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2 * Licensed to the Apache Software Foundation (ASF) under one *
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4 * distributed with this work for additional information *
5 * regarding copyright ownership. The ASF licenses this file *
6 * to you under the Apache License, Version 2.0 (the *
7 * "License"); you may not use this file except in compliance *
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10 * http://www.apache.org/licenses/LICENSE-2.0 *
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14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY *
15 * KIND, either express or implied. See the License for the *
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19
20 package org.apache.james.context;
21
22 import org.apache.avalon.framework.context.Context;
23 import org.apache.avalon.framework.context.ContextException;
24
25 import java.io.File;
26 import java.io.IOException;
27
28 /***
29 * This class is essentially a set of static functions for
30 * extracting information from the Avalon context. This class
31 * should never be instantiated. Each function takes the context
32 * as a first argument.
33 */
34 public class AvalonContextUtilities {
35
36 /***
37 * The file URL prefix
38 */
39 private static String filePrefix = "file://";
40
41 /***
42 * The file URL prefix length
43 */
44 private static int filePrefixLength = filePrefix.length();
45
46 /***
47 * Gets the file or directory described by the argument file URL.
48 *
49 * @param context the Avalon context
50 * @param fileURL an appropriately formatted URL describing a file on
51 * the filesystem on which the server is running. The
52 * URL is evaluated as a location relative to the
53 * application home, unless it begins with a slash. In
54 * the latter case the file location is evaluated relative
55 * to the underlying file system root.
56 *
57 * @throws IllegalArgumentException if the arguments are null or the file
58 * URL is not appropriately formatted.
59 * @throws ContextException if the underlying context generates a
60 * ContextException, if the application home is
61 * not correct, or if an IOException is generated
62 * while accessing the file.
63 */
64 public static File getFile(Context context, String fileURL)
65 throws Exception {
66 if ((context == null) || (fileURL == null)) {
67 throw new IllegalArgumentException("The getFile method doesn't allow null arguments.");
68 }
69 String internalFileURL = fileURL.trim();
70 if (!(internalFileURL.startsWith(filePrefix))) {
71 throw new IllegalArgumentException("The fileURL argument to getFile doesn't start with the required file prefix - " + filePrefix);
72 }
73
74 String fileName = fileURL.substring(filePrefixLength);
75 if (!(fileName.startsWith("/"))) {
76 String baseDirectory = "";
77 try {
78 File applicationHome =
79 (File)context.get(AvalonContextConstants.APPLICATION_HOME);
80 baseDirectory = applicationHome.toString();
81 } catch (ContextException ce) {
82 throw new ContextException("Encountered exception when resolving application home in Avalon context.", ce);
83 } catch (ClassCastException cce) {
84 throw new ContextException("Application home object stored in Avalon context was not of type java.io.File.", cce);
85 }
86 StringBuffer fileNameBuffer =
87 new StringBuffer(128)
88 .append(baseDirectory)
89 .append(File.separator)
90 .append(fileName);
91 fileName = fileNameBuffer.toString();
92 }
93 try {
94 File returnValue = (new File(fileName)).getCanonicalFile();
95 return returnValue;
96 } catch (IOException ioe) {
97 throw new ContextException("Encountered an unexpected exception while retrieving file.", ioe);
98 }
99 }
100
101 /***
102 * Private constructor to ensure that instances of this class aren't
103 * instantiated.
104 */
105 private AvalonContextUtilities() {}
106 }