1、概述
SwipeRefreshLayout是一种下拉刷新的组件，它被放到了V4包中，只允许有一个直接子类。
如下：mTarget是SwipeRefreshLayout的目标View，它是SwipeRefreshLayout的第一个子view，
SwipeRefreshLayout源码
2、简单的使用方法
如下：
SwipeRefreshLayout swipeRefreshLayout= (SwipeRefreshLayout) findViewById(R.id.swipeRefreshLayout);
//setColorSchemeResources()可以改变加载图标的颜色。
swipeRefreshLayout.setColorSchemeResources(new int[]{R.color.colorAccent, R.color.colorPrimary});
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
swipeRefreshLayout.setRefreshing(false);
}
});
3、显示空布局
但是，当没有数据的时候，怎么显示出数据为空的布局？可以查看google官方的例子，如下：
google官方例子
- 调用方法：
View mEmptyView = findViewById(android.R.id.empty);
loadMoreListView.setEmptyView(mEmptyView);
swipeRefreshLayout.setSwipeableChildren(R.id.LoadMoreListView,android.R.id.empty);
- 布局文件
<com.liyi.loadmorelistview.MultiSwipeRefreshLayout
android:id="@+id/swipeRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:id="@+id/LoadMoreListView"
android:layout_width="match_parent"
android:divider="@color/colorAccent"
android:footerDividersEnabled="true"
android:dividerHeight="2dp"
android:listSelector="@android:color/transparent"
android:layout_height="match_parent"/>
<TextView
android:id="@android:id/empty"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="List is empty! Click here to refresh."
android:layout_gravity="center"/>
</FrameLayout>
</com.liyi.loadmorelistview.MultiSwipeRefreshLayout>
如果没有自定义SwipeRefreshLayout，会出现即便没有到顶部，SwipeRefreshLayout也会刷新，正确的情况应该是：当ListView位于顶部时，下拉事件由SwipeRefreshLayout处理，否则由ListView处理
只要下拉，就触发刷新
- 自定义SwipeRefreshLayout
重写canChildScrollUp()方法，返回true，不进行刷新；false进行刷新。
onInterceptTouchEvent方法
public class MultiSwipeRefreshLayout extends SwipeRefreshLayout {
private View[] mSwipeableChildren;
public MultiSwipeRefreshLayout(Context context) {
super(context);
}
public MultiSwipeRefreshLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
/**
* 设置可以触发刷新事件的子view
* Set the children which can trigger a refresh by swiping down when they are visible. These
* views need to be a descendant of this view.
*/
public void setSwipeableChildren(final int... ids) {
assert ids != null;
mSwipeableChildren = new View[ids.length];
for (int i = 0; i < ids.length; i++) {
mSwipeableChildren[i] = findViewById(ids[i]);
}
}
/**
* 如果返回false，开始gesture
* <p/>
* This method controls when the swipe-to-refresh gesture is triggered. By returning false here
* we are signifying that the view is in a state where a refresh gesture can start.
* <p/>
* <p>As {@link android.support.v4.widget.SwipeRefreshLayout} only supports one direct child by
* default, we need to manually iterate through our swipeable children to see if any are in a
* state to trigger the gesture. If so we return false to start the gesture.
*/
@Override
public boolean canChildScrollUp() {
if (mSwipeableChildren != null && mSwipeableChildren.length > 0) {
for (View view : mSwipeableChildren) {
if (view != null && view.isShown()) {
if (view instanceof AbsListView) {
return canViewScrollUp(view);
}
}
}
}
return true;
}
private static boolean canViewScrollUp(View view) {
//负数，表示view上滑
return ViewCompat.canScrollVertically(view, -1);
}
}
没有数据
正在加载数据
有数据
在SwipeRefreshLayout中加入多个子View
Android中SwipeRefreshLayout和listview的冲突解决办法
4、关于SwipeRefreshLayout+ViewPager的滑动冲突
- 思路：因为是下拉刷新，只有纵向滑动的时候才有效，可以通过判断此时是纵向滑动还是横向滑动（X轴的移动距离大于Y轴的移动距离），纵向滑动就拦截事件，横向滑动不拦截。
- 可以重写onInterceptTouchEvent()方法，横向滑动不拦截（return false）
代码如下：
public class MultiSwipeRefreshLayout extends SwipeRefreshLayout {
private float startY;
private float startX;
// 记录viewPager是否拖拽的标记
private boolean mIsBeingDragged;
private final int mTouchSlop;
private View mSwipeableChildren;
public MultiSwipeRefreshLayout(Context context) {
this(context, null);
}
public MultiSwipeRefreshLayout(Context context, AttributeSet attrs) {
super(context, attrs);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
float currentX=ev.getX();
float currentY=ev.getY();
switch (ev.getAction()){
case MotionEvent.ACTION_DOWN:
startY=currentY;
startX=currentX;
mIsBeingDragged=false;
break;
case MotionEvent.ACTION_MOVE:
//如果viewpager正在拖拽中，那么不拦截它的事件，直接return false；
if(mIsBeingDragged){
return false;
}
float dx=Math.abs(currentX-startX);
float dy=Math.abs(currentY-startY);
// 如果X轴位移大于Y轴位移，那么将事件交给viewPager处理。
if(dx>dy && dx>mTouchSlop){
mIsBeingDragged=true;
return false;
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
mIsBeingDragged=false;
break;
}
// 如果是Y轴位移大于X轴，事件交给swipeRefreshLayout处理。
return super.onInterceptTouchEvent(ev);
}
/**
* 传入SwipeRefreshLayout的Target的id，如R.id.viewPager
* swipeRefreshLayout.setSwipeableChildren(R.id.viewPager);
* @param ids
*/
public void setSwipeableChildren(final int ids) {
mSwipeableChildren = findViewById(ids);
}
@Override
public boolean canChildScrollUp() {
return canViewScrollUp(mSwipeableChildren);
}
/**
* 根据传入的ViewPager，查找内部的ListView，并判断其是否到顶部
* @param view
* @return
*/
private static boolean canViewScrollUp(View view) {
if (view!=null && view instanceof ViewPager) {
for (int i = 0; i < ((ViewPager) view).getChildCount(); i++) {
View child = ((ViewPager) view).getChildAt(i);
if (child.isShown()) {
if (child instanceof RelativeLayout) {
View subChild = ((RelativeLayout) child).getChildAt(0);
if (subChild instanceof AbsListView) {
final AbsListView listView = (AbsListView) subChild;
return ViewCompat.canScrollVertically(listView, -1);
}
}
}
}
}
return false;
}
}
SwipeRefreshLayout+ViewPager—上拉
参考：
Android：SwipeRefreshLayout和ViewPager滑动冲突的原因和正确的解决方式
5、带上拉功能的SwipeRefreshLayout
地址为 ：https://github.com/OrangeGangsters/SwipyRefreshLayout
带上拉功能的SwipeRefreshLayout
