Android刷新加载框架详解
时间:2019-04-11
本文章向大家介绍Android刷新加载框架详解，主要包括Android刷新加载框架详解使用实例、应用技巧、基本知识点总结和需要注意事项，具有一定的参考价值，需要的朋友可以参考一下。
本文实例为大家分享了Android刷新加载框架的具体代码，供大家参考，具体内容如下
1.定义一个接口控制下拉和上拉
public interface Pullable {
/**
* 是否可下拉
*/
boolean canPullDown();
/**
* 是否可上拉
*/
boolean canPullUp();
}
2.定义一个刷新加载布局
public class PullToRefreshLayout extends RelativeLayout {
/**
* 头
*/
private View headView;//头视图
private ImageView headIv;//头图标
private TextView headTv;//头文字
private int headHeight;//头高度
private float headBorder;//头临界
/**
* 拉
*/
private View pullView;//拉视图
private int pullHeight;//拉高度
private int pullWidth;//拉宽度
/**
* 尾
*/
private View footView;//尾视图
private ImageView footIv;//尾图标
private TextView footTv;//尾文字
private int footHeight;//尾高度
private float footBorder;//尾临界
/**
* 状态
*/
public static final int INIT = 0;//初始
public static final int RELEASE_TO_REFRESH = 1;//释放刷新
public static final int REFRESHING = 2;//正在刷新
public static final int RELEASE_TO_LOAD = 3;//释放加载
public static final int LOADING = 4;//正在加载
public static final int DONE = 5;//完成
private int state = INIT;
/**
* 接口
*/
private OnRefreshListener mListener;
private float downY;//按下时Y坐标
private float lastY;//上一个Y坐标
private float pullDownY = 0;//下拉偏移量
private float pullUpY = 0;//上拉偏移量
private int offset;//偏移量
/**
* 动画
*/
private RotateAnimation rotateAnimation;
/**
* 线程
*/
private Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
if (msg != null) {
switch (msg.what) {
case 1:
headIv.clearAnimation();
break;
case 2:
footIv.clearAnimation();
break;
default:
break;
}
pullDownY = 0;
pullUpY = 0;
requestLayout();
state = INIT;
refreshViewByState();
isTouch = true;
}
}
};
/**
* 第一次执行布局
*/
private boolean isLayout = false;
/**
* 在刷新过程中滑动操作
*/
private boolean isTouch = false;
/**
* 手指滑动距离与下拉头的滑动距离比，中间会随正切函数变化
*/
private float radio = 2;
/**
* 过滤多点触碰
*/
private int mEvents;
/**
* 这两个变量用来控制pull的方向，如果不加控制，当情况满足可上拉又可下拉时没法下拉
*/
private boolean canPullDown = true;
private boolean canPullUp = true;
public void setOnRefreshListener(OnRefreshListener listener) {
mListener = listener;
}
public PullToRefreshLayout(Context context) {
super(context);
initView(context);
}
public PullToRefreshLayout(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
}
public PullToRefreshLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView(context);
}
private void initView(Context context) {
rotateAnimation = (RotateAnimation) AnimationUtils.loadAnimation(context, R.anim.rotating);
}
private void refreshViewByState() {
switch (state) {
case INIT:
// 下拉布局初始状态
headIv.setImageResource("下拉刷新显示的图片");
headTv.setText("下拉刷新");
// 上拉布局初始状态
footIv.setImageResource("上拉加载显示的图片");
footTv.setText("上拉加载");
break;
case RELEASE_TO_REFRESH:
// 释放刷新状态
headIv.setImageResource("释放刷新显示的图片");
headTv.setText("释放刷新");
break;
case REFRESHING:
// 正在刷新状态
headIv.setImageResource("正在刷新显示的图片");
headTv.setText("正在刷新");
break;
case RELEASE_TO_LOAD:
// 释放加载状态
footIv.setImageResource("释放加载显示的图片");
footTv.setText("释放加载");
break;
case LOADING:
// 正在加载状态
footIv.setImageResource("正在加载显示的图片");
footTv.setText("正在加载");
break;
case DONE:
// 刷新或加载完毕，啥都不做
break;
}
}
/**
* 不限制上拉或下拉
*/
private void releasePull() {
canPullDown = true;
canPullUp = true;
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
switch (ev.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
downY = ev.getY();
lastY = downY;
mEvents = 0;
releasePull();
if (state != REFRESHING && state != LOADING) {
isTouch = true;
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
case MotionEvent.ACTION_POINTER_UP:
// 过滤多点触碰
mEvents = -1;
break;
case MotionEvent.ACTION_MOVE:
if (mEvents == 0) {
if (pullDownY > 0 || (((Pullable) pullView).canPullDown()
&& canPullDown && state != LOADING && state != REFRESHING)) {
// 可以下拉，正在加载时不能下拉
// 对实际滑动距离做缩小，造成用力拉的感觉
pullDownY = pullDownY + (ev.getY() - lastY) / radio;
if (pullDownY < 0) {
pullDownY = 0;
canPullDown = false;
canPullUp = true;
}
if (pullDownY > getMeasuredHeight()) {
pullDownY = getMeasuredHeight();
}
if (state == REFRESHING) {
// 正在刷新的时候触摸移动
isTouch = false;
}
} else if (pullUpY < 0
|| (((Pullable) pullView).canPullUp() && canPullUp && state != REFRESHING && state != LOADING)) {
