dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/CompatibleTypeUtils.java

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * 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 com.alibaba.dubbo.common.utils;

import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * @author ding.lid
 */
public class CompatibleTypeUtils {
    
    private CompatibleTypeUtils() {
    }

    private static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";

    /**
     * 兼容类型转换。null值是OK的。如果不需要转换，则返回原来的值。
     * 进行的兼容类型转换如下：（基本类对应的Wrapper类型不再列出。）
     * <ul>
     * <li> String -> char, enum, Date
     * <li> byte, short, int, long -> byte, short, int, long
     * <li> float, double -> float, double
     * </ul>
     */
    @SuppressWarnings({ "unchecked", "rawtypes" })
	public static Object compatibleTypeConvert(Object value, Class<?> type) {
        if(value == null || type == null || type.isAssignableFrom(value.getClass())) {
        	return value;
        }
        if(value instanceof String) {
            String string = (String) value;
            if (char.class.equals(type) || Character.class.equals(type)) {
                if(string.length() != 1) {
                    throw new IllegalArgumentException(String.format("CAN NOT convert String(%s) to char!" +
                            " when convert String to char, the String MUST only 1 char.", string));
                }
                return string.charAt(0);
            } else if(type.isEnum()) {
                return Enum.valueOf((Class<Enum>)type, string);
            } else if(type == BigInteger.class) {
                return new BigInteger(string);
            } else if(type == BigDecimal.class) {
                return new BigDecimal(string);
            } else if(type == Date.class) {
                try {
                    return new SimpleDateFormat(DATE_FORMAT).parse((String) value);
                } catch (ParseException e) {
                    throw new IllegalStateException("Failed to parse date " + value + " by format " + DATE_FORMAT + ", cause: " + e.getMessage(), e);
                }
            }
        } else if(value instanceof Number) {
            Number number = (Number) value;
            if (type == byte.class || type == Byte.class) {
                return number.byteValue();
            } else if (type == short.class || type == Short.class) {
                return number.shortValue();
            } else if (type == int.class || type == Integer.class) {
                return number.intValue();
            } else if (type == long.class || type == Long.class) {
                return number.longValue();
            } else if (type == float.class || type == Float.class) {
                return number.floatValue();
            } else if (type == double.class || type == Double.class) {
                return number.doubleValue();
            } else if (type == BigInteger.class) {
                return BigInteger.valueOf(number.longValue());
            } else if (type == BigDecimal.class) {
                return BigDecimal.valueOf(number.doubleValue());
            } else if (type == Date.class) {
                return new Date(number.longValue());
            }
        } else if(value instanceof Collection) {
            Collection collection = (Collection) value;
            if (type.isArray()) {
                int length = collection.size();
                Object array = Array.newInstance(type.getComponentType(), length);
                int i = 0;
                for (Object item : collection) {
                    Array.set(array, i ++, item);
                }
                return array;
            } else if (! type.isInterface()) {
                try {
                    Collection result = (Collection) type.newInstance();
                    result.addAll(collection);
                    return result;
                } catch (Throwable e) {
                }
            } else if (type == List.class) {
                return new ArrayList<Object>(collection);
            } else if (type == Set.class) {
                return new HashSet<Object>(collection);
            }
        } else if(value.getClass().isArray() && Collection.class.isAssignableFrom(type)) {
            Collection collection;
            if (! type.isInterface()) {
                try {
                    collection = (Collection) type.newInstance();
                } catch (Throwable e) {
                    collection = new ArrayList<Object>();
                }
            } else if (type == Set.class) {
                collection = new HashSet<Object>();
            } else {
                collection = new ArrayList<Object>();
            }
            int length = Array.getLength(value);
            for (int i = 0; i < length; i ++) {
                collection.add(Array.get(value, i));
            }
            return collection;
        }
        return value;
    }
}