org.springframework.core.io.InputStreamResource Maven / Gradle / Ivy
/*
* Copyright 2002-2024 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;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* {@link Resource} implementation for a given {@link InputStream} or a given
* {@link InputStreamSource} (which can be supplied as a lambda expression)
* for a lazy {@link InputStream} on demand.
*
* 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 if possible. If you need to obtain
* a custom stream multiple times, use a custom {@link AbstractResource} subclass
* with a corresponding {@code getInputStream()} implementation.
*
*
In contrast to other {@code Resource} implementations, this is a descriptor
* for an already opened resource - therefore returning {@code true} from
* {@link #isOpen()}. 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. This also applies when constructed with an {@code InputStreamSource}
* which lazily obtains the stream but only allows for single access as well.
*
* @author Juergen Hoeller
* @author Sam Brannen
* @since 28.12.2003
* @see ByteArrayResource
* @see ClassPathResource
* @see FileSystemResource
* @see UrlResource
*/
public class InputStreamResource extends AbstractResource {
private final InputStreamSource inputStreamSource;
private final String description;
private final Object equality;
private boolean read = false;
/**
* Create a new {@code InputStreamResource} with a lazy {@code InputStream}
* for single use.
* @param inputStreamSource an on-demand source for a single-use InputStream
* @since 6.1.7
*/
public InputStreamResource(InputStreamSource inputStreamSource) {
this(inputStreamSource, "resource loaded from InputStreamSource");
}
/**
* Create a new {@code InputStreamResource} with a lazy {@code InputStream}
* for single use.
* @param inputStreamSource an on-demand source for a single-use InputStream
* @param description where the InputStream comes from
* @since 6.1.7
*/
public InputStreamResource(InputStreamSource inputStreamSource, @Nullable String description) {
Assert.notNull(inputStreamSource, "InputStreamSource must not be null");
this.inputStreamSource = inputStreamSource;
this.description = (description != null ? description : "");
this.equality = inputStreamSource;
}
/**
* Create a new {@code InputStreamResource} for an existing {@code InputStream}.
*
Consider retrieving the InputStream on demand if possible, reducing its
* lifetime and reliably opening it and closing it through regular
* {@link InputStreamSource#getInputStream()} usage.
* @param inputStream the InputStream to use
* @see #InputStreamResource(InputStreamSource)
*/
public InputStreamResource(InputStream inputStream) {
this(inputStream, "resource loaded through InputStream");
}
/**
* Create a new {@code InputStreamResource} for an existing {@code InputStream}.
* @param inputStream the InputStream to use
* @param description where the InputStream comes from
* @see #InputStreamResource(InputStreamSource, String)
*/
public InputStreamResource(InputStream inputStream, @Nullable String description) {
Assert.notNull(inputStream, "InputStream must not be null");
this.inputStreamSource = () -> inputStream;
this.description = (description != null ? description : "");
this.equality = inputStream;
}
/**
* 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 {
if (this.read) {
throw new IllegalStateException("InputStream has already been read - " +
"do not use InputStreamResource if a stream needs to be read multiple times");
}
this.read = true;
return this.inputStreamSource.getInputStream();
}
/**
* This implementation returns a description that includes the passed-in
* description, if any.
*/
@Override
public String getDescription() {
return "InputStream resource [" + this.description + "]";
}
/**
* This implementation compares the underlying InputStream.
*/
@Override
public boolean equals(@Nullable Object other) {
return (this == other || (other instanceof InputStreamResource that &&
this.equality.equals(that.equality)));
}
/**
* This implementation returns the hash code of the underlying InputStream.
*/
@Override
public int hashCode() {
return this.equality.hashCode();
}
}