monetdb-java: src/main/java/org/monetdb/jdbc/MonetConnection.java comparison

comparison src/main/java/org/monetdb/jdbc/MonetConnection.java @ 576:095e896f9d7a onclient

Updated comments. Improved code. Added final keywords

author	Martin van Dinther <martin.van.dinther@monetdbsolutions.com>
date	Wed, 06 Oct 2021 22:48:11 +0200 (2021-10-06)
parents	b4d29515c22e
children	72f4437de9be

comparison

equal deleted inserted replaced

-:08c9918177b2
+:095e896f9d7a
 * whole Connection interface.
 *</pre>
 *
 * @author Fabian Groffen
 * @author Martin van Dinther
-* @version 1.6
+* @version 1.7
 */
 public class MonetConnection
 	extends MonetWrapper
 	implements Connection, AutoCloseable
 {
 	@Override
 	public java.sql.Array createArrayOf(final String typeName, final Object[] elements) throws SQLException {
 		throw newSQLFeatureNotSupportedException("createArrayOf");
 	}
 	/**
 	 * Constructs an object that implements the Clob interface. The
 	 * object returned initially contains no data. The setAsciiStream,
 	 * setCharacterStream and setString methods of the Clob interface
 	 * may be used to add data to the Clob.
 	//== end methods of interface java.sql.Connection
 	//== internal helper methods which do not belong to the JDBC interface
-	/** Handlers for ON CLIENT requests */
+	/** Handler for COPY ... INTO ... FROM 'data-file-name' ON CLIENT requests */
 	private UploadHandler uploadHandler;
+	/** Handler for COPY ... INTO 'data-file-name' ON CLIENT requests */
 	private DownloadHandler downloadHandler;
 	/**
 	 * Registers a {@link UploadHandler} to support for example COPY INTO mytable FROM 'data.csv' ON CLIENT
 	 *
 	 * @param uploadHandler the handler to register, or null to deregister
 	 */
-	public void setUploadHandler(UploadHandler uploadHandler) {
+	public void setUploadHandler(final UploadHandler uploadHandler) {
 		this.uploadHandler = uploadHandler;
 	}
 	/**
 	 * Returns the currently registerered {@link UploadHandler}, or null
 	 */
 	public UploadHandler getUploadHandler() {
 		return uploadHandler;
 	}
 	/**
 	 * Registers a {@link DownloadHandler} to support for example COPY select_result INTO 'data.csv' ON CLIENT
 	 *
 	 * @param downloadHandler the handler to register, or null to deregister
 	 */
-	public void setDownloadHandler(DownloadHandler downloadHandler) {
+	public void setDownloadHandler(final DownloadHandler downloadHandler) {
 		this.downloadHandler = downloadHandler;
 	}
 	/**
 	 * Returns the currently registerered {@link DownloadHandler} handler, or null
 						curReplySize = size;
 					}
 					// }}} set reply size
 					// send query to the server
-					String queryLine = templ[0] + query + templ[1];
+					out.writeLine(templ[0] + query + templ[1]);
-					out.writeLine(queryLine);
 					// go for new results
 					String tmpLine = in.readLine();
 					LineType linetype = in.getLineType();
 					Response res = null;
 			}
 		}
 	}
 	// }}}
-	private String handleTransfer(String transferCommand) throws IOException {
+	private String handleTransfer(final String transferCommand) throws IOException {
 		if (transferCommand.startsWith("r ")) {
-			String[] parts = transferCommand.split(" ", 3);
+			final String[] parts = transferCommand.split(" ", 3);
 			if (parts.length == 3) {
 				final long offset;
 				try {
 					offset = Long.parseLong(parts[1]);
 				} catch (NumberFormatException e) {
 			return handleDownload(transferCommand.substring(2));
 		}
 		return "JDBC does not support this file transfer yet: " + transferCommand;
 	}
-	private String handleUpload(String path, boolean textMode, long offset) throws IOException {
+	private String handleUpload(final String path, final boolean textMode, final long offset) throws IOException {
 		if (uploadHandler == null) {
 			return "No file upload handler has been registered with the JDBC driver";
 		}
-		long linesToSkip = offset >= 1 ? offset - 1 : 0;
+		final long linesToSkip = offset >= 1 ? offset - 1 : 0;
