org.springframework.util.ResourceUtils Maven / Gradle / Ivy
/*
* Copyright 2002-2005 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
*
* http://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.util;
import java.io.File;
import java.io.FileNotFoundException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLDecoder;
/**
* Utility methods for resolving resource locations to files in the
* file system. Mainly for internal use within the framework.
*
* Consider using Spring's Resource abstraction in the core package
* for handling all kinds of file resources in a uniform manner.
* ResourceLoader's getLocation can resolve any location to a
* Resource object, which in turn allows to get a java.io.File
* in the file system through its getFile method.
*
*
The main reason for these utility methods for resource location
* handling is to support Log4jConfigurer, which must be able to resolve
* resource locations before the logging system has been initialized.
* Spring' Resource abstraction in the core package, on the other hand,
* already expects the logging system to be available.
*
* @author Juergen Hoeller
* @since 1.1.5
* @see org.springframework.core.io.Resource
* @see org.springframework.core.io.ClassPathResource
* @see org.springframework.core.io.FileSystemResource
* @see org.springframework.core.io.UrlResource
* @see org.springframework.core.io.ResourceLoader
*/
public abstract class ResourceUtils {
/** Pseudo URL prefix for loading from the class path: "classpath:" */
public static final String CLASSPATH_URL_PREFIX = "classpath:";
/** URL prefix for loading from the file system: "file:" */
public static final String FILE_URL_PREFIX = "file:";
/** URL protocol for a file in the file system: "file" */
public static final String URL_PROTOCOL_FILE = "file";
/**
* Return whether the given resource location is a URL:
* either a special "classpath" pseudo URL or a standard URL.
* @see #CLASSPATH_URL_PREFIX
* @see java.net.URL
*/
public static boolean isUrl(String resourceLocation) {
if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) {
return true;
}
try {
new URL(resourceLocation);
return true;
}
catch (MalformedURLException ex) {
return false;
}
}
/**
* Resolve the given resource location to a java.net.URL.
*
Does not check whether the URL actually exists; simply returns
* the URL that the given location would correspond to.
* @param resourceLocation the resource location to resolve: either a
* "classpath:" pseudo URL, a "file:" URL, or a plain file path
* @return a corresponding URL object
* @throws FileNotFoundException if the resource cannot be resolved to a URL
*/
public static URL getURL(String resourceLocation) throws FileNotFoundException {
if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) {
String path = resourceLocation.substring(CLASSPATH_URL_PREFIX.length());
URL url = ClassUtils.getDefaultClassLoader().getResource(path);
if (url == null) {
String description = "class path resource [" + path + "]";
throw new FileNotFoundException(
description + " cannot be resolved to URL because it does not exist");
}
return url;
}
try {
// try URL
return new URL(resourceLocation);
}
catch (MalformedURLException ex) {
// no URL -> treat as file path
try {
return new URL(FILE_URL_PREFIX + resourceLocation);
}
catch (MalformedURLException ex2) {
throw new FileNotFoundException("Resource location [" + resourceLocation +
"] is neither a URL not a well-formed file path");
}
}
}
/**
* Resolve the given resource location to a java.io.File,
* i.e. to a file in the file system.
*
Does not check whether the fil actually exists; simply returns
* the File that the given location would correspond to.
* @param resourceLocation the resource location to resolve: either a
* "classpath:" pseudo URL, a "file:" URL, or a plain file path
* @return a corresponding File object
* @throws FileNotFoundException if the resource cannot be resolved to
* a file in the file system
*/
public static File getFile(String resourceLocation) throws FileNotFoundException {
if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) {
String path = resourceLocation.substring(CLASSPATH_URL_PREFIX.length());
String description = "class path resource [" + path + "]";
URL url = ClassUtils.getDefaultClassLoader().getResource(path);
if (url == null) {
throw new FileNotFoundException(
description + " cannot be resolved to absolute file path " +
"because it does not reside in the file system");
}
return getFile(url, description);
}
try {
// try URL
return getFile(new URL(resourceLocation));
}
catch (MalformedURLException ex) {
// no URL -> treat as file path
return new File(resourceLocation);
}
}
/**
* Resolve the given resource URL to a java.io.File,
* i.e. to a file in the file system.
* @param resourceUrl the resource URL to resolve
* @return a corresponding File object
* @throws FileNotFoundException if the URL cannot be resolved to
* a file in the file system
*/
public static File getFile(URL resourceUrl) throws FileNotFoundException {
return getFile(resourceUrl, "URL");
}
/**
* Resolve the given resource URL to a java.io.File,
* i.e. to a file in the file system.
* @param resourceUrl the resource URL to resolve
* @param description a description of the original resource that
* the URL was created for (for example, a class path location)
* @return a corresponding File object
* @throws FileNotFoundException if the URL cannot be resolved to
* a file in the file system
*/
public static File getFile(URL resourceUrl, String description) throws FileNotFoundException {
if (!URL_PROTOCOL_FILE.equals(resourceUrl.getProtocol())) {
throw new FileNotFoundException(
description + " cannot be resolved to absolute file path " +
"because it does not reside in the file system: " + resourceUrl);
}
return new File(URLDecoder.decode(resourceUrl.getFile()));
}
}