org.springframework.core.io.ClassPathResource Maven / Gradle / Ivy
/*
* Copyright 2002-2023 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.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
/**
* {@link Resource} implementation for class path resources. Uses either a
* given {@link ClassLoader} or a given {@link Class} for loading resources.
*
* Supports resolution as {@code java.io.File} if the class path
* resource resides in the file system, but not for resources in a JAR.
* Always supports resolution as {@code java.net.URL}.
*
* @author Juergen Hoeller
* @author Sam Brannen
* @since 28.12.2003
* @see ClassLoader#getResourceAsStream(String)
* @see ClassLoader#getResource(String)
* @see Class#getResourceAsStream(String)
* @see Class#getResource(String)
*/
public class ClassPathResource extends AbstractFileResolvingResource {
/**
* Internal representation of the original path supplied by the user,
* used for creating relative paths and resolving URLs and InputStreams.
*/
private final String path;
private final String absolutePath;
@Nullable
private final ClassLoader classLoader;
@Nullable
private final Class clazz;
/**
* Create a new {@code ClassPathResource} for {@code ClassLoader} usage.
*
A leading slash will be removed, as the {@code ClassLoader} resource
* access methods will not accept it.
*
The default class loader will be used for loading the resource.
* @param path the absolute path within the class path
* @see ClassUtils#getDefaultClassLoader()
*/
public ClassPathResource(String path) {
this(path, (ClassLoader) null);
}
/**
* Create a new {@code ClassPathResource} for {@code ClassLoader} usage.
*
A leading slash will be removed, as the {@code ClassLoader} resource
* access methods will not accept it.
*
If the supplied {@code ClassLoader} is {@code null}, the default class
* loader will be used for loading the resource.
* @param path the absolute path within the class path
* @param classLoader the class loader to load the resource with
* @see ClassUtils#getDefaultClassLoader()
*/
public ClassPathResource(String path, @Nullable ClassLoader classLoader) {
Assert.notNull(path, "Path must not be null");
String pathToUse = StringUtils.cleanPath(path);
if (pathToUse.startsWith("/")) {
pathToUse = pathToUse.substring(1);
}
this.path = pathToUse;
this.absolutePath = pathToUse;
this.classLoader = (classLoader != null ? classLoader : ClassUtils.getDefaultClassLoader());
this.clazz = null;
}
/**
* Create a new {@code ClassPathResource} for {@code Class} usage.
*
The path can be relative to the given class, or absolute within
* the class path via a leading slash.
*
If the supplied {@code Class} is {@code null}, the default class
* loader will be used for loading the resource.
* @param path relative or absolute path within the class path
* @param clazz the class to load resources with
* @see ClassUtils#getDefaultClassLoader()
*/
public ClassPathResource(String path, @Nullable Class clazz) {
Assert.notNull(path, "Path must not be null");
this.path = StringUtils.cleanPath(path);
String absolutePath = this.path;
if (clazz != null && !absolutePath.startsWith("/")) {
absolutePath = ClassUtils.classPackageAsResourcePath(clazz) + "/" + absolutePath;
}
else if (absolutePath.startsWith("/")) {
absolutePath = absolutePath.substring(1);
}
this.absolutePath = absolutePath;
this.classLoader = null;
this.clazz = clazz;
}
/**
* Return the absolute path for this resource, as a
* {@linkplain StringUtils#cleanPath(String) cleaned} resource path within
* the class path.
*
The path returned by this method does not have a leading slash and is
* suitable for use with {@link ClassLoader#getResource(String)}.
*/
public final String getPath() {
return this.absolutePath;
}
/**
* Return the {@link ClassLoader} that this resource will be obtained from.
*/
@Nullable
public final ClassLoader getClassLoader() {
return (this.clazz != null ? this.clazz.getClassLoader() : this.classLoader);
}
/**
* This implementation checks for the resolution of a resource URL.
* @see ClassLoader#getResource(String)
* @see Class#getResource(String)
*/
@Override
public boolean exists() {
return (resolveURL() != null);
}
/**
* This implementation checks for the resolution of a resource URL upfront,
* then proceeding with {@link AbstractFileResolvingResource}'s length check.
* @see ClassLoader#getResource(String)
* @see Class#getResource(String)
*/
@Override
public boolean isReadable() {
URL url = resolveURL();
return (url != null && checkReadable(url));
}
/**
* Resolves a {@link URL} for the underlying class path resource.
* @return the resolved URL, or {@code null} if not resolvable
*/
@Nullable
protected URL resolveURL() {
try {
if (this.clazz != null) {
return this.clazz.getResource(this.path);
}
else if (this.classLoader != null) {
return this.classLoader.getResource(this.absolutePath);
}
else {
return ClassLoader.getSystemResource(this.absolutePath);
}
}
catch (IllegalArgumentException ex) {
// Should not happen according to the JDK's contract:
// see https://github.com/openjdk/jdk/pull/2662
return null;
}
}
/**
* This implementation opens an {@link InputStream} for the underlying class
* path resource, if available.
* @see ClassLoader#getResourceAsStream(String)
* @see Class#getResourceAsStream(String)
* @see ClassLoader#getSystemResourceAsStream(String)
*/
@Override
public InputStream getInputStream() throws IOException {
InputStream is;
if (this.clazz != null) {
is = this.clazz.getResourceAsStream(this.path);
}
else if (this.classLoader != null) {
is = this.classLoader.getResourceAsStream(this.absolutePath);
}
else {
is = ClassLoader.getSystemResourceAsStream(this.absolutePath);
}
if (is == null) {
throw new FileNotFoundException(getDescription() + " cannot be opened because it does not exist");
}
return is;
}
/**
* This implementation returns a URL for the underlying class path resource,
* if available.
* @see ClassLoader#getResource(String)
* @see Class#getResource(String)
*/
@Override
public URL getURL() throws IOException {
URL url = resolveURL();
if (url == null) {
throw new FileNotFoundException(getDescription() + " cannot be resolved to URL because it does not exist");
}
return url;
}
/**
* This implementation creates a {@code ClassPathResource}, applying the given
* path relative to the path used to create this descriptor.
* @see StringUtils#applyRelativePath(String, String)
*/
@Override
public Resource createRelative(String relativePath) {
String pathToUse = StringUtils.applyRelativePath(this.path, relativePath);
return (this.clazz != null ? new ClassPathResource(pathToUse, this.clazz) :
new ClassPathResource(pathToUse, this.classLoader));
}
/**
* This implementation returns the name of the file that this class path
* resource refers to.
* @see StringUtils#getFilename(String)
*/
@Override
@Nullable
public String getFilename() {
return StringUtils.getFilename(this.absolutePath);
}
/**
* This implementation returns a description that includes the absolute
* class path location.
*/
@Override
public String getDescription() {
return "class path resource [" + this.absolutePath + ']';
}
/**
* This implementation compares the underlying class path locations and
* associated class loaders.
* @see #getPath()
* @see #getClassLoader()
*/
@Override
public boolean equals(@Nullable Object obj) {
if (this == obj) {
return true;
}
return ((obj instanceof ClassPathResource that) &&
this.absolutePath.equals(that.absolutePath) &&
ObjectUtils.nullSafeEquals(getClassLoader(), that.getClassLoader()));
}
/**
* This implementation returns the hash code of the underlying class path location.
* @see #getPath()
*/
@Override
public int hashCode() {
return this.absolutePath.hashCode();
}
}