Android Loader使用时,屏幕解锁后,重复加载
jopen
9年前
在使用AsyncTaskLoader时,当手机解锁后,会重复加载数据,代码如下:
static class CouponShopQueryLoader extends AsyncTaskLoader<List<CouponStore>> { private int couponId; public CouponShopQueryLoader(Context context, int couponId) { super(context); this.couponId = couponId; } @Override protected void onStartLoading() { forceLoad(); } @Override public List<CouponStore> loadInBackground() { //查询数据加载 } }
这时候,很奇怪的现象就出来了,每次手机解锁后,数据都会重复了,重复加载。经查阅CursorLoader源码后发现,原来还是自己太嫩了,loader使用时,没有严格遵守android官方帮助文档demo的使用方式。经修改后:
static class CouponShopQueryLoader2 extends AsyncTaskLoader<List<CouponStore>> { private List<CouponStore> mData; private int couponId; public CouponShopQueryLoader2(Context context, int couponId) { super(context); this.couponId = couponId; } // final ForceLoadContentObserver mObserver; /* Runs on a worker thread */ @Override public List<CouponStore> loadInBackground() { mData = ds.queryShopByCoupon(couponId, pageNo, PAGE_SIZE); return mData; } /* Runs on the UI thread */ @Override public void deliverResult(List<CouponStore> data) { if (isReset()) { return; } if (isStarted()) { super.deliverResult(data); } } /** * Starts an asynchronous load of the contacts list data. When the * result is ready the callbacks will be called on the UI thread. If a * previous load has been completed and is still valid the result may be * passed to the callbacks immediately. * * Must be called from the UI thread */ @Override protected void onStartLoading() { if (mData != null) { deliverResult(mData); } if (takeContentChanged() || mData == null) { forceLoad(); } } /** * Must be called from the UI thread */ @Override protected void onStopLoading() { Log.d("sss", "onStopLoading"); // Attempt to cancel the current load task if possible. cancelLoad(); } @Override public void onCanceled(List<CouponStore> cursor) { Log.d("sss", "onCanceled"); } @Override protected void onReset() { super.onReset(); Log.d("sss", "onReset"); // Ensure the loader is stopped onStopLoading(); mData = null; } }
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当手机屏幕关闭时,会调用onStopLoading()方法,此时应该将loader取消掉,当屏幕解锁时,会去执行onStartLoading() 方法,在onStartLoading方法中根据数据是否需要重新加载进行判断。而如果不在onStartLoading进行loader状态判断的话, 就导致了数据重复加载的问题! ok---解决了!
来自:http://blog.csdn.net/cml_blog/article/details/40393909
/** * Must be called from the UI thread */ @Override protected void onStopLoading() { Log.d("sss", "onStopLoading"); // Attempt to cancel the current load task if possible. cancelLoad(); }
当手机屏幕关闭时,会调用onStopLoading()方法,此时应该将loader取消掉,当屏幕解锁时,会去执行onStartLoading() 方法,在onStartLoading方法中根据数据是否需要重新加载进行判断。而如果不在onStartLoading进行loader状态判断的话, 就导致了数据重复加载的问题! ok---解决了!
来自:http://blog.csdn.net/cml_blog/article/details/40393909