Java的驼峰与下划线的属性对象互相转换_JAVA_编程开发_程序员俱乐部

class="java" name="code">

import com.xxxx.util.constant.PropertyNameStyle;
import com.google.common.collect.Lists;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.MapUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.BeanUtils;
import org.springframework.util.ClassUtils;

import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;

@Slf4j
public class GenericPropertyConverter {

	public static final char UNDERLINE_CHAR = '_';

	public static <T> T convertObject(Object originObj, PropertyNameStyle originStyle, Class<T> targetClass) {

		return baseConvertObject(originObj, originStyle, targetClass, null, null);
	}

	public static <T, F> List<T> convertObject(List<F> originLst, PropertyNameStyle originStyle, Class<T> targetClass) {
		if (Objects.isNull(originLst)) {
			return null;
		}
		List<T> result = Lists.newArrayListWithCapacity(originLst.size());
		originLst.forEach(o -> result.add(convertObject(o, originStyle, targetClass)));
		return result;
	}

	/**
	 * 
	 * @param originObj 待转换的源对象，【不可为null】
	 * @param originStyle 源对象的property的命名风格，【不可为null】
	 * @param targetClass 目标对象，【不可为null】FieldNamingPolicy
	 * @param customizePropertyNameMap 自定义转换属性，【可为null】
	 * @param excludePropertyNameList 自定义的排除属性，【可为null】
	 * @return
	 */
	public static <T> T baseConvertObject(Object originObj, PropertyNameStyle originStyle, Class<T> targetClass,
			Map<String, String> customizePropertyNameMap, List<String> excludePropertyNameList) {

		T targetObj;
		try {
			targetObj = targetClass.newInstance();
		} catch (InstantiationException | IllegalAccessException e) {

			log.error("通用的风格属性名转换时出错\n{}", e.getMessage());
			return null;
		}

		Class<?> originClass = originObj.getClass();
		PropertyDescriptor[] originPds = BeanUtils.getPropertyDescriptors(originClass),
				targetPds = BeanUtils.getPropertyDescriptors(targetClass);
		Function<String, String> propertyConvertFunc = PropertyNameStyle.CAMEL.equals(originStyle)
				? GenericPropertyConverter::camel2Underline
				: GenericPropertyConverter::underline2Camel;
		for (PropertyDescriptor originPd : originPds) {

			String propertyName = originPd.getName();
			if ("class".equals(propertyName)) {

				continue;
			}
			
			if (CollectionUtils.isNotEmpty(excludePropertyNameList) && excludePropertyNameList.contains(propertyName)) {
				
				continue;
			}

			String newPropertyName = StringUtils.EMPTY;
			if (MapUtils.isNotEmpty(customizePropertyNameMap)) {
				
				newPropertyName = customizePropertyNameMap.get(propertyName);
			} 
			if (StringUtils.isBlank(newPropertyName)) {
				
				newPropertyName = propertyConvertFunc.apply(propertyName);
			}
			if (StringUtils.isBlank(newPropertyName)) {
				
				continue;
			}
			
			Class<?> originPropertyType = originPd.getPropertyType();
			for (PropertyDescriptor targetPd : targetPds) {

				if (newPropertyName.equals(targetPd.getName()) == false) {

					continue;
				}

				Method originReadMethod = originPd.getReadMethod(), 
						targetWriteMethod = targetPd.getWriteMethod();
				if (originReadMethod != null && targetWriteMethod != null
						&& ClassUtils.isAssignable(targetWriteMethod.getParameterTypes()[0], originPropertyType)) {

					try {
						if (Modifier.isPublic(originReadMethod.getDeclaringClass().getModifiers()) == false) {

							originReadMethod.setAccessible(true);
						}
						Object value = originReadMethod.invoke(originObj);
						if (Modifier.isPublic(targetWriteMethod.getDeclaringClass().getModifiers()) == false) {

							targetWriteMethod.setAccessible(true);
						}
						targetWriteMethod.invoke(targetObj, value);
					} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e1) {

						log.error("通用的风格属性名转换时出错\n{}", e1.getMessage());
						return null;
					}
				}
			}
		}
		return targetObj;
	}

	/**
	 * 驼峰转下划线
	 * 
	 * @param camelStr
	 * @return
	 */
	public static String camel2Underline(String camelStr) {

		if (StringUtils.isEmpty(camelStr)) {

			return StringUtils.EMPTY;
		}

		int len = camelStr.length();
		StringBuilder strb = new StringBuilder(len + len >> 1);
		for (int i = 0; i < len; i++) {

			char c = camelStr.charAt(i);
			if (Character.isUpperCase(c)) {

				strb.append(UNDERLINE_CHAR);
				strb.append(Character.toLowerCase(c));
			} else {

				strb.append(c);
			}
		}
		return strb.toString();
	}

	/**
	 * 下划线转驼峰
	 * 
	 * @param underlineStr
	 * @return
	 */
	public static String underline2Camel(String underlineStr) {

		if (StringUtils.isEmpty(underlineStr)) {

			return StringUtils.EMPTY;
		}

		int len = underlineStr.length();
		StringBuilder strb = new StringBuilder(len);
		for (int i = 0; i < len; i++) {

			char c = underlineStr.charAt(i);
			if (c == UNDERLINE_CHAR && (++i) < len) {

				c = underlineStr.charAt(i);
				strb.append(Character.toUpperCase(c));
			} else {

				strb.append(c);
			}
		}
		return strb.toString();
	}
}