Win8 图片uri保存到本地图片库 -- 及各种流之间的转换

已知网络上图片的uri地址，如何将网络图片保存到本地呢？代码如下：

保存图片到本地

private async Task SaveImageFromUrl(string uri, string filename)        {            var rass = RandomAccessStreamReference.CreateFromUri(new Uri(uri));            IRandomAccessStream inputStream = await rass.OpenReadAsync();            Stream input = WindowsRuntimeStreamExtensions.AsStreamForRead(inputStream.GetInputStreamAt(0));            try            {                //获取图片扩展名的Guid                StorageFolder folder = KnownFolders.PicturesLibrary;                StorageFile outputFile = await folder.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);                using (IRandomAccessStream outputStream = await outputFile.OpenAsync(FileAccessMode.ReadWrite))                {                    Stream output = WindowsRuntimeStreamExtensions.AsStreamForWrite(outputStream.GetOutputStreamAt(0));                    await input.CopyToAsync(output);                    output.Dispose();                    input.Dispose();                }            }            catch (Exception)            {            }        }

根据图片uri保存到本地的函数，即以上为图片uri和图片名称的转换，另以下三种转换：

1、FileName转换为Stream，图片可为本地图片，也可为应用程序中图片

图片转换为流

private async Task<Stream> ImageNameToStream(string filename)        {            try            {                ////本地图片库                //StorageFolder folder = KnownFolders.PicturesLibrary;//本地图片库                //StorageFile storagefile = await folder.GetFileAsync(filename);                //应用程序Images文件夹图片                Uri _baseUri = new Uri("ms-appx:///");                Uri uri = new Uri(_baseUri, "../Images/" + filename);                StorageFile storagefile = await StorageFile.GetFileFromApplicationUriAsync(uri);                IRandomAccessStream irandom = await storagefile.OpenAsync(FileAccessMode.Read);                Stream outPutstream = irandom.GetInputStreamAt(0).AsStreamForRead();                return outPutstream;            }            catch (Exception ex)            {                return null;            }        }

2、Stream转换成文件，图片保存到本地

流转换成本地图片

private async Task StreamToFileName(Stream inputstream, string filename)        {            try            {                StorageFolder folder = KnownFolders.PicturesLibrary;                StorageFile outputFile = await folder.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);                using (IRandomAccessStream output = await outputFile.OpenAsync(FileAccessMode.ReadWrite))                {                    Stream outputstream = WindowsRuntimeStreamExtensions.AsStreamForWrite(output.GetOutputStreamAt(0));                    await inputstream.CopyToAsync(outputstream);                    outputstream.Dispose();                    inputstream.Dispose();                }            }            catch (Exception ex)            {            }        }

3、图片Uri转换成流

网络图片Uri转换成流

private async Task<Stream> UriToStream(string uri)        {            var rass = RandomAccessStreamReference.CreateFromUri(new Uri(uri));            IRandomAccessStream inputStream = await rass.OpenReadAsync();            Stream input = WindowsRuntimeStreamExtensions.AsStreamForRead(inputStream.GetInputStreamAt(0));            return input;        }

若有其他流与Metro流之间的转换,参考http://www.cnblogs.com/jing870812/archive/2012/04/12/2444870.html

 

// 内容如下：

 

今天在Stream与IrandomAccessStream之间转换时，感觉很纠结，所以干脆先把想到的一些场景都罗列了一下，希望下次再用的时候就不用这么毛手毛脚的了。。。 

Stream 转IRandomAccessStream

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方法一：

byte[] bytes = StreamToBytes(stream);

InMemoryRandomAccessStream memoryStream =new InMemoryRandomAccessStream();

DataWriter datawriter =new DataWriter(memoryStream.GetOutputStreamAt(0));

datawriter.WriteBytes(bytes);

await datawriter.StoreAsync();

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方法二：

var randomAccessStream =new InMemoryRandomAccessStream();

var outputStream = randomAccessStream.GetOutputStreamAt(0);

await RandomAccessStream.CopyAsync(stream.AsInputStream(), outputStream);

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IRandomAccessStream 转 Stream

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Stream stream=WindowsRuntimeStreamExtensions.AsStreamForRead(randomStream.GetInputStreamAt(0));

 

Ibuffer转Stream

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Stream stream = WindowsRuntimeBufferExtensions.AsStream(buffer);

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Stream转Ibuffer

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MemoryStream memoryStream =new MemoryStream();           

 if(stream != null)

 {

      byte[] bytes = ReadFully(stream);

      if(bytes != null)

      {

           var binaryWriter =new BinaryWriter(memoryStream);

           binaryWriter.Write(bytes);

       }

  }

 IBuffer buffer=WindowsRuntimeBufferExtensions.GetWindowsRuntimeBuffer(memoryStream,0,(int)memoryStream.Length);

 

Ibuffer转byte[]

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byte[] bytes=WindowsRuntimeBufferExtensions.ToArray(buffer,0,(int)buffer.Length);

 

Byte[]转Ibuffer

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WindowsRuntimeBufferExtensions.AsBuffer(bytes,0,bytes.Length);

 

Ibuffer转IrandomAccessStream

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InMemoryRandomAccessStream inStream =new InMemoryRandomAccessStream();

DataWriter datawriter =new DataWriter(inStream.GetOutputStreamAt(0));

datawriter.WriteBuffer(buffer,0,buffer.Length);

await datawriter.StoreAsync();

 

IrandomAccessStream转Ibuffer

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Stream stream=WindowsRuntimeStreamExtensions.AsStreamForRead(randomStream.GetInputStreamAt(0));

MemoryStream memoryStream =new MemoryStream();           

if (stream != null)

{

    byte[] bytes = ReadFully(stream);

    if(bytes != null)

    {

        var binaryWriter =new BinaryWriter(memoryStream);

        binaryWriter.Write(bytes);

    }

}

IBuffer buffer=WindowsRuntimeBufferExtensions.GetWindowsRuntimeBuffer(memoryStream,0,(int)memoryStream.Length);

 

IRandomAccessStream转FileInputStream

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FileInputStream inputStream=randomStream.GetInputStreamAt(0)as FileInputStream;

 

IRandomAccessStream转FileOutputStream

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FileOutputStream outStream= randomStream.GetOutputStreamAt(0)as FileOutputStream;

 

Stream转byte[]

public static byte[] ConvertStreamTobyte(Stream input) 

{ 

byte[] buffer = new byte[16 * 1024]; 

using (MemoryStream ms = new MemoryStream()) 

{ 

int read; 

while ((read = input.Read(buffer, 0, buffer.Length)) > 0) 

{ 

ms.Write(buffer, 0, read); 

} 

return ms.ToArray(); 

} 

} 

  

Byte转Stream

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public Stream BytesToStream(byte[] bytes)

        {

            Stream stream =new MemoryStream(bytes);

            returnstream;

        }

 

Stream转MemoryStream

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public static MemoryStream ConvertStreamToMemoryStream(Stream stream)

        {

            MemoryStream memoryStream =new MemoryStream();

            if(stream != null)

            {

                byte[] buffer = ReadFully(stream);

                if(buffer != null)

                {

                    var binaryWriter =new BinaryWriter(memoryStream);

                    binaryWriter.Write(buffer);

                }

            }

            returnmemoryStream;

        }

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应该还有些其它的场景,目前就想到这些,绕晕了都,恩恩…