1 /*
2 * Copyright 2002-2012 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 * Simple interface for objects that are sources for an {@link InputStream}.
24 *
25 * <p>This is the base interface for Spring's more extensive {@link Resource} interface.
26 *
27 * <p>For single-use streams, {@link InputStreamResource} can be used for any
28 * given <code>InputStream</code>. Spring's {@link ByteArrayResource} or any
29 * file-based <code>Resource</code> implementation can be used as a concrete
30 * instance, allowing one to read the underlying content stream multiple times.
31 * This makes this interface useful as an abstract content source for mail
32 * attachments, for example.
33 *
34 * @author Juergen Hoeller
35 * @since 20.01.2004
36 * @see java.io.InputStream
37 * @see Resource
38 * @see InputStreamResource
39 * @see ByteArrayResource
40 */
41 public interface InputStreamSource {
42
43 /**
44 * Return an {@link InputStream}.
45 * <p>It is expected that each call creates a <i>fresh</i> stream.
46 * <p>This requirement is particularly important when you consider an API such
47 * as JavaMail, which needs to be able to read the stream multiple times when
48 * creating mail attachments. For such a use case, it is <i>required</i>
49 * that each <code>getInputStream()</code> call returns a fresh stream.
50 * @return the input stream for the underlying resource (must not be {@code null})
51 * @throws IOException if the stream could not be opened
52 * @see org.springframework.mail.javamail.MimeMessageHelper#addAttachment(String, InputStreamSource)
53 */
54 InputStream getInputStream() throws IOException;
55
56 }