1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.vfs2.operations;
18
19 import java.util.ArrayList;
20 import java.util.Collection;
21
22 import org.apache.commons.vfs2.FileObject;
23 import org.apache.commons.vfs2.FileSystemException;
24
25 /**
26 *
27 * @since 0.1
28 */
29 public abstract class AbstractFileOperationProvider implements FileOperationProvider {
30
31 /**
32 * Available operations. Operations could be registered for different schemes. Some operations can work only for
33 * "file" scheme, other - for "svnhttp(s)", "svn", "svnssh", but not for "file", etc. The Map has scheme as a key
34 * and Collection of operations that are available for that scheme.
35 */
36 private final Collection<Class<? extends FileOperation>> operations = new ArrayList<>();
37
38 /**
39 * Gather available operations for the specified FileObject and put them into specified operationsList.
40 *
41 * @param operationsList the list of available operations for the specified FileObject. The operationList contains
42 * classes of available operations, e.g. Class objects.
43 * @param file the FileObject for which we want to get the list of available operations.
44 * @throws FileSystemException if list of operations cannot be retrieved.
45 */
46 @Override
47 public final void collectOperations(final Collection<Class<? extends FileOperation>> operationsList,
48 final FileObject file) throws FileSystemException {
49 doCollectOperations(operations, operationsList, file);
50 }
51
52 /**
53 * Gather available operations for the specified FileObject and put them into specified operationsList.
54 *
55 * @param availableOperations the list of available operations for the specified FileObject.
56 * @param resultList List to be filled with applicable operations.
57 * @param file the FileObject for which we want to get the list of available operations.
58 * @throws FileSystemException if list of operations cannot be retrieved.
59 * @see #collectOperations(Collection operationsList, FileObject file)
60 */
61 protected abstract void doCollectOperations(final Collection<Class<? extends FileOperation>> availableOperations,
62 final Collection<Class<? extends FileOperation>> resultList, final FileObject file)
63 throws FileSystemException;
64
65 /**
66 * @param file the FileObject for which we need a operation.
67 * @param operationClass the Class which instance we are needed.
68 * @return the required operation instance.
69 * @throws FileSystemException if operation cannot be retrieved.
70 */
71 @Override
72 public final FileOperation getOperation(final FileObject file, final Class<? extends FileOperation> operationClass)
73 throws FileSystemException {
74 return instantiateOperation(file, lookupOperation(operationClass));
75 }
76
77 /**
78 * Get operation instance for specified FileOperation subclass.
79 *
80 * @param file the file this operation should act on.
81 * @param operationClass the class of an file operation interface to instantiate.
82 * @return a new file operation
83 * @throws FileSystemException if operation cannot be instantiated.
84 */
85 protected abstract FileOperation instantiateOperation(final FileObject file,
86 final Class<? extends FileOperation> operationClass) throws FileSystemException;
87
88 /**
89 * Find class implementing a specific operation interface.
90 *
91 * @param operationClass the interface which is requested.
92 * @return never returns null
93 * @throws FileSystemException if operationClass is not a known FileOperation interface.
94 */
95 protected final Class<? extends FileOperation> lookupOperation(final Class<? extends FileOperation> operationClass)
96 throws FileSystemException {
97 // check validity of passed class
98 if (!FileOperation.class.isAssignableFrom(operationClass)) {
99 throw new FileSystemException("vfs.operation/wrong-type.error", operationClass);
100 }
101
102 // find appropriate class
103 Class<? extends FileOperation> foundClass = null;
104 for (final Class<? extends FileOperation> operation : operations) {
105 if (operationClass.isAssignableFrom(operation)) {
106 foundClass = operation;
107 break;
108 }
109 }
110
111 if (foundClass == null) {
112 throw new FileSystemException("vfs.operation/not-found.error", operationClass);
113 }
114
115 return foundClass;
116 }
117
118 /**
119 * Add new FileOperation to list of known operations.
120 *
121 * @param operationClass a class implementing FileOperation.
122 * @throws FileSystemException if instances of the class cannot be assigned to FileOperation.
123 */
124 protected final void addOperation(final Class<? extends FileOperation> operationClass) throws FileSystemException {
125 // check validity of passed class
126 if (!FileOperation.class.isAssignableFrom(operationClass)) {
127 throw new FileSystemException("vfs.operation/cant-register.error", operationClass);
128 }
129
130 // ok, lets add it to the list
131 operations.add(operationClass);
132 }
133 }