cn.taketoday.core.io.InputStreamResource Maven / Gradle / Ivy
/*
* Original Author -> Harry Yang ([email protected]) https://taketoday.cn
* Copyright © TODAY & 2017 - 2021 All Rights Reserved.
*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see [http://www.gnu.org/licenses/]
*/
package cn.taketoday.core.io;
import java.io.IOException;
import java.io.InputStream;
import cn.taketoday.lang.Assert;
/**
* {@link Resource} implementation for a given {@link InputStream}.
* Should only be used if no other specific {@code Resource} implementation
* is applicable. In particular, prefer {@link ByteArrayResource} or any of the
* file-based {@code Resource} implementations where possible.
*
*
In contrast to other {@code Resource} implementations, this is a descriptor
* for an already opened resource. Do not use an {@code InputStreamResource}
* if you need to keep the resource descriptor somewhere, or if you need to read
* from a stream multiple times.
*
* @author Juergen Hoeller
* @author Sam Brannen
* @author TODAY 2021/3/7 11:18
* @see ByteArrayResource
* @see ClassPathResource
* @see FileSystemResource
* @see UrlResource
* @since 3.0
*/
public class InputStreamResource extends AbstractResource {
private boolean read = false;
private final String description;
private final InputStream inputStream;
/**
* Create a new InputStreamResource.
*
* @param inputStream the InputStream to use
*/
public InputStreamResource(InputStream inputStream) {
this(inputStream, "resource loaded through InputStream");
}
/**
* Create a new InputStreamResource.
*
* @param inputStream the InputStream to use
* @param description where the InputStream comes from
*/
public InputStreamResource(InputStream inputStream, String description) {
Assert.notNull(inputStream, "InputStream must not be null");
this.inputStream = inputStream;
this.description = (description != null ? description : "");
}
/**
* This implementation always returns {@code true}.
*/
@Override
public boolean exists() {
return true;
}
/**
* This implementation always returns {@code true}.
*/
@Override
public boolean isOpen() {
return true;
}
/**
* This implementation throws IllegalStateException if attempting to
* read the underlying stream multiple times.
*/
@Override
public InputStream getInputStream() throws IOException, IllegalStateException {
Assert.state(!read, "InputStream has already been read - do not use InputStreamResource if a stream needs to be read multiple times");
this.read = true;
return this.inputStream;
}
/**
* This implementation returns a description that includes the passed-in
* description, if any.
*/
@Override
public String toString() {
return "InputStream resource [" + this.description + "]";
}
/**
* This implementation compares the underlying InputStream.
*/
@Override
public boolean equals(Object other) {
return (this == other || (other instanceof InputStreamResource &&
((InputStreamResource) other).inputStream.equals(this.inputStream)));
}
/**
* This implementation returns the hash code of the underlying InputStream.
*/
@Override
public int hashCode() {
return this.inputStream.hashCode();
}
}