// 可以上拉，正在刷新时不能上拉
pullUpY = pullUpY + (ev.getY() - lastY) / radio;
if (pullUpY > 0) {
pullUpY = 0;
canPullDown = true;
canPullUp = false;
}
if (pullUpY < -getMeasuredHeight()) {
pullUpY = -getMeasuredHeight();
}
if (state == LOADING) {
// 正在加载的时候触摸移动
isTouch = false;
}
}
}
if (isTouch) {
lastY = ev.getY();
if (pullDownY > 0 || pullUpY < 0) {
requestLayout();
}
if (pullDownY > 0) {
if (pullDownY <= headBorder && (state == RELEASE_TO_REFRESH || state == DONE)) {
// 如果下拉距离没达到刷新的距离且当前状态是释放刷新，改变状态为下拉刷新
state = INIT;
refreshViewByState();
}
if (pullDownY >= headBorder && state == INIT) {
// 如果下拉距离达到刷新的距离且当前状态是初始状态刷新，改变状态为释放刷新
state = RELEASE_TO_REFRESH;
refreshViewByState();
}
} else if (pullUpY < 0) {
// 下面是判断上拉加载的，同上，注意pullUpY是负值
if (-pullUpY <= footBorder && (state == RELEASE_TO_LOAD || state == DONE)) {
state = INIT;
refreshViewByState();
}
// 上拉操作
if (-pullUpY >= footBorder && state == INIT) {
state = RELEASE_TO_LOAD;
refreshViewByState();
}
}
// 因为刷新和加载操作不能同时进行，所以pullDownY和pullUpY不会同时不为0，因此这里用(pullDownY +
// Math.abs(pullUpY))就可以不对当前状态作区分了
if ((pullDownY + Math.abs(pullUpY)) > 8) {
// 防止下拉过程中误触发长按事件和点击事件
ev.setAction(MotionEvent.ACTION_CANCEL);
}
}
break;
case MotionEvent.ACTION_UP:
if (pullDownY > headBorder || -pullUpY > footBorder) {
// 正在刷新时往下拉（正在加载时往上拉），释放后下拉头（上拉头）不隐藏
isTouch = false;
}
if (state == RELEASE_TO_REFRESH) {
state = REFRESHING;
refreshViewByState();
// 刷新操作
if (mListener != null) {
canPullDown = false;
pullDownY = headBorder;
pullUpY = 0;
requestLayout();
headIv.startAnimation(rotateAnimation);
mListener.onRefresh(this);
}
} else if (state == RELEASE_TO_LOAD) {
state = LOADING;
refreshViewByState();
// 加载操作
if (mListener != null) {
canPullUp = false;
pullDownY = 0;
pullUpY = -footBorder;
requestLayout();
footIv.startAnimation(rotateAnimation);
mListener.onLoadMore(this);
}
} else {
pullDownY = 0;
pullUpY = 0;
requestLayout();
}
default:
break;
}
// 事件分发交给父类
super.dispatchTouchEvent(ev);
return true;
}
public void hideHeadView() {
handler.sendEmptyMessage(1);
}
public void hideFootView() {
handler.sendEmptyMessage(2);
}
private void initView() {
// 初始化下拉布局
headIv = (ImageView) headView.findViewById(R.id.iv_head);
headTv = (TextView) headView.findViewById(R.id.tv_head);
//初始化上拉布局
footIv = (ImageView) footView.findViewById(R.id.iv_foot);
footTv = (TextView) footView.findViewById(R.id.tv_foot);
refreshViewByState();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if (!isLayout) {
// 这里是第一次进来的时候做一些初始化
headView = getChildAt(0);
pullView = getChildAt(1);
footView = getChildAt(2);
headBorder = ((ViewGroup) headView).getChildAt(0).getMeasuredHeight();
footBorder = ((ViewGroup) footView).getChildAt(0).getMeasuredHeight();
headHeight = headView.getMeasuredHeight();
pullHeight = pullView.getMeasuredHeight();
footHeight = footView.getMeasuredHeight();
pullWidth = pullView.getMeasuredWidth();
initView();
isLayout = true;
}
// 改变子控件的布局，这里直接用(pullDownY + pullUpY)作为偏移量，这样就可以不对当前状态作区分
offset = (int) (pullDownY + pullUpY);
headView.layout(0, -headHeight + offset, pullWidth, offset);
pullView.layout(0, offset, pullWidth, pullHeight + offset);
footView.layout(0, pullHeight + offset, pullWidth, pullHeight + footHeight + offset);
}
public interface OnRefreshListener {
void onRefresh(PullToRefreshLayout pullToRefreshLayout);
void onLoadMore(PullToRefreshLayout pullToRefreshLayout);
}
}
3.自定义View
ListView
public class PullableListView extends ListView implements Pullable {
public PullableListView(Context context) {
super(context);
}
public PullableListView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PullableListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean canPullDown() {
if (getCount() == 0) {
// 没有item的时候也可以下拉刷新
return false;
} else if (getFirstVisiblePosition() == 0 && getChildAt(0).getTop() >= 0) {
// 滑到ListView的顶部了
return true;
} else
return false;
}
@Override
public boolean canPullUp() {
if (getCount() == 0) {
// 没有item的时候也可以上拉加载
return false;
} else if (getLastVisiblePosition() == (getCount() - 1)) {
// 滑到底部了
if (getChildAt(getLastVisiblePosition() - getFirstVisiblePosition()) != null
