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我们知道xUtils中的bitmapUtils与listview相配合可以实现滚动时暂停加载

只需要一句话:

listview.addOnScrollListener(new PauseOnScrollListener(bitmapUtils, false, true));

然而在我所使用的xUtils2.6版本上,如果想对recyclerView使用相似的方法是行不通的

(ps:因为xUtils3只支持api14,所以我没用xUtils3)

recyclerView.addOnScrollListener(new PauseOnScrollListener(bitmapUtils, false, true));

因为参数需要的是RecyclerView.OnScrollListener,

而xUtils只提供了实现AbsListView.OnScrollListener的listener

这个时候只能自己动手改动xUtils源码了

进入到PauseOnScrollListener的源码中

import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import com.lidroid.xutils.BitmapUtils;
import com.lidroid.xutils.task.TaskHandler;public class PauseOnScrollListener implements OnScrollListener {private TaskHandler taskHandler;private final boolean pauseOnScroll;private final boolean pauseOnFling;private final OnScrollListener externalListener;/*** Constructor** @param taskHandler   {@linkplain BitmapUtils} instance for controlling* @param pauseOnScroll Whether {@linkplain BitmapUtils#pause() pause loading} during touch scrolling* @param pauseOnFling  Whether {@linkplain BitmapUtils#pause() pause loading} during fling*/public PauseOnScrollListener(TaskHandler taskHandler, boolean pauseOnScroll, boolean pauseOnFling) {this(taskHandler, pauseOnScroll, pauseOnFling, null);}/*** Constructor** @param taskHandler    {@linkplain BitmapUtils} instance for controlling* @param pauseOnScroll  Whether {@linkplain BitmapUtils#pause() pause loading} during touch scrolling* @param pauseOnFling   Whether {@linkplain BitmapUtils#pause() pause loading} during fling* @param customListener Your custom {@link android.widget.AbsListView.OnScrollListener} for {@linkplain android.widget.AbsListView list view} which also will*                       be get scroll events*/public PauseOnScrollListener(TaskHandler taskHandler, boolean pauseOnScroll, boolean pauseOnFling, OnScrollListener customListener) {this.taskHandler = taskHandler;this.pauseOnScroll = pauseOnScroll;this.pauseOnFling = pauseOnFling;externalListener = customListener;}@Overridepublic void onScrollStateChanged(AbsListView view, int scrollState) {switch (scrollState) {case OnScrollListener.SCROLL_STATE_IDLE:taskHandler.resume();break;case OnScrollListener.SCROLL_STATE_TOUCH_SCROLL:if (pauseOnScroll) {taskHandler.pause();}break;case OnScrollListener.SCROLL_STATE_FLING:if (pauseOnFling) {taskHandler.pause();}break;}if (externalListener != null) {externalListener.onScrollStateChanged(view, scrollState);}}@Overridepublic void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {if (externalListener != null) {externalListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);}}
}

意外地发现不是很长,其中主要起作用的除了两个重写的方法外,就是TaskHandler这个接口了

BitmapUtils其实是继承了TaskHandler

TaskHandler对handler进行了进一步的封装,方便控制异步任务

TaskHandler具有pause()和resume()两个很重要的方法,由BitmapUtils等实现

@Overridepublic void pause() {pauseTask = true;flushCache();}@Overridepublic void resume() {pauseTask = false;synchronized (pauseTaskLock) {pauseTaskLock.notifyAll();}}

看到这里思路就比较明显了,我们继承RecyclerView.OnScrollListener并重写其中的回调方法

在回调方法中调用TaskHandler的api,即可达到想要的效果.

精简后的代码如下

import com.lidroid.xutils.BitmapUtils;
import com.lidroid.xutils.task.TaskHandler;import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.RecyclerView.OnScrollListener;;public class PauseOnScrollListener extends RecyclerView.OnScrollListener {private TaskHandler taskHandler;private boolean pauseOnScroll;private boolean pauseOnFling;private OnScrollListener externalListener;/*** Constructor** @param taskHandler*            {@linkplain BitmapUtils} instance for controlling* @param pauseOnScroll*            Whether {@linkplain BitmapUtils#pause() pause loading} during*            touch scrolling* @param pauseOnFling*            Whether {@linkplain BitmapUtils#pause() pause loading} during*            fling*/public PauseOnScrollListener(TaskHandler taskHandler,boolean pauseOnScroll, boolean pauseOnFling) {this(taskHandler, pauseOnScroll, pauseOnFling, null);}/*** Constructor** @param taskHandler*            {@linkplain BitmapUtils} instance for controlling* @param pauseOnScroll*            Whether {@linkplain BitmapUtils#pause() pause loading} during*            touch scrolling* @param pauseOnFling*            Whether {@linkplain BitmapUtils#pause() pause loading} during*            fling* @param customListener*            Your custom*            {@link android.widget.AbsListView.OnScrollListener} for*            {@linkplain android.widget.AbsListView list view} which also*            will be get scroll events*/public MyPauseOnScrollListener(TaskHandler taskHandler,boolean pauseOnScroll, boolean pauseOnFling,OnScrollListener customListener) {this.taskHandler = taskHandler;this.pauseOnScroll = pauseOnScroll;this.pauseOnFling = pauseOnFling;externalListener = customListener;}@Overridepublic void onScrollStateChanged(RecyclerView view, int newState) {switch (newState) {case 0:taskHandler.resume();break;case 1:if (pauseOnScroll) {taskHandler.pause();}break;case 2:if (pauseOnFling) {taskHandler.pause();}break;}if (externalListener != null) {externalListener.onScrollStateChanged(view, scrollState);}}@Overridepublic void onScrolled(RecyclerView recyclerView, int dx, int dy) {if (externalListener != null) {externalListener.onScrolled(recyclerView, dx, dy);}}}

本文结束.