowIv.startAnimation(animation);// 开始动画效果
lvHeaderTipsTv.setText("松开刷新");
break;
case PULL_To_REFRESH:
lvHeaderProgressBar.setVisibility(View.GONE);
lvHeaderTipsTv.setVisibility(View.VISIBLE);
lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);
lvHeaderArrowIv.clearAnimation();
lvHeaderArrowIv.setVisibility(View.VISIBLE);
// 是由RELEASE_To_REFRESH状态转变来的
if (isBack) {
isBack = false;
lvHeaderArrowIv.clearAnimation();
lvHeaderArrowIv.startAnimation(reverseAnimation);
lvHeaderTipsTv.setText("下拉刷新");
} else {
lvHeaderTipsTv.setText("下拉刷新");
}
break;
case REFRESHING:
headerView.setPadding(0, 0, 0, 0);
lvHeaderProgressBar.setVisibility(View.VISIBLE);
lvHeaderArrowIv.clearAnimation();
lvHeaderArrowIv.setVisibility(View.GONE);
lvHeaderTipsTv.setText("正在刷新...");
lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);
break;
case DONE:
headerView.setPadding(0, -1 * headerContentHeight, 0, 0);
lvHeaderProgressBar.setVisibility(View.GONE);
lvHeaderArrowIv.clearAnimation();
lvHeaderArrowIv.setImageResource(R.drawable.arrow);
lvHeaderTipsTv.setText("下拉刷新");
lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);
break;
}
}
// 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 params = child.getLayoutParams();
if (params == null) {
params = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0,
params.width);
int lpHeight = params.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 setonRefreshListener(OnRefreshListener refreshListener) {
this.refreshListener = refreshListener;
isRefreshable = true;
}
public interface OnRefreshListener {
public void onRefresh();
}
public void onRefreshComplete() {
state = DONE;
lvHeaderLastUpdatedTv.setText("最近更新:" + new Date().toLocaleString());
changeHeaderViewByState();
}
private void onLvRefresh() {
if (refreshListener != null) {
refreshListener.onRefresh();
}
}
public void setAdapter(BaseAdapter adapter) {
lvHeaderLastUpdatedTv.setText("最近更新:" + new Date().toLocaleString());
super.setAdapter(adapter);
}
}【2】刷新头部xml文件lv_header.xml
<?xml version="1.0" encoding="utf-8"?> <!-- ListView的头部 --> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#000000" > <!-- 内容 --> <RelativeLayout android:id="@+id/head_contentLayout" android:layout_width="fill_parent" android:layout_height="wrap_content" android:paddingLeft="30dp" > <!-- 箭头图像、进度条 --> <FrameLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_centerVertical="true" > <!-- 箭头 --> <ImageView android:id="@+id/lvHeaderArrowIv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:src="@drawable/arrow" /> <!-- 进度条 --> <ProgressBar android:id="@+id/lvHeaderProgressBar" style="?android:attr/progressBarStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:visibility="gone" /> </FrameLayout> <!-- 提示、最近更新 --> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:gravity="center_horizontal" android:orientation="vertical" > <!-- 提示 --> <TextView android:id="@+id/lvHeaderTipsTv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="下拉刷新" android:textColor="@color/white" android:textSize="20sp" /> <!-- 最近更新 --> <TextView android:id="@+id/lvHeaderLastUpdatedTv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="上次更新" android:textColor="@color/gold" android:textSize="10sp" /> </LinearLayout> </RelativeLayout> </LinearLayout>
【3】调用方法
adapter = new LvAdapter(list, this);
lv.setAdapter(adapter);
lv.setonRefreshListener(new OnRefreshListener() {
@Override
public void onRefresh() {
new AsyncTask<Void, Void, Void>() {
protected Void doInBackground(Void... params) {
try {
Thread.sleep(1000);
} catch (Exception e) {
e.printStackTrace();
}
list.add("刷新后添加的内容");
return null;
}
@Override
protected void onPostExecute(Void result) {
adapter.notifyDataSetChanged();
lv.onRefreshComplete();
}
}.execute(null, null, null);
}
});
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