C# DB.Download方法代码示例

		public static void WriteToDisk (this DBWorkFile wf, DB db, string dir)
		{
			byte [] buffer = new byte [1024];
			int read;
			string filename = Path.Combine (dir, wf.filename);
			DBFile file = DBFile_Extensions.Create (db, wf.file_id);

			if (!Directory.Exists (dir))
				Directory.CreateDirectory (dir);

			using (Stream stream = db.Download (wf)) {
				using (FileStream fs = new FileStream (filename, FileMode.Create, FileAccess.Write, FileShare.Read)) {
					while (0 != (read = stream.Read (buffer, 0, buffer.Length))) {
						fs.Write (buffer, 0, read);
					}
				}
			}

			if (file.compressed_mime == "application/x-gzip")
				FileUtilities.GZUncompress (filename);
		}

		public static int CompressFiles ()
		{
			byte [] buffer = new byte [1024];
			int read;
			long saved_space = 0;

			using (DB db = new DB (true)) {
				using (DB db_save = new DB (true)) {
					using (IDbCommand cmd = db.CreateCommand ()) {
						cmd.CommandText = @"
SELECT File.*
FROM File
WHERE (File.compressed_mime = '' OR File.compressed_mime IS NULL) 
	AND File.size <> 0 
	AND File.id IN 
		(SELECT WorkFile.file_id FROM WorkFile WHERE WorkFile.file_id = File.id)
LIMIT 10 
";
						using (IDataReader reader = cmd.ExecuteReader ()) {
							while (reader.Read ()) {
								DBFile file = new DBFile (reader);
								long srclength;
								long destlength = -1;
								string tmpfile = Path.GetTempFileName ();
								string tmpfilegz;

								Console.Write ("Downloading {0} = {1} with size {2}... ", file.id, file.filename, file.size);

								using (Stream stream_reader = db_save.Download (file)) {
									using (FileStream stream_writer = new FileStream (tmpfile, FileMode.Create, FileAccess.Write)) {
										while (0 < (read = stream_reader.Read (buffer, 0, buffer.Length))) {
											stream_writer.Write (buffer, 0, read);
										}
									}
								}

								srclength = new FileInfo (tmpfile).Length;
								Console.Write ("Compressing file {0} with size {1}... ", tmpfile, srclength);

								tmpfilegz = FileUtilities.GZCompress (tmpfile);

								if (tmpfilegz == null) {
									Console.WriteLine ("Compression didn't succeed.");
								} else {
									destlength = new FileInfo (tmpfilegz).Length;
									Console.WriteLine ("Success, compressed size: {0} ({1}%)", destlength, 100 * (double) destlength / (double) srclength);

									using (IDbTransaction transaction = db_save.BeginTransaction ()) {
										// Upload the compressed file. 
										// Npgsql doesn't seem to have a way to truncate a large object,
										// so we just create a new large object and delete the old one.
										int file_id = file.file_id.Value;
										int gzfile_id = db_save.Manager.Create (LargeObjectManager.READWRITE);
										LargeObject gzfile = db_save.Manager.Open (gzfile_id, LargeObjectManager.READWRITE);

										using (FileStream st = new FileStream (tmpfilegz, FileMode.Open, FileAccess.Read, FileShare.Read)) {
											while (0 < (read = st.Read (buffer, 0, buffer.Length)))
												gzfile.Write (buffer, 0, read);
										}
										gzfile.Close ();

										// Save to our File record
										file.file_id = gzfile_id;
										file.compressed_mime = "application/x-gzip";
										file.Save (db_save);

										// Delete the old large object
										db_save.Manager.Delete (file_id);

										transaction.Commit ();

										saved_space += (srclength - destlength);
									}
								}

								if (File.Exists (tmpfilegz)) {
									try {
										File.Delete (tmpfilegz);
									} catch {
										// Ignore
									}
								}
								if (File.Exists (tmpfile)) {
									try {
										File.Delete (tmpfile);
									} catch {
										// Ignore
									}
								}
							}
						}
						//}
					}
				}
			}

			Console.WriteLine ("Saved {0} bytes.", saved_space);

			return 0;
		}

		public static int MoveFilesToFileSystem ()
		{
			long moved_bytes = 0;

			Manager.log.Info ("MoveFilesToFileSystem: [START]");

			using (DB db = new DB ()) {
				using (DB download_db = new DB ()) {
					while (true) {
						using (IDbCommand cmd = db.CreateCommand ()) {
							// execute this in chunks to avoid huge data transfers and slowdowns.
							cmd.CommandText = "SELECT * FROM File WHERE NOT file_id IS NULL LIMIT 100";
							using (IDataReader reader = cmd.ExecuteReader ()) {
								if (!reader.Read ())
									break;

								do {
									DBFile file = new DBFile (reader);
									byte [] buffer = new byte [1024];
									int oid = file.file_id.Value;
									int read;
									string fn = FileUtilities.CreateFilename (file.md5, file.compressed_mime == MimeTypes.GZ, true);
									using (FileStream writer = new FileStream (fn, FileMode.Create, FileAccess.Write, FileShare.Read)) {
										using (Stream str = download_db.Download (file)) {
											while ((read = str.Read (buffer, 0, buffer.Length)) != 0)
												writer.Write (buffer, 0, read);
										}
									}

