java 驼峰转换

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将"_"转换成驼峰，将驼峰转换成"_"。

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * 驼峰转换
 * @author 胡汉三
 * 2017年1月19日 下午4:42:58
 */
public class BeanHump {
	
	//转变的依赖字符
	public static final char UNDERLINE='_';
	
	/**
	 * 将驼峰转换成"_"(userId:user_id)
	 * @param param
	 * @return
	 */
	public static String camelToUnderline(String param){  
		if (param==null||"".equals(param.trim())){  
			return "";  
		}  
		int len=param.length();  
		StringBuilder sb=new StringBuilder(len);  
		for (int i = 0; i < len; i++) {  
			char c=param.charAt(i);  
			if (Character.isUpperCase(c)){  
				sb.append(UNDERLINE);  
				sb.append(Character.toLowerCase(c));  
			}else{  
				sb.append(c);  
			}  
		}  
		return sb.toString();  
	}
	/**
	 * 将"_"转成驼峰(user_id:userId)
	 * @param param
	 * @return
	 */
	public static String underlineToCamel(String param){  
		if (param==null||"".equals(param.trim())){  
			return "";  
		}  
		int len=param.length();  
		StringBuilder sb=new StringBuilder(len);  
		for (int i = 0; i < len; i++) {  
			char c=param.charAt(i);  
			if (c==UNDERLINE){  
				if (++i<len){  
					sb.append(Character.toUpperCase(param.charAt(i)));  
				}  
			}else{  
				sb.append(c);  
			}  
		}  
		return sb.toString();  
	}
	/**
	 * 将"_"转成驼峰(user_id:userId)
	 * @param param
	 * @return
	 */
	public static String underlineToCamel2(String param){  
		if (param==null||"".equals(param.trim())){  
			return "";  
		}  
		StringBuilder sb=new StringBuilder(param);  
		Matcher mc= Pattern.compile(UNDERLINE+"").matcher(param);  
		int i=0;  
		while (mc.find()){  
			int position=mc.end()-(i++);  
			String.valueOf(Character.toUpperCase(sb.charAt(position)));  
			sb.replace(position-1,position+1,sb.substring(position,position+1).toUpperCase());  
		}  
		return sb.toString();  
	} 
	
	/*
	 * 测试
	 */
	public static void main(String[] args) {
		System.out.println(camelToUnderline("userNameAll"));
		System.out.println(underlineToCamel("user_name_all"));
		System.out.println(underlineToCamel2("user_name_all"));
	}
}

运行结果：