&& getChildAt(getLastVisiblePosition() - getFirstVisiblePosition())
.getBottom() <= getMeasuredHeight())
return true;
}
return false;
}
}
GridView
public class PullableGridView extends GridView implements Pullable {
public PullableGridView(Context context) {
super(context);
}
public PullableGridView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PullableGridView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean canPullDown() {
if (getCount() == 0) {
// 没有item的时候也可以下拉刷新
return false;
} else if (getFirstVisiblePosition() == 0
&& getChildAt(0).getTop() >= 0) {
// 滑到顶部了
return true;
} else
return false;
}
@Override
public boolean canPullUp() {
if (getCount() == 0) {
// 没有item的时候也可以上拉加载
return false;
} else if (getLastVisiblePosition() == (getCount() - 1)) {
// 滑到底部了
if (getChildAt(getLastVisiblePosition() - getFirstVisiblePosition()) != null
&& getChildAt(
getLastVisiblePosition()
- getFirstVisiblePosition()).getBottom() <= getMeasuredHeight())
return true;
}
return false;
}
}
RecyclerView
public class PullableRecyclerView extends RecyclerView implements Pullable {
public PullableRecyclerView(Context context) {
super(context);
}
public PullableRecyclerView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
public PullableRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean canPullDown() {
RecyclerView.LayoutManager layoutManager = getLayoutManager();
if (layoutManager instanceof LinearLayoutManager) {
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
if (linearLayoutManager.getItemCount() == 0) {
return false;
} else if (linearLayoutManager.findFirstVisibleItemPosition() == 0 && linearLayoutManager.getChildAt(0).getTop() >= 0) {
return true;
} else {
return false;
}
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
if (staggeredGridLayoutManager.getItemCount() == 0) {
return false;
} else {
int[] firstVisibleItems = null;
firstVisibleItems = staggeredGridLayoutManager.findFirstVisibleItemPositions(firstVisibleItems);
if (firstVisibleItems != null && firstVisibleItems.length > 0) {
if (staggeredGridLayoutManager.getChildCount() + firstVisibleItems[0] == staggeredGridLayoutManager.getItemCount()) {
return true;
}
}
}
}
return false;
}
@Override
public boolean canPullUp() {
RecyclerView.LayoutManager layoutManager = getLayoutManager();
if (layoutManager instanceof LinearLayoutManager) {
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
if (linearLayoutManager.getItemCount() == 0) {
return false;
} else if (linearLayoutManager.findLastVisibleItemPosition() == (linearLayoutManager.getItemCount() - 1)) {
if (linearLayoutManager.getChildAt(linearLayoutManager.findLastVisibleItemPosition() - linearLayoutManager.findFirstVisibleItemPosition()) != null
&& linearLayoutManager.getChildAt(linearLayoutManager.findLastVisibleItemPosition() - linearLayoutManager.findFirstVisibleItemPosition()).getBottom() <= getMeasuredHeight()) {
return true;
}
}
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
if (staggeredGridLayoutManager.getItemCount() == 0) {
return false;
} else {
int[] lastPositions = new int[staggeredGridLayoutManager.getSpanCount()];
lastPositions = staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions);
if (findMax(lastPositions) >= staggeredGridLayoutManager.getItemCount() - 1) {
return true;
}
}
}
return false;
}
private int findMax(int[] lastPositions) {
int max = lastPositions[0];
for (int value : lastPositions) {
if (value > max) {
max = value;
}
}
return max;
}
}
ExpandableListView
public class PullableExpandableListView extends ExpandableListView implements
Pullable {
public PullableExpandableListView(Context context) {
super(context);
}
public PullableExpandableListView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PullableExpandableListView(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean canPullDown() {
if (getCount() == 0) {
// 没有item的时候也可以下拉刷新
return false;
} else if (getFirstVisiblePosition() == 0
&& getChildAt(0).getTop() >= 0) {
// 滑到顶部了
return true;
} else
return false;
}
@Override
public boolean canPullUp() {
if (getCount() == 0) {
