import org.apache.commons.lang3.StringUtils;

/**
 * @Author **
 * @Date 2021/10/5
 * @Description:
 */
public class DesensitizeUtil {

    /**
     * 姓名脱敏
     * @param str
     * @param index
     * @return
     */
    public static String left(String str,int index) {
        if (StringUtils.isBlank(str)) {
            return "";
        }
        String name = StringUtils.left(str, index);
        return StringUtils.rightPad(name, StringUtils.length(str), "*");
    }

}

测试：

public class Demo01 {
    public static void main(String[] args) {
        String name = "欧阳娜娜";
        String newName = DesensitizeUtil.left(name, 2);
        System.out.println(newName);
    }
}

结果：欧阳**