1 /*
2 * Copyright 2002-2006 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.springframework.core.io;
18
19 import java.io.IOException;
20 import java.io.InputStream;
21
22 /**
23 * {@link Resource} implementation for a given InputStream. Should only
24 * be used if no specific Resource implementation is applicable.
25 * In particular, prefer {@link ByteArrayResource} or any of the
26 * file-based Resource implementations where possible.
27 *
28 * <p>In contrast to other Resource implementations, this is a descriptor
29 * for an <i>already opened</i> resource - therefore returning "true" from
30 * <code>isOpen()</code>. Do not use it if you need to keep the resource
31 * descriptor somewhere, or if you need to read a stream multiple times.
32 *
33 * @author Juergen Hoeller
34 * @since 28.12.2003
35 * @see ByteArrayResource
36 * @see ClassPathResource
37 * @see FileSystemResource
38 * @see UrlResource
39 */
40 public class InputStreamResource extends AbstractResource {
41
42 private final InputStream inputStream;
43
44 private final String description;
45
46 private boolean read = false;
47
48
49 /**
50 * Create a new InputStreamResource.
51 * @param inputStream the InputStream to use
52 */
53 public InputStreamResource(InputStream inputStream) {
54 this(inputStream, "resource loaded through InputStream");
55 }
56
57 /**
58 * Create a new InputStreamResource.
59 * @param inputStream the InputStream to use
60 * @param description where the InputStream comes from
61 */
62 public InputStreamResource(InputStream inputStream, String description) {
63 if (inputStream == null) {
64 throw new IllegalArgumentException("InputStream must not be null");
65 }
66 this.inputStream = inputStream;
67 this.description = (description != null ? description : "");
68 }
69
70
71 /**
72 * This implementation always returns <code>true</code>.
73 */
74 public boolean exists() {
75 return true;
76 }
77
78 /**
79 * This implementation always returns <code>true</code>.
80 */
81 public boolean isOpen() {
82 return true;
83 }
84
85 /**
86 * This implementation throws IllegalStateException if attempting to
87 * read the underlying stream multiple times.
88 */
89 public InputStream getInputStream() throws IOException, IllegalStateException {
90 if (this.read) {
91 throw new IllegalStateException("InputStream has already been read - " +
92 "do not use InputStreamResource if a stream needs to be read multiple times");
93 }
94 this.read = true;
95 return this.inputStream;
96 }
97
98 /**
99 * This implementation returns the passed-in description, if any.
100 */
101 public String getDescription() {
102 return this.description;
103 }
104
105
106 /**
107 * This implementation compares the underlying InputStream.
108 */
109 public boolean equals(Object obj) {
110 return (obj == this ||
111 (obj instanceof InputStreamResource && ((InputStreamResource) obj).inputStream.equals(this.inputStream)));
112 }
113
114 /**
115 * This implementation returns the hash code of the underlying InputStream.
116 */
117 public int hashCode() {
118 return this.inputStream.hashCode();
119 }
120
121 }
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