// 没有item的时候也可以上拉加载
return false;
} else if (getLastVisiblePosition() == (getCount() - 1)) {
// 滑到底部了
if (getChildAt(getLastVisiblePosition() - getFirstVisiblePosition()) != null
&& getChildAt(
getLastVisiblePosition()
- getFirstVisiblePosition()).getBottom() <= getMeasuredHeight())
return true;
}
return false;
}
}
ScrollView
public class PullableScrollView extends ScrollView implements Pullable {
public PullableScrollView(Context context) {
super(context);
}
public PullableScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PullableScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean canPullDown() {
if (getScrollY() == 0)
return true;
else
return false;
}
@Override
public boolean canPullUp() {
if (getScrollY() >= (getChildAt(0).getHeight() - getMeasuredHeight()))
return true;
else
return false;
}
}
WebView
public class PullableWebView extends WebView implements Pullable {
public PullableWebView(Context context) {
super(context);
}
public PullableWebView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PullableWebView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean canPullDown() {
if (getScrollY() == 0)
return true;
else
return false;
}
@Override
public boolean canPullUp() {
if (getScrollY() >= getContentHeight() * getScale()
- getMeasuredHeight())
return true;
else
return false;
}
}
ImageView
public class PullableImageView extends ImageView implements Pullable
{
public PullableImageView(Context context)
{
super(context);
}
public PullableImageView(Context context, AttributeSet attrs)
{
super(context, attrs);
}
public PullableImageView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
}
@Override
public boolean canPullDown()
{
return true;
}
@Override
public boolean canPullUp()
{
return true;
}
}
TextView
public class PullableTextView extends TextView implements Pullable {
public PullableTextView(Context context) {
super(context);
}
public PullableTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PullableTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean canPullDown() {
return true;
}
@Override
public boolean canPullUp() {
return true;
}
}
4.使用示例(以ListView为例)
<view.PullToRefreshLayout
android:id="@+id/ptrl"
android:layout_width="match_parent"
android:layout_height="match_parent">
<include layout="@layout/head" />
<view.PullableListView
android:id="@+id/plv"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<include layout="@layout/foot" />
</view.PullToRefreshLayout>
head
<?xml version="1.0" encoding="UTF-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/head_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/darker_gray">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:paddingBottom="20dp"
android:paddingTop="20dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerInParent="true">
<ImageView
android:id="@+id/iv_head"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_centerVertical="true"
android:layout_marginLeft="60dp"
android:scaleType="fitXY" />
<TextView
android:id="@+id/tv_head"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:textColor="@android:color/white"
android:textSize="16sp" />
</RelativeLayout>
</RelativeLayout>
</RelativeLayout>
foot
<?xml version="1.0" encoding="UTF-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/loadmore_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/darker_gray">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:paddingBottom="20dp"
android:paddingTop="20dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerInParent="true">
<ImageView
android:id="@+id/iv_foot"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_centerVertical="true"
android:layout_marginLeft="60dp"
android:scaleType="fitXY" />
<TextView
android:id="@+id/tv_foot"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:textColor="@android:color/white"
android:textSize="16sp" />
</RelativeLayout>
</RelativeLayout>
</RelativeLayout>
4.注意
自定义的View跟正常的View的使用没有什么差别
如需实现刷新加载，必须使ptrl.setOnRefreshListener(PullToRefreshLayout.OnRefreshListener onRefreshListener);
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。
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