cn.schoolwow.quickdao.util.StringUtil Maven / Gradle / Ivy

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package cn.schoolwow.quickdao.util;

public class StringUtil {
    /**
     * 驼峰命名转下划线命名
     */
    public static String camel2Underline(String s) {
        if (s == null || s.isEmpty()) {
            return s;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            if (i == 0 && s.charAt(i) >= 65 && s.charAt(i) <= 90) {
                sb.append((char) (s.charAt(i) + 32));
                continue;
            }
            if (s.charAt(i) >= 65 && s.charAt(i) <= 90) {
                //如果它前面是小写字母
                if (s.charAt(i - 1) >= 97 && s.charAt(i - 1) <= 122) {
                    sb.append("_");
                }
                sb.append((char) (s.charAt(i) + 32));
            } else {
                sb.append(s.charAt(i));
            }
        }
        return sb.toString();
    }

    /**
     * 下划线命名转驼峰命名
     */
    public static String underline2Camel(String s) {
        StringBuilder sb = new StringBuilder();
        //以下划线分割
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == '_') {
                continue;
            }
            if (i > 0 && s.charAt(i - 1) == '_') {
                //如果当前是小写字母则转大写
                if (s.charAt(i) >= 97 && s.charAt(i) <= 122) {
                    sb.append((char) (s.charAt(i) - 32));
                } else {
                    sb.append(s.charAt(i));
                }
            } else {
                sb.append(s.charAt(i));
            }
        }
        return sb.toString();
    }

    /**
     * 首字母大写
     */
    public static String firstLetterUpper(String s) {
        char firstLetter = s.charAt(0);
        if (firstLetter >= 97 && firstLetter <= 122) {
            firstLetter -= 32;
        }
        return firstLetter + s.substring(1);
    }
}