001/* 002 * Copyright 2002-2017 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.core.io; 018 019import java.io.IOException; 020import java.io.InputStream; 021 022/** 023 * Simple interface for objects that are sources for an {@link InputStream}. 024 * 025 * <p>This is the base interface for Spring's more extensive {@link Resource} interface. 026 * 027 * <p>For single-use streams, {@link InputStreamResource} can be used for any 028 * given {@code InputStream}. Spring's {@link ByteArrayResource} or any 029 * file-based {@code Resource} implementation can be used as a concrete 030 * instance, allowing one to read the underlying content stream multiple times. 031 * This makes this interface useful as an abstract content source for mail 032 * attachments, for example. 033 * 034 * @author Juergen Hoeller 035 * @since 20.01.2004 036 * @see java.io.InputStream 037 * @see Resource 038 * @see InputStreamResource 039 * @see ByteArrayResource 040 */ 041public interface InputStreamSource { 042 043 /** 044 * Return an {@link InputStream} for the content of an underlying resource. 045 * <p>It is expected that each call creates a <i>fresh</i> stream. 046 * <p>This requirement is particularly important when you consider an API such 047 * as JavaMail, which needs to be able to read the stream multiple times when 048 * creating mail attachments. For such a use case, it is <i>required</i> 049 * that each {@code getInputStream()} call returns a fresh stream. 050 * @return the input stream for the underlying resource (must not be {@code null}) 051 * @throws java.io.FileNotFoundException if the underlying resource doesn't exist 052 * @throws IOException if the content stream could not be opened 053 */ 054 InputStream getInputStream() throws IOException; 055 056}