001 /*
002 // $Id: //open/mondrian/src/main/mondrian/spi/impl/FilterDynamicSchemaProcessor.java#1 $
003 // This software is subject to the terms of the Common Public License
004 // Agreement, available at the following URL:
005 // http://www.opensource.org/licenses/cpl.html.
006 // Copyright (C) 2007-2007 Julian Hyde
007 // All Rights Reserved.
008 // You must accept the terms of that agreement to use this software.
009 */
010 package mondrian.spi.impl;
011
012 import mondrian.spi.DynamicSchemaProcessor;
013 import mondrian.olap.Util;
014 import org.apache.commons.vfs.FileSystemManager;
015 import org.apache.commons.vfs.VFS;
016 import org.apache.commons.vfs.FileObject;
017 import org.apache.commons.vfs.FileContent;
018
019 import java.io.File;
020 import java.io.InputStream;
021 import java.io.BufferedReader;
022 import java.io.InputStreamReader;
023
024 /**
025 * Implementation of {@link DynamicSchemaProcessor} which allows a derived class
026 * to easily process a schema file.
027 *
028 * <p>Mondrian's default mechanism for loading schema files, if no
029 * DynamicSchemaProcessor is specified, is to use Apache VFS (virtual file
030 * system) to resolve the URL to a stream, and to read the contents of the
031 * stream into a string.
032 *
033 * <p>FilterDynamicSchemaProcessor implements exactly the
034 * same mechanism, but makes it easy for a derived class to override the
035 * mechanism. For example:<ul>
036 *
037 * <li>To redirect to a different URL, override the
038 * {@link #processSchema(String, mondrian.olap.Util.PropertyList)} method.
039 *
040 * <li>To process the contents of the URL, override the
041 * {@link #filter(String, mondrian.olap.Util.PropertyList, java.io.InputStream)}
042 * method.
043 *
044 * </ul>
045 *
046 * @author jhyde
047 * @version $Id: //open/mondrian/src/main/mondrian/spi/impl/FilterDynamicSchemaProcessor.java#1 $
048 * @since Mar 30, 2007
049 */
050 public class FilterDynamicSchemaProcessor implements DynamicSchemaProcessor {
051
052 /**
053 * {@inheritDoc}
054 *
055 * <p>FilterDynamicSchemaProcessor's implementation of this method reads
056 * from the URL supplied (that is, it does not perform URL translation)
057 * and passes it through the {@link #filter} method.
058 */
059 public String processSchema(
060 String schemaUrl,
061 Util.PropertyList connectInfo) throws Exception
062 {
063 FileSystemManager fsManager = VFS.getManager();
064 File userDir = new File("").getAbsoluteFile();
065 FileObject file = fsManager.resolveFile(userDir, schemaUrl);
066 FileContent fileContent = file.getContent();
067 return filter(schemaUrl, connectInfo, fileContent.getInputStream());
068 }
069
070 /**
071 * Reads the contents of a schema as a stream and returns the result as
072 * a string.
073 *
074 * <p>The default implementation returns the contents of the schema
075 * unchanged.
076 *
077 * @param schemaUrl the URL of the catalog
078 * @param connectInfo Connection properties
079 * @param stream Schema contents represented as a stream
080 * @return the modified schema
081 * @throws Exception if an error occurs
082 */
083 protected String filter(
084 String schemaUrl,
085 Util.PropertyList connectInfo,
086 InputStream stream)
087 throws Exception
088 {
089 BufferedReader in =
090 new BufferedReader(
091 new InputStreamReader(stream));
092 try {
093 StringBuilder builder = new StringBuilder();
094 char[] buf = new char[2048];
095 int readCount;
096 while ((readCount = in.read(buf, 0, buf.length)) >= 0) {
097 builder.append(buf, 0, readCount);
098 }
099 return builder.toString();
100 } finally {
101 in.close();
102 }
103 }
104 }
105
106 // End FilterDynamicSchemaProcessor.java