Java实现驼峰、下划线互转的方法

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>21.0</version>
</dependency>
```1
1.1 驼峰转下划线
```java
 public static void main(String[] args) {
        String resultStr = CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, "userName");
        System.out.println("转换后结果是："+resultStr);
    }
    转换后结果是：user_name

public static void main(String[] args) {
        String resultStr = CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, "user_name");
        System.out.println("转换后结果是："+resultStr);
    }
    转换后结果是：userName

  private static final Pattern TPATTERN = Pattern.compile("[A-Z0-9]");
        private String teseDemo(String str) {
            Matcher matcher = TPATTERN.matcher(str);
            StringBuffer sb = new StringBuffer();
            while (matcher.find()) {
                matcher.appendReplacement(sb, "_" + matcher.group(0).toLowerCase());
            }
            matcher.appendTail(sb);
            return sb.toString();
        }

  private static final char UNICON = '_';
    private String underlineToCamel(String param) {
        if (StringUtils.isBlank(param)) {
            return "";
        }
        int len = param.length();
        StringBuilder sb = new StringBuilder(len);
        for (int i = 0; i < len; i++) {
            char c = Character.toLowerCase(param.charAt(i));
            if (c == UNICON) {
                if (++i < len) {
                    sb.append(Character.toUpperCase(param.charAt(i)));
                }
            } else {
                sb.append(c);
            }
        }
        return sb.toString();
    }