在ListView,GridView,RecyclerView列表滚动向底部一段距离,就自动显示一个返回顶部的按钮
1、添加依赖:
compile ('com.gaoneng.library:autoscrollbacklayout:1.1.1'){
exclude group: 'com.android.support', module: 'recyclerview-v7'
}
2、通过xml文件添加如下:
<?xml version="1.0" encoding="utf-8"?>
<com.gaoneng.library.AutoScrollBackLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/scroll_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingLeft="8dp"
android:paddingRight="8dp"
app:show_scroll="true">
<ListView
android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:drawSelectorOnTop="false" />
</com.gaoneng.library.AutoScrollBackLayout>
3、调用bindScrollBack():
AutoScrollBackLayout autoScrollBackLayout = (AutoScrollBackLayout) findViewById(R.id.scroll_layout);
ListView listView = (ListView) findViewById(android.R.id.list);
List<String> list = new ArrayList<>();
for (int i = 0; i < 20; i++) {
list.add("this is a test! in " + i);
}
listView.setAdapter(new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, list));
autoScrollBackLayout.bindScrollBack();
- 针对ListView和GridView,通过反射和动态代理的方式监听OnScrollListener,这样就不会影响已有的OnScrollListener的正常运行。
但是这里需要注意的是,如果已经使用
AbsListView.setOnScrollListener()
设置过监听, 一定要在其后面调用autoScrollBackLayout.bindScrollBack()
private void hookScrollListenerForListview() {
try {
//通过反射获取mOnScrollListener对象
Field scrollListenerField = AbsListView.class.getDeclaredField("mOnScrollListener");
scrollListenerField.setAccessible(true);
Object object = scrollListenerField.get(wrapView);
//需要被代理的目前对象
AbsListView.OnScrollListener target;
if (object == null) {
//如果mOnScrollListener没有设置过,就设置一个空的用来hook
target = new FakeScrollLitener();
} else {
target = (AbsListView.OnScrollListener) object;
}
//InvocationHandler对象,用于添加额外的控制处理
ScrollListenerInvocationHandler listenerInvocationHandler = new ScrollListenerInvocationHandler(target);
//Proxy.newProxyInstance生成动态代理对象
AbsListView.OnScrollListener proxy = listenerInvocationHandler.getProxy();
if (DEBUG) {
Log.i(TAG, "target=" + target.getClass().getName() + " ,proxy=" + proxy.getClass().getName() + ", proxied interfaces=" + Arrays.toString(proxy.getClass().getInterfaces()));
}
//将代理对象proxy设置到被反射的mOnScrollListener的字段中
scrollListenerField.set(wrapView, proxy);
} catch (Exception e) {
Log.e(TAG, e.toString());
}
}
- 针对RecyclerView,因为其内部的监听已经是
List<OnScrollListener>
形式,所以直接addOnScrollListener()
方式添加即可;
private void addScrollListenerForRecyclerView() {
((RecyclerView) wrapView).addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
if (myScrollLitener != null)
myScrollLitener.onScrollStateChanged(recyclerView, newState);
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
if (myScrollLitener != null) myScrollLitener.onScroll(recyclerView, dy, 0, 0);
}
});
}
attrs | value |
---|---|
app:show_scroll | true/false 是否自动显示返回按钮,默认true |
app:scroll_distance | dp 触发显示返回按钮的滚动距离,默认100dp |
app:show_animation | anim 按钮出现动画,默认 R.anim.fab_scale_up |
app:hide_animation | anim 按钮出现动画,默认 R.anim.fab_scale_down |
app:auto_arrow_icon | drawable 按钮图标,默认 R.drawable.go_top |
app:scroll_gravity | Gravity 按钮的位置,默认 Gravity.BOTTOM and Gravity.CENTER_HORIZONTAL |