Android的SDK天青 - 当我尝试加载从Blob存储东西的NullPointerException [英] Android Azure SDK - NullPointerException when I try to load something from blob storage

问题描述

我创建在Azure上的容器被称为assetcontainer。

I've created a container on Azure called 'assetcontainer'.

我已经按照样品创建以下code：

I've followed the sample to create the following code:

 CloudStorageAccount account = CloudStorageAccount.parse(BuildConfig.AzureConnectionString);
        mClient = account.createCloudBlobClient();
        mAssetContainer = mClient.getContainerReference("assetcontainer");


        // Download the blob
        // For each item in the container
        for (ListBlobItem blobItem : mAssetContainer.listBlobs()) {
            // If the item is a blob, not a virtual directory
            if (blobItem instanceof CloudBlockBlob) {
                // Download the text
                CloudBlockBlob retrievedBlob = (CloudBlockBlob) blobItem;

                try {
                    retrievedBlob.download(new FileOutputStream(mContext.getFilesDir() + "\\assets\\" + ((CloudBlockBlob) blobItem).getName()));
                }
                catch(Exception ex){}
            }
        }

和我收到以下异常，当我尝试遍历listBlobs（）：

And I am receiving the following exception when I try to iterate the listBlobs():

Process: com.training.app.debug, PID: 3284
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.training.app.debug/com.training.app.activities.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2292)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2350)
            at android.app.ActivityThread.access$800(ActivityThread.java:163)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1257)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5335)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.android.okhttp.internal.http.HttpEngine.readResponse(HttpEngine.java:783)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:347)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:296)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponseCode(HttpURLConnectionImpl.java:503)
            at com.microsoft.azure.storage.StorageException.translateException(StorageException.java:145)
            at com.microsoft.azure.storage.core.ExecutionEngine.executeWithRetry(ExecutionEngine.java:252)
            at com.microsoft.azure.storage.core.LazySegmentedIterator.hasNext(LazySegmentedIterator.java:109)
            at com.training.azure.AzureStorage.syncAssets(AzureStorage.java:57)
            at com.training.app.activities.MainActivity.onCreate(MainActivity.java:52)
            at android.app.Activity.performCreate(Activity.java:5389)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2256)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2350)
            at android.app.ActivityThread.access$800(ActivityThread.java:163)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1257)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5335)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)

我不知道这可能是错在这里...这是湛蓝的SDK中的错误？

I'm not sure what could be wrong here... Is this a bug with the azure sdk?

推荐答案

我发现从的此页面，它为我工作。

I found a solution from this page, and it worked for me.

Android的不允许在主线程中执行网络操作，所以你需要在一个异步任务执行code，是这样的：

Android doesn't allow performing network operations in the main thread, so you need to execute the code in an asynchronous task, like this:

private class MyTask extends AsyncTask<Void, Void, Void>{
 @Override
protected Void doInBackground(Void... params) {
    CloudStorageAccount account = CloudStorageAccount.parse(BuildConfig.AzureConnectionString);
    mClient = account.createCloudBlobClient();
    mAssetContainer = mClient.getContainerReference("assetcontainer");


    // Download the blob
    // For each item in the container
    for (ListBlobItem blobItem : mAssetContainer.listBlobs()) {
        // If the item is a blob, not a virtual directory
        if (blobItem instanceof CloudBlockBlob) {
            // Download the text
            CloudBlockBlob retrievedBlob = (CloudBlockBlob) blobItem;

            try {
                retrievedBlob.download(new FileOutputStream(mContext.getFilesDir() + "\\assets\\" + ((CloudBlockBlob) blobItem).getName()));
            }
            catch(Exception ex){}
        }
    }
}
}

然后调用新MyTask（）的execute（）在主线程。

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