/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core.io;

import java.io.IOException;
import java.io.InputStream;

Simple interface for objects that are sources for an InputStream. 
This is the base interface for Spring's more extensive Resource interface. 
For single-use streams, InputStreamResource can be used for any given InputStream. Spring's ByteArrayResource or any file-based Resource implementation can be used as a concrete instance, allowing one to read the underlying content stream multiple times. This makes this interface useful as an abstract content source for mail attachments, for example. 
Author:
Juergen Hoeller
See Also:
InputStream
Resource
InputStreamResource
ByteArrayResource
Since:
20.01.2004/**
 * Simple interface for objects that are sources for an {@link InputStream}.
 *
 * <p>This is the base interface for Spring's more extensive {@link Resource} interface.
 *
 * <p>For single-use streams, {@link InputStreamResource} can be used for any
 * given {@code InputStream}. Spring's {@link ByteArrayResource} or any
 * file-based {@code Resource} implementation can be used as a concrete
 * instance, allowing one to read the underlying content stream multiple times.
 * This makes this interface useful as an abstract content source for mail
 * attachments, for example.
 *
 * @author Juergen Hoeller
 * @since 20.01.2004
 * @see java.io.InputStream
 * @see Resource
 * @see InputStreamResource
 * @see ByteArrayResource
 */
public interface InputStreamSource {

	
Return an InputStream for the content of an underlying resource. 
It is expected that each call creates a fresh stream.
This requirement is particularly important when you consider an API such
as JavaMail, which needs to be able to read the stream multiple times when
creating mail attachments. For such a use case, it is required that each getInputStream() call returns a fresh stream. 
Throws:
FileNotFoundException – if the underlying resource doesn't exist
IOException – if the content stream could not be opened
Returns:
the input stream for the underlying resource (must not be null)/**
	 * Return an {@link InputStream} for the content of an underlying resource.
	 * <p>It is expected that each call creates a <i>fresh</i> stream.
	 * <p>This requirement is particularly important when you consider an API such
	 * as JavaMail, which needs to be able to read the stream multiple times when
	 * creating mail attachments. For such a use case, it is <i>required</i>
	 * that each {@code getInputStream()} call returns a fresh stream.
	 * @return the input stream for the underlying resource (must not be {@code null})
	 * @throws java.io.FileNotFoundException if the underlying resource doesn't exist
	 * @throws IOException if the content stream could not be opened
	 */
	InputStream getInputStream() throws IOException;

}