org.springframework.core.io.FileUrlResource Maven / Gradle / Ivy
/*
* Copyright 2002-2020 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.File;
import java.io.IOException;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.channels.FileChannel;
import java.nio.channels.WritableByteChannel;
import java.nio.file.Files;
import java.nio.file.StandardOpenOption;
import org.springframework.lang.Nullable;
import org.springframework.util.ResourceUtils;
/**
* Subclass of {@link UrlResource} which assumes file resolution, to the degree
* of implementing the {@link WritableResource} interface for it. This resource
* variant also caches resolved {@link File} handles from {@link #getFile()}.
*
* This is the class resolved by {@link DefaultResourceLoader} for a "file:..."
* URL location, allowing a downcast to {@link WritableResource} for it.
*
*
Alternatively, for direct construction from a {@link java.io.File} handle
* or NIO {@link java.nio.file.Path}, consider using {@link FileSystemResource}.
*
* @author Juergen Hoeller
* @since 5.0.2
*/
public class FileUrlResource extends UrlResource implements WritableResource {
@Nullable
private volatile File file;
/**
* Create a new {@code FileUrlResource} based on the given URL object.
*
Note that this does not enforce "file" as URL protocol. If a protocol
* is known to be resolvable to a file, it is acceptable for this purpose.
* @param url a URL
* @see ResourceUtils#isFileURL(URL)
* @see #getFile()
*/
public FileUrlResource(URL url) {
super(url);
}
/**
* Create a new {@code FileUrlResource} based on the given file location,
* using the URL protocol "file".
*
The given parts will automatically get encoded if necessary.
* @param location the location (i.e. the file path within that protocol)
* @throws MalformedURLException if the given URL specification is not valid
* @see UrlResource#UrlResource(String, String)
* @see ResourceUtils#URL_PROTOCOL_FILE
*/
public FileUrlResource(String location) throws MalformedURLException {
super(ResourceUtils.URL_PROTOCOL_FILE, location);
}
@Override
public File getFile() throws IOException {
File file = this.file;
if (file != null) {
return file;
}
file = super.getFile();
this.file = file;
return file;
}
@Override
public boolean isWritable() {
try {
File file = getFile();
return (file.canWrite() && !file.isDirectory());
}
catch (IOException ex) {
return false;
}
}
@Override
public OutputStream getOutputStream() throws IOException {
return Files.newOutputStream(getFile().toPath());
}
@Override
public WritableByteChannel writableChannel() throws IOException {
return FileChannel.open(getFile().toPath(), StandardOpenOption.WRITE);
}
@Override
public Resource createRelative(String relativePath) throws MalformedURLException {
return new FileUrlResource(createRelativeURL(relativePath));
}
}