public override void Write(Stream outputStream, ICacheItem cacheItem)
{
PictureCacheItem pci = (PictureCacheItem)cacheItem;
StringBuilder output = new StringBuilder();
output.Append(pci.url + "\n");
output.Append(pci.creationTime.Ticks + "\n");
output.Append(pci.filename + "\n");
output.Append(pci.fileSize + "\n");
Utils.WriteString(outputStream, output.ToString());
}
public override ICacheItem Read(Stream inputStream)
{
string s = Utils.ReadString(inputStream);
string[] chunks = s.Split('\n');
string url = chunks[0];
DateTime creationTime = new DateTime(long.Parse(chunks[1]));
string filename = chunks[2];
long fileSize = long.Parse(chunks[3]);
PictureCacheItem pci = new PictureCacheItem();
pci.url = url;
pci.creationTime = creationTime;
pci.filename = filename;
pci.fileSize = fileSize;
return(pci);
}
/// <summary>
/// Downloads the picture from a internet and transfers it to a stream object.
/// </summary>
/// <param name="url">The url of the image to download.</param>
/// <returns>A <see cref="Stream"/> object containing the downloaded picture.</returns>
/// <remarks>
/// The method checks the download cache first to see if the picture has already
/// been downloaded and if so returns the cached image. Otherwise it goes to the internet for the actual
/// image.
/// </remarks>
public System.IO.Stream DownloadPicture(string url)
{
const int BUFFER_SIZE = 1024 * 10;
PictureCacheItem cacheItem = (PictureCacheItem) Cache.Downloads[url];
if (cacheItem != null)
{
return new FileStream(cacheItem.filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
}
PictureCacheItem picCache = new PictureCacheItem();
picCache.filename = Path.Combine(Cache.CacheLocation,Guid.NewGuid().ToString());
Stream read = DoDownloadPicture(url);
Stream write = new FileStream(picCache.filename, FileMode.Create, FileAccess.Write, FileShare.None);
byte[] buffer = new byte[BUFFER_SIZE];
int bytes = 0;
long fileSize = 0;
while( (bytes = read.Read(buffer, 0, BUFFER_SIZE)) > 0 )
{
fileSize += bytes;
write.Write(buffer, 0, bytes);
}
read.Close();
write.Close();
picCache.url = url;
picCache.creationTime = DateTime.UtcNow;
picCache.fileSize = fileSize;
Cache.Downloads.Shrink(Math.Max(0, Cache.CacheSizeLimit - fileSize));
Cache.Downloads[url] = picCache;
return new FileStream(picCache.filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
}
public override ICacheItem Read(Stream inputStream)
{
string s = Utils.ReadString(inputStream);
string[] chunks = s.Split('\n');
string url = chunks[0];
DateTime creationTime = new DateTime(long.Parse(chunks[1]));
string filename = chunks[2];
long fileSize = long.Parse(chunks[3]);
PictureCacheItem pci = new PictureCacheItem();
pci.url = url;
pci.creationTime = creationTime;
pci.filename = filename;
pci.fileSize = fileSize;
return pci;
}