在使用IsolatedStorageFile时的一点问题

Question

在PhotoChooserTask对象的Completed事件里，我用IsolatedStorageFile实例化一个名为isf的对象，然后用FileExists方法判断名为"a.jpg"的图像是否存在与独立文件中，如果存在就用DeleteFile方法删除，然后根据选择的图片重新创建一个名为a.jpg的图像。代码如下：       

void photoChooserTask_Completed(object sender, PhotoResult e)
        {
            if (e.TaskResult == TaskResult.OK)
            {
                WriteableBitmap bmp = new WriteableBitmap(435, 435);
                bmp.SetSource(e.ChosenPhoto);
                if (isf.FileExists("a.jpg"))
                {
                    isf.DeleteFile("a.jpg");
                }
                using (Stream stream = isf.OpenFile("a.jpg", FileMode.OpenOrCreate))
                {
                    Extensions.SaveJpeg(bmp, stream, 435, 435, 0, 100);
                }
                imageMain.Source = bmp;
            }
        }

代码执行到isf.DeleteFile("a.jpg");报错An error occurred while accessing IsolatedStorage.

各位牛人们，求解啊····

Answer 1

你好，

是不是文件路径的设置问题。

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Keep Fighting

Answer 2

你好，这个不是路径的问题。我在创建a.jpg的时候直接放在独立存储里面的，没有选择新的路径，所以应该不是。

Answer 3

能否给出isf的定义方法，以及a.jpg的保存方法，然后进一步分析问题的原因。

---

Xuesong

Answer 4

IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication(); //isf定义

//保存图片

WriteableBitmap bmp = new WriteableBitmap(435, 435);
bmp.SetSource(e.ChosenPhoto);

using (Stream stream = isf.OpenFile("Puzzle.jpg", FileMode.OpenOrCreate))
{
     Extensions.SaveJpeg(bmp, stream, 435, 435, 0, 100);
}

Answer 5

你好,我尝试了你的代码,运行并没有问题.

因为你报出的错误是An error occurred while accessing IsolatedStorage.似乎是Stream并没有通向IsolatedStorage

我对于你的代码进行了修改,希望你可以尝试下:

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <Button Content="Save" Height="72" HorizontalAlignment="Left" Margin="10,10,0,0" Name="button1" VerticalAlignment="Top" Width="160" Click="Save_Click" />
            <Button Content="Load" Height="72" HorizontalAlignment="Left" Margin="160,10,0,0" Name="button2" VerticalAlignment="Top" Width="160" Click="Load_Click" />
            <Image Height="244" HorizontalAlignment="Left" Margin="12,88,0,0" Name="image1" Stretch="Fill" VerticalAlignment="Top" Width="438" />
            <Image Height="244" HorizontalAlignment="Left" Margin="12,338,0,0" Name="image2" Stretch="Fill" VerticalAlignment="Top" Width="438" />
        </Grid>

 private void Save_Click(object sender, RoutedEventArgs e)
        {
            PhotoChooserTask task = new PhotoChooserTask();
            task.Completed += new EventHandler<PhotoResult>(task_Completed);
            task.Show();
        }
 
        void task_Completed(object sender, PhotoResult e)
        {
 
            if (e.TaskResult == TaskResult.OK)
            {
                IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication(); 
                WriteableBitmap bmp = new WriteableBitmap(435, 435);
                bmp.SetSource(e.ChosenPhoto);
                if (isf.FileExists("a.jpg"))
                {
                    isf.DeleteFile("a.jpg");
                }
                using (IsolatedStorageFileStream isfs = new IsolatedStorageFileStream("a.jpg",FileMode.Create,isf))
                {
                    Extensions.SaveJpeg(bmp, isfs, 435, 435, 0, 100);
                    isfs.Flush();
                }
                image1.Source = bmp;
            }
        }
 
        private void Load_Click(object sender, RoutedEventArgs e)
        {
            IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication();
            WriteableBitmap bmp = new WriteableBitmap(435, 435);
            if (isf.FileExists("a.jpg"))
            {
                using (IsolatedStorageFileStream isfs = new IsolatedStorageFileStream("a.jpg", FileMode.Open, isf))
                {
                    Extensions.LoadJpeg(bmp, isfs);
                    isfs.Flush();
                }
            }
            image2.Source = bmp;
        }

Answer 6

这里我使用了IsolatedStorageFileStream 代替Stream

Answer 7

好的 谢谢。