-		Upload handle = new Upload(server, uploadHandler::uploadCancelled);
+		final Upload handle = new Upload(server, uploadHandler::uploadCancelled);
-		boolean wasFaking = server.setInsertFakePrompts(false);
+		final boolean wasFaking = server.setInsertFakePrompts(false);
 		try {
 			uploadHandler.handleUpload(handle, path, textMode, linesToSkip);
 			if (!handle.hasBeenUsed()) {
-				String message = "Call to " + uploadHandler.getClass().getCanonicalName() + ".handleUpload for path '" + path + "' sent neither data nor an error message";
+				throw new IOException("Call to " + uploadHandler.getClass().getCanonicalName() + ".handleUpload for path '" + path + "' sent neither data nor an error message");
-				throw new IOException(message);
 			}
 			handle.close();
 		} finally {
 			server.setInsertFakePrompts(wasFaking);
 		}
 		return handle.getError();
 	}
-	private String handleDownload(String path) throws IOException {
+	private String handleDownload(final String path) throws IOException {
 		if (downloadHandler == null) {
 			return "No file download handler has been registered with the JDBC driver";
 		}
-		Download handle = new Download(server);
+		final Download handle = new Download(server);
 		try {
 			downloadHandler.handleDownload(handle, path, true);
 			if (!handle.hasBeenUsed()) {
-				String message = "Call to " + downloadHandler.getClass().getSimpleName() + ".handleDownload sent neither data nor error";
+				handle.sendError("Call to " + downloadHandler.getClass().getSimpleName() + ".handleDownload sent neither data nor error");
-				handle.sendError(message);
 			}
 		} finally {
 			handle.close();
 		}
 		return handle.getError();
 	}
 	/**
-	 * Callback for sending files for COPY ON CLIENT
+	 * Callback for sending files for COPY INTO "table" FROM 'file-name' ON CLIENT commands
 	 *
 	 * To be registered with {@link MonetConnection#setUploadHandler(UploadHandler)}
+	 *
+	 * An example implementation can be found at ../util/FileTransferHandler.java
 	 */
 	public interface UploadHandler {
 		/**
 		 * Called if the server sends a request to read file data.
 		 */
 		default void uploadCancelled() {}
 	}
 	/**
-	 * Callback for receiving files with COPY ON CLIENT
+	 * Callback for receiving files from COPY .. INTO 'file-name' ON CLIENT commands
 	 *
 	 * To be registered with {@link MonetConnection#setDownloadHandler(DownloadHandler)}
+	 *
+	 * An example implementation can be found at ../util/FileTransferHandler.java
 	 */
 	public interface DownloadHandler {
 		/**
 		 * Called if the server sends a request to write a file.
 		 *
 		 * This method can only be sent if no data has been sent to the server
 		 * yet. After data has been sent, you can still throw an
 		 * {@link IOException} but this will terminate the connection.
 		 * @param errorMessage error message to send
 		 */
-		public void sendError(String errorMessage) throws IOException {
+		public void sendError(final String errorMessage) throws IOException {
 			if (error != null) {
 				throw new IOException("another error has already been sent: " + error);
 			}
 			error = errorMessage;
 		}
 		/**
 		 * After every {@code chunkSize} bytes, the server gets the opportunity to
 		 * terminate the upload.
 		 */
-		public void setChunkSize(int chunkSize) {
+		public void setChunkSize(final int chunkSize) {
 			this.customChunkSize = chunkSize;
 		}
 		/**
 		 * Get a {@link PrintStream} to write data to.
 			if (error != null) {
 				throw new IOException("Cannot send data after an error has been sent");
 			}
 			if (print == null) {
 				try {
-					MapiSocket.UploadStream up = customChunkSize >= 0 ? server.uploadStream(customChunkSize) : server.uploadStream();
+					final MapiSocket.UploadStream up = customChunkSize >= 0 ? server.uploadStream(customChunkSize) : server.uploadStream();
 					up.setCancellationCallback(cancellationCallback);
