ReflectionUtil.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
 * 
 *      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.apache.el.util;

import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.util.Arrays;

import javax.el.ELException;
import javax.el.MethodNotFoundException;
import javax.el.PropertyNotFoundException;

import org.apache.el.lang.ELSupport;


/**
 * Utilities for Managing Serialization and Reflection
 * 
 * @author Jacob Hookom [jacob@hookom.net]
 *
 */
public class ReflectionUtil {

    protected static final String[] EMPTY_STRING = new String[0];

    protected static final String[] PRIMITIVE_NAMES = new String[] { "boolean",
            "byte", "char", "double", "float", "int", "long", "short", "void" };

    protected static final Class[] PRIMITIVES = new Class[] { boolean.class,
            byte.class, char.class, double.class, float.class, int.class,
            long.class, short.class, Void.TYPE };

    /**
     * 
     */
    private ReflectionUtil() {
        super();
    }

    public static Class forName(String name) throws ClassNotFoundException {
        if (null == name || "".equals(name)) {
            return null;
        }
        Class c = forNamePrimitive(name);
        if (c == null) {
            if (name.endsWith("[]")) {
                String nc = name.substring(0, name.length() - 2);
                c = Class.forName(nc, true, Thread.currentThread().getContextClassLoader());
                c = Array.newInstance(c, 0).getClass();
            } else {
                c = Class.forName(name, true, Thread.currentThread().getContextClassLoader());
            }
        }
        return c;
    }

    protected static Class forNamePrimitive(String name) {
        if (name.length() <= 8) {
            int p = Arrays.binarySearch(PRIMITIVE_NAMES, name);
            if (p >= 0) {
                return PRIMITIVES[p];
            }
        }
        return null;
    }

    /**
     * Converts an array of Class names to Class types
     */
    public static Class[] toTypeArray(String[] s) throws ClassNotFoundException {
        if (s == null)
            return null;
        Class[] c = new Class[s.length];
        for (int i = 0; i < s.length; i++) {
            c[i] = forName(s[i]);
        }
        return c;
    }

    /**
     * Converts an array of Class types to Class names
     */
    public static String[] toTypeNameArray(Class[] c) {
        if (c == null)
            return null;
        String[] s = new String[c.length];
        for (int i = 0; i < c.length; i++) {
            s[i] = c[i].getName();
        }
        return s;
    }

    /**
     * Returns a method based on the criteria
     * @param base the object that owns the method
     * @param property the name of the method
     * @param paramTypes the parameter types to use
     * @return the method specified
     * @throws MethodNotFoundException
     */
    public static Method getMethod(Object base, Object property,
            Class[] paramTypes) throws MethodNotFoundException {
        if (base == null || property == null) {
            throw new MethodNotFoundException(MessageFactory.get(
                    "error.method.notfound", base, property,
                    paramString(paramTypes)));
        }

        String methodName = (property instanceof String) ? (String) property
                : property.toString();

        Method method = null;
        try {
            method = base.getClass().getMethod(methodName, paramTypes);
        } catch (NoSuchMethodException nsme) {
            throw new MethodNotFoundException(MessageFactory.get(
                    "error.method.notfound", base, property,
                    paramString(paramTypes)));
        }
        return method;
    }

    protected static final String paramString(Class[] types) {
        if (types != null) {
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < types.length; i++) {
                sb.append(types[i].getName()).append(", ");
            }
            if (sb.length() > 2) {
                sb.setLength(sb.length() - 2);
            }
            return sb.toString();
        }
        return null;
    }


    public static PropertyDescriptor getPropertyDescriptor(Object base,
            Object property) throws ELException, PropertyNotFoundException {
        String name = ELSupport.coerceToString(property);
        PropertyDescriptor p = null;
        try {
            PropertyDescriptor[] desc = Introspector.getBeanInfo(
                    base.getClass()).getPropertyDescriptors();
            for (int i = 0; i < desc.length; i++) {
                if (desc[i].getName().equals(name)) {
                    return desc[i];
                }
            }
        } catch (IntrospectionException ie) {
            throw new ELException(ie);
        }
        throw new PropertyNotFoundException(MessageFactory.get(
                "error.property.notfound", base, name));
    }
}