LocalVariableTableParameterNameDiscoverer.java

/*
 * Copyright 2002-2014 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.core;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

import org.jephyr.parameters.ParameterNamesCache;
import org.springframework.asm.Type;

/**
 * Implementation of {@link ParameterNameDiscoverer} that uses the LocalVariableTable
 * information in the method attributes to discover parameter names. Returns
 * {@code null} if the class file was compiled without debug information.
 *
 * <p>Uses ObjectWeb's ASM library for analyzing class files. Each discoverer instance
 * caches the ASM discovered information for each introspected Class, in a thread-safe
 * manner. It is recommended to reuse ParameterNameDiscoverer instances as far as possible.
 *
 * @author Adrian Colyer
 * @author Costin Leau
 * @author Juergen Hoeller
 * @author Chris Beams
 * @since 2.0
 */
public class LocalVariableTableParameterNameDiscoverer implements ParameterNameDiscoverer {

	@Override
	public String[] getParameterNames(Method method) {
		Class<?> cls = method.getDeclaringClass();
		return ParameterNamesCache.getParameterNames(cls.getClassLoader(), Type.getInternalName(cls), method.getName(),
				Type.getMethodDescriptor(method));
	}

	@Override
	public String[] getParameterNames(Constructor<?> ctor) {
		Class<?> cls = ctor.getDeclaringClass();
		return ParameterNamesCache.getParameterNames(cls.getClassLoader(), Type.getInternalName(cls), "<init>",
				Type.getConstructorDescriptor(ctor));
	}
}