ClassPathUtils.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.lang3;
import java.util.Objects;
/**
* Operations regarding the classpath.
*
* <p>
* The methods of this class do not allow {@code null} inputs.
* </p>
*
* @since 3.3
*/
//@Immutable
public class ClassPathUtils {
/**
* Gets the package name of the context class.
* <p>
* Returns an empty string for an unnamed package, including when {@link Class#getPackage()} returns {@code null} on Java 8.
* </p>
*
* @param context The context class, must not be {@code null}.
* @return The package name, or an empty string for an unnamed package.
* @throws NullPointerException Thrown if {@code context} is null, represents an array, a primitive type or {@code void}, or represents a named class whose
* package is unavailable.
*/
private static String getPackageName(final Class<?> context) {
final Package contextPackage = context.getPackage();
if (contextPackage == null && !context.isArray() && !context.isPrimitive() && context.getName().indexOf('.') < 0) {
return StringUtils.EMPTY;
}
return Objects.requireNonNull(contextPackage, "context").getName();
}
/**
* Converts a package name to a Java path ('/').
*
* @param path The source path.
* @return A package name.
* @throws NullPointerException Thrown if {@code path} is null.
* @since 3.13.0
*/
public static String packageToPath(final String path) {
return Objects.requireNonNull(path, "path").replace('.', '/');
}
/**
* Converts a Java path ('/') to a package name.
*
* @param path The source path.
* @return A package name.
* @throws NullPointerException Thrown if {@code path} is null.
* @since 3.13.0
*/
public static String pathToPackage(final String path) {
return Objects.requireNonNull(path, "path").replace('/', '.');
}
/**
* Qualifies a resource name with a prefix and separator.
* <p>
* Returns {@code resourceName} unchanged when the prefix is empty.
* </p>
*
* @param prefix The package name or path, must not be {@code null}.
* @param resourceName The resource name, validated as non-null by the caller.
* @param separator The separator between the prefix and resource name.
* @return The qualified resource name, or the unchanged resource name when the prefix is empty.
* @throws NullPointerException Thrown if {@code prefix} is null.
*/
private static String qualify(final String prefix, final String resourceName, final char separator) {
return prefix.isEmpty() ? resourceName : prefix + separator + resourceName;
}
/**
* Returns the fully qualified name for the resource with name {@code resourceName} relative to the given context.
*
* <p>
* Note that this method does not check whether the resource actually exists. It only constructs the name. Null inputs are not allowed.
* </p>
*
* <p>
* If the context class is in an unnamed package, returns {@code resourceName} unchanged.
* </p>
*
* <pre>
* ClassPathUtils.toFullyQualifiedName(StringUtils.class, "StringUtils.properties") = "org.apache.commons.lang3.StringUtils.properties"
* </pre>
*
* @param context The context for constructing the name.
* @param resourceName The resource name to construct the fully qualified name for.
* @return The fully qualified name of the resource with name {@code resourceName}.
* @throws NullPointerException Thrown if either {@code context} or {@code resourceName} is null, if {@code context} represents an array, a primitive
* type or {@code void}, or if it represents a named class whose package is unavailable.
*/
public static String toFullyQualifiedName(final Class<?> context, final String resourceName) {
Objects.requireNonNull(context, "context");
Objects.requireNonNull(resourceName, "resourceName");
return qualify(getPackageName(context), resourceName, '.');
}
/**
* Returns the fully qualified name for the resource with name {@code resourceName} relative to the given context.
*
* <p>
* Note that this method does not check whether the resource actually exists. It only constructs the name. Null inputs are not allowed.
* </p>
*
* <p>
* If the context is an unnamed package, returns {@code resourceName} unchanged.
* </p>
*
* <pre>
* ClassPathUtils.toFullyQualifiedName(StringUtils.class.getPackage(), "StringUtils.properties") = "org.apache.commons.lang3.StringUtils.properties"
* </pre>
*
* @param context The context for constructing the name.
* @param resourceName The resource name to construct the fully qualified name for.
* @return The fully qualified name of the resource with name {@code resourceName}.
* @throws NullPointerException Thrown if either {@code context} or {@code resourceName} is null.
*/
public static String toFullyQualifiedName(final Package context, final String resourceName) {
Objects.requireNonNull(context, "context");
Objects.requireNonNull(resourceName, "resourceName");
return qualify(context.getName(), resourceName, '.');
}
/**
* Returns the fully qualified path for the resource with name {@code resourceName} relative to the given context.
*
* <p>
* Note that this method does not check whether the resource actually exists. It only constructs the path. Null inputs are not allowed.
* </p>
*
* <p>
* If the context class is in an unnamed package, returns {@code resourceName} unchanged.
* </p>
*
* <pre>
* ClassPathUtils.toFullyQualifiedPath(StringUtils.class, "StringUtils.properties") = "org/apache/commons/lang3/StringUtils.properties"
* </pre>
*
* @param context The context for constructing the path.
* @param resourceName The resource name to construct the fully qualified path for.
* @return The fully qualified path of the resource with name {@code resourceName}.
* @throws NullPointerException Thrown if either {@code context} or {@code resourceName} is null, if {@code context} represents an array, a primitive
* type or {@code void}, or if it represents a named class whose package is unavailable.
*/
public static String toFullyQualifiedPath(final Class<?> context, final String resourceName) {
Objects.requireNonNull(context, "context");
Objects.requireNonNull(resourceName, "resourceName");
return qualify(packageToPath(getPackageName(context)), resourceName, '/');
}
/**
* Returns the fully qualified path for the resource with name {@code resourceName} relative to the given context.
*
* <p>
* Note that this method does not check whether the resource actually exists. It only constructs the path. Null inputs are not allowed.
* </p>
*
* <p>
* If the context is an unnamed package, returns {@code resourceName} unchanged.
* </p>
*
* <pre>
* ClassPathUtils.toFullyQualifiedPath(StringUtils.class.getPackage(), "StringUtils.properties") = "org/apache/commons/lang3/StringUtils.properties"
* </pre>
*
* @param context The context for constructing the path.
* @param resourceName The resource name to construct the fully qualified path for.
* @return The fully qualified path of the resource with name {@code resourceName}.
* @throws NullPointerException Thrown if either {@code context} or {@code resourceName} is null.
*/
public static String toFullyQualifiedPath(final Package context, final String resourceName) {
Objects.requireNonNull(context, "context");
Objects.requireNonNull(resourceName, "resourceName");
return qualify(packageToPath(context.getName()), resourceName, '/');
}
/**
* {@link ClassPathUtils} instances should NOT be constructed in standard programming. Instead, the class should be used as
* {@code ClassPathUtils.toFullyQualifiedName(MyClass.class, "MyClass.properties");}.
*
* <p>
* This constructor is public to permit tools that require a JavaBean instance to operate.
* </p>
*
* @deprecated TODO Make private in 4.0.
*/
@Deprecated
public ClassPathUtils() {
// empty
}
}