									IDbTransaction transaction = download_db.BeginTransaction ();
									download_db.Manager.Delete (oid);
									file.file_id = null;
									file.Save (download_db);
									transaction.Commit ();

									moved_bytes += file.size;
									log.InfoFormat ("MoveFilesToFileSystem: Moved oid {0} to {1} ({2} bytes, {3} total bytes moved)", oid, fn, file.size, moved_bytes);
								} while (reader.Read ());
							}
						}
					}

					while (true) {
						using (IDbCommand cmd = db.CreateCommand ()) {
							// execute this in chunks to avoid huge data transfers and slowdowns.
							cmd.CommandText = "SELECT * FROM Revision WHERE (diff_file_id IS NULL AND NOT diff = '') OR (log_file_id IS NULL AND NOT log = '') LIMIT 100";
							using (IDataReader reader = cmd.ExecuteReader ()) {
								if (!reader.Read ())
									break;

								do {
									DBRevision revision = new DBRevision (reader);
									string tmpfile = null;

									if (!string.IsNullOrEmpty (revision.diff)) {
										int length = 0;
										if (revision.diff_file_id == null) {
											try {
												length = revision.diff.Length;
												tmpfile = Path.GetTempFileName ();
												File.WriteAllText (tmpfile, revision.diff);
												DBFile diff = download_db.Upload (tmpfile, ".log", false, null);
												revision.diff_file_id = diff.id;
												revision.diff = null;
											} finally {
												try {
													if (File.Exists (tmpfile))
														File.Delete (tmpfile);
												} catch (Exception ex) {
													log.ErrorFormat ("error deleting temp file: {0}", ex);
												}
											}
											moved_bytes += length;
											log.InfoFormat ("MoveFilesToFileSystem: Moved revision {0}'s diff to db/filesystem ({1} bytes, {2} total bytes moved)", revision.id, length, moved_bytes);
										}
									}

									if (!string.IsNullOrEmpty (revision.log)) {
										int length = 0;
										if (revision.log_file_id == null) {
											try {
												length = revision.log.Length;
												tmpfile = Path.GetTempFileName ();
												File.WriteAllText (tmpfile, revision.log);
												DBFile log = download_db.Upload (tmpfile, ".log", false, null);
												revision.log_file_id = log.id;
												revision.log = null;
											} finally {
												try {
													if (File.Exists (tmpfile))
														File.Delete (tmpfile);
												} catch (Exception ex) {
													log.ErrorFormat ("error deleting temp file: {0}", ex);
												}
											}
											moved_bytes += length;
											Manager.log.InfoFormat ("MoveFilesToFileSystem: Moved revision {0}'s log to db/filesystem ({1} bytes, {2} total bytes moved)", revision.id, length, moved_bytes);
										}
										revision.log = null;
									}
//.........这里部分代码省略.........

		private void DownloadWorkFile (int workfile_id, string md5)
		{
			DBWorkFileView view = null;
			DBFile file = null;
			string filename;
			string mime;
			string compressed_mime;

			using (DB db = new DB ()) {
				WebServiceLogin login = Authentication.CreateLogin (Request);

				filename = Request ["filename"];

				if (!string.IsNullOrEmpty (md5)) { // md5 lookup needs admin rights
					Authentication.VerifyUserInRole (Context, db, login, Roles.Administrator, false);
					file = DBFile_Extensions.Find (db, md5);

					if (file == null)
						throw new HttpException (404, "Could not find the file.");

					mime = file.mime;
					filename = file.filename;
					compressed_mime = file.compressed_mime;
				} else {
					view = DBWorkFileView_Extensions.Find (db, workfile_id);

					if (view == null)
						throw new HttpException (404, "Could not find the file.");

					if ([email protected]) // internal files need admin rights
						Authentication.VerifyUserInRole (Context, db, login, Roles.Administrator, false);
					else
						Authentication.VerifyAnonymousAccess (Context, db, login);

					if (!string.IsNullOrEmpty (filename)) {
						file = DBWork_Extensions.GetFile (db, view.work_id, filename, false);
						if (file == null)
							throw new HttpException (404, string.Format ("Could not find the filename '{0}'", filename));

						mime = file.mime;
						compressed_mime = file.compressed_mime;
						md5 = file.md5;

						view = null;
					} else {
						mime = view.mime;
						filename = view.filename;
						compressed_mime = view.compressed_mime;
					}
				}

				Response.ContentType = mime;
				Response.AppendHeader ("Content-Disposition", "filename=\"" + Path.GetFileName (filename) + "\"");

				// any access rights verified, serve the file

				if (view != null) {
					if (view.file_file_id == null) {
						DownloadMd5 (view.md5);
					} else {
						using (Stream str = db.Download (view)) {
							DownloadStream (str, compressed_mime);
						}
					}
				} else {
					DownloadFile (db, file);
				}
			}
		}

		private void DownloadFile (DB db, DBFile file)
		{
			// access must be verified before calling this method (no verification is done here)
			if (file.file_id == null) {
				DownloadMd5 (file.md5);
			} else {
				using (Stream str = db.Download (file)) {
					DownloadStream (str, file.compressed_mime);
				}
			}
		}