Android中的SwiperefreshLayout

Question

我SwipeRefreshLayout在下面的布局中使用:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:background="@color/homePageBackground"
  android:orientation="vertical" >


<android.support.v4.widget.SwipeRefreshLayout
    android:id="@+id/swipeRefreshLayout_listView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >
<fragment
        android:id="@+id/announcementHomefragment"
        android:name="in.test.app.AnnouncementFragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/homePageBackground" >

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="15dp"
                android:background="@color/homePageBackground" >

                <TextView
                    android:id="@+id/newsTitle"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:layout_marginLeft="15dp"
                    android:layout_marginTop="5dp"
                    android:gravity="center"
                    android:text="@string/new_list"
                    android:textAppearance="?android:attr/textAppearanceSmall"
                    android:textColor="@color/white"
                    android:textStyle="bold" />

                <fragment
                    android:id="@+id/newshomefragment"
                    android:name="in.test.app.NewsFragment"
                    android:layout_width="wrap_content"
                    android:layout_height="190dp"
                    android:layout_below="@id/newsTitle"
                    android:layout_marginTop="-15dp" />

                <TextView
                    android:id="@+id/productTitle"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_below="@id/newshomefragment"
                    android:layout_gravity="center"
                    android:layout_marginLeft="15dp"
                    android:layout_marginTop="5dp"
                    android:gravity="center"
                    android:text="@string/product_in_home"
                    android:textAppearance="?android:attr/textAppearanceSmall"
                    android:textColor="@color/white"
                    android:textStyle="bold" />

                <fragment
                    android:id="@+id/proCategoryhomefragment"
                    android:name="in.test.app.CategoryFragment"
                    android:layout_width="wrap_content"
                    android:layout_height="170dp"
                    android:layout_below="@id/productTitle"
                    android:layout_marginTop="-15dp" />

                <TextView
                    android:id="@+id/trainingTitle"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_below="@id/proCategoryhomefragment"
                    android:layout_gravity="center"
                    android:layout_marginLeft="15dp"
                    android:layout_marginTop="2dp"
                    android:gravity="center"
                    android:text="@string/trainings_in_home"
                    android:textAppearance="?android:attr/textAppearanceSmall"
                    android:textColor="@color/white"
                    android:textStyle="bold" />

                <fragment
                    android:id="@+id/trainingfragment"
                    android:name="in.test.app.TrainingFragment"
                    android:layout_width="match_parent"
                    android:layout_height="180dp"
                    android:layout_below="@id/trainingTitle"
                    android:layout_marginBottom="10dp"
                    android:layout_marginTop="-15dp" />
            </RelativeLayout>
        </ScrollView>
    </LinearLayout>
</android.support.v4.widget.SwipeRefreshLayout>

当我下拉时SwipeRefreshLayout它正在工作,但正如您在上面的代码中看到的那样,我在其中有一个滚动视图.因此,当我向下拉滚动视图时,它会下降并且一半的图像没有显示,因为它已经下降.当我试图再次拉起时,我的滚动视图不会上升.相反,SwipeRefreshLayout正在接听电话.我该怎么办？

请帮帮我.

Answer 1

我想说最好有一个带有监听器的扩展SwipeRefreshLayout,以便能够从显示此布局的类中添加各种条件.

类似于以下内容: GeneralSwipeRefreshLayout.java

public class GeneralSwipeRefreshLayout extends SwipeRefreshLayout {   
  private OnChildScrollUpListener mScrollListenerNeeded;

  public interface OnChildScrollUpListener {
    boolean canChildScrollUp();
  }

  public GeneralSwipeRefreshLayout(Context context) {
    super(context);   
  }
  public GeneralSwipeRefreshLayout(Context context, AttributeSet attrs) {
    super(context, attrs);   
  }

 /**
  * Listener that controls if scrolling up is allowed to child views or not
  */
  public void setOnChildScrollUpListener(OnChildScrollUpListener listener) {
    mScrollListenerNeeded = listener;   
  }

  @Override
  public boolean canChildScrollUp() {
    if (mScrollListenerNeeded == null) {
      Log.e(GeneralSwipeRefreshLayout.class.getSimpleName(), "listener is not defined!");
    }
    return mScrollListenerNeeded != null && mScrollListenerNeeded.canChildScrollUp();
  }
}

然后在显示包含ListView或GridView布局的SwipeRefreshLayout的类中,您可以执行以下操作:

mSwipeLayout.setOnChildScrollUpListener(new OnChildScrollUpListener() {
  @Override
  public boolean canChildScrollUp() {
    return mListView.getFirstVisiblePosition() > 0 || 
           mListView.getChildAt(0) == null || 
           mListView.getChildAt(0).getTop() < 0;
  }
});

Answer 2

只需创建一个扩展 SwipeRefreshLayout和覆盖该方法的类canChildScrollUp().如果要向下滚动以进行控制,则返回true.

例如对于scrollview你可以试试这个,

@override.
boolean canChildScrollUp()
{
   //your condition to check scrollview reached at top while scrolling
   if(scrollview.getScrollY() == 0.0)
      return true;
   else
      return false;
}

Answer 3

正如其他人已经说过的那样,如果您没有可滚动视图(即listview)作为SwipeRefreshLayout的直接子项,则库存canChildScrollUp将不起作用.

与SwipeRefreshLayout用于检查子视图滚动的能力的简单逻辑有关.

我在ActionbarActivity中使用了ListView,并希望在listview为空时包含一个空视图.这导致了问题,因为SwipeRefreshLayout类只能有一个子节点.请注意,它还检查此子项的scrollUp功能,以确定下拉是否导致子项滚动,或者是否导致子项内容刷新.

因此,如果您想使用与SwipeRefreshLayout相同的逻辑,只需扩展该类,并创建一个方法,以允许您将句柄传递给可滚动视图.请注意,库存实现使用canScrollVertically(),它完全符合我们的要求,但仅出现在SDK> = 14中.

另外,在扩展类时,不要忘记包含包含参数"AttributeSet"的构造函数,否则在布局文件中使用该类时会遇到问题.

因此,在您的Activity的onCreate方法(在我的情况下,它是一个ActionBarActivity)中包含列表视图,只需调用setMyScrollableView传递ListView或您滚动使用的任何视图.

/*Constructor*/
public MySwipeRefreshLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub
}


 View mMyScrollableView = null;  //The content that get's pulled down.
 /*Method used to pass in my scrollable view*/
 public void setMyScrollableView(View view){
    mMyScrollableView = view;
 }

/**
 * @return Whether it is possible for the child view of this layout to
 * scroll up.  This was taken for the most part directly from SwipeRefreshLayout
 */
public boolean canChildScrollUp() {
    if(mMyScrollableView == null)
      return false;
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (mMyScrollableView instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) mMyScrollableView;
            return absListView.getChildCount() > 0
        && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
        .getTop() < absListView.getPaddingTop());
        } else {
            return mMyScrollableView.getScrollY() > 0;
        }
    } else {
        return ViewCompat.canScrollVertically(mMyScrollableView, -1);
    }
}