 					print = new PrintStream(up, false, "UTF-8");
 					up.write('\n');
 				} catch (UnsupportedEncodingException e) {
 					throw new RuntimeException("The system is guaranteed to support the UTF-8 encoding but apparently it doesn't", e);
 		/**
 		 * Read from the given input stream and write it to the server.
 		 *
 		 * For text mode uploads, the data MUST be validly UTF-8 encoded.
 		 */
-		public void uploadFrom(InputStream inputStream) throws IOException {
+		public void uploadFrom(final InputStream inputStream) throws IOException {
-			OutputStream s = getStream();
+			final OutputStream s = getStream();
-			byte[] buffer = new byte[64 * 1024];
+			final byte[] buffer = new byte[64 * 1024];
 			while (true) {
 				int nread = inputStream.read(buffer);
 				if (nread < 0) {
 					break;
 				}
 		 * Read data from the given buffered reader and send it to the server
 		 * @param reader reader to read from
 		 * @param linesToSkip start uploading at line {@code offset}. Value 0 and 1
 		 * both mean upload the whole file, value 2 means skip the first line, etc.q
 		 */
-		public void uploadFrom(BufferedReader reader, long linesToSkip) throws IOException {
+		public void uploadFrom(final BufferedReader reader, final long linesToSkip) throws IOException {
 			for (int i = 0; i < linesToSkip; i++) {
 				String line = reader.readLine();
 				if (line == null) {
 					return;
 				}
 			}
 			uploadFrom(reader);
 		}
 		/**
 		 * Read data from the given buffered reader and send it to the server
 		 * @param reader reader to read from
 		 */
-		public void uploadFrom(Reader reader) throws IOException {
+		public void uploadFrom(final Reader reader) throws IOException {
-			OutputStream s = getStream();
+			final OutputStream s = getStream();
-			OutputStreamWriter writer = new OutputStreamWriter(s, StandardCharsets.UTF_8);
+			final OutputStreamWriter writer = new OutputStreamWriter(s, StandardCharsets.UTF_8);
-			char[] buffer = new char[64 * 1024];
+			final char[] buffer = new char[64 * 1024];
 			while (true) {
 				int nread = reader.read(buffer, 0, buffer.length);
 				if (nread < 0) {
 					break;
 				}
 				writer.write(buffer, 0, nread);
 				writer.close();
 			}
 		}
+		/**
+		 * Close opened {@link PrintStream}.
+		 */
 		public void close() {
 			if (print != null) {
 				print.close();
+				print = null;
 			}
 		}
 	}
 	/**
 	public static class Download {
 		private final MapiSocket server;
 		private MapiSocket.DownloadStream stream = null;
 		private String error = null;
-		boolean closed = false;
 		Download(MapiSocket server) {
 			this.server = server;
 		}
 		/**
 		}
 		/**
 		 * Write the data from the server to the given {@link OutputStream}.
 		 */
-		public void downloadTo(OutputStream stream) throws IOException {
+		public void downloadTo(final OutputStream stream) throws IOException {
-			InputStream s = getStream();
+			final InputStream s = getStream();
-			byte[] buffer = new byte[65536];
+			final byte[] buffer = new byte[65536];
 			while (true) {
 				int nread = s.read(buffer);
-				if (nread < 0)
+				if (nread < 0) {
 					break;
+				}
 				stream.write(buffer, 0, nread);
 			}
 		}
 		/**
 		 * @return  true if data has been received or an error has been sent.
 		 */
 		public boolean hasBeenUsed() {
 			return error != null || stream != null;
 		}
 		/**
 		 * @return the error that was sent, if any
 		 */
 		public String getError() {
 			return error;
 		}
-		public void close() throws IOException {
-			if (closed) {
+		/**
-				return;
+		 * Close opened stream.
-			}
+		 */
+		public void close() {
 			if (stream != null) {
-				stream.close();
+				try {
-			}
+					stream.close();
-			closed = true;
+					stream = null;
+				} catch (IOException e) {
+					/* ignore close error */
+				}
+			}
 		}
 	}
 }

Mercurial > hg > monetdb-java

comparison src/main/java/org/monetdb/jdbc/MonetConnection.java @ 576:095e896f9d7a onclient