Java 常用字符串操作函数

/**
   * 分割字符串
   *
   * @param str String 原始字符串
   * @param splitsign String 分隔符
   * @return String[] 分割后的字符串数组
   */
@SuppressWarnings("unchecked")
public static String[] split(String str, String splitsign) {
    int index;
    if (str == null || splitsign == null)
      return null;
    ArrayList al = new ArrayList();
    while ((index = str.indexOf(splitsign)) != -1) {
      al.add(str.substring(0, index));
      str = str.substring(index + splitsign.length());
    }
    al.add(str);
    return (String[]) al.toArray(new String[0]);
}

/**
   * 替换字符串
   *
   * @param from String 原始字符串
   * @param to String 目标字符串
   * @param source String 母字符串
   * @return String 替换后的字符串
   */
public static String replace(String from, String to, String source) {
    if (source == null || from == null || to == null)
      return null;
    StringBuffer bf = new StringBuffer("");
    int index = -1;
    while ((index = source.indexOf(from)) != -1) {
      bf.append(source.substring(0, index) + to);
      source = source.substring(index + from.length());
      index = source.indexOf(from);
    }
    bf.append(source);
    return bf.toString();
}

/**
   * 替换字符串，能能够在HTML页面上直接显示(替换双引号和小于号)
   *
   * @param str String 原始字符串
   * @return String 替换后的字符串
   */
public static String htmlencode(String str) {
    if (str == null) {
      return null;
    }

    return replace("\\"", """, replace("<", "<",="" str));="" }="" **="" *="" 替换字符串，将被编码的转换成原始码（替换成双引号和小于号）="" @param="" str="" string="" @return="" public="" static="" htmldecode(string="" str)="" {="" if="" (str="=" null)="" return="" null;="" replace(""",="" "\\"",="" replace("<",="" private="" final="" _br="
" ;="" 在页面上直接显示文本内容，替换小于号，空格，回车，tab="" 原始字符串="" 替换后的字符串="" htmlshow(string="" str);="" ",="" "="" _br,="" str;="" 返回指定字节长度的字符串="" 字符串="" length="" int="" 指定长度="" 返回的字符串="" tolength(string="" str,="" length)="" (length="" <="0)" "";="" try="" (str.getbytes("gbk").length="" catch="" (exception="" ex)="" stringbuffer="" buff="new" stringbuffer();="" index="0;" char="" c;="" -="3;" while=""> 0) {
      c = str.charAt(index);
      if (c < 128) {
        length--;
      } else {
        length--;
        length--;
      }
      buff.append(c);
      index++;
    }
    buff.append("...");
    return buff.toString();
}

/**
   * 判断是否为整数
   *
   * @param str 传入的字符串
   * @return 是整数返回true,否则返回false
   */
public static boolean isInteger(String str) {
    Pattern pattern = Pattern.compile("^[-\\\\+]?[\\\\d]*$");
    return pattern.matcher(str).matches();
}

/**
   * 判断是否为浮点数，包括double和float
   *
   * @param str 传入的字符串
   * @return 是浮点数返回true,否则返回false
   */
public static boolean isDouble(String str) {
    Pattern pattern = Pattern.compile("^[-\\\\+]?[.\\\\d]*$");
    return pattern.matcher(str).matches();
}

/**
   * 判断输入的字符串是否符合Email样式.
   *
   * @param str 传入的字符串
   * @return 是Email样式返回true,否则返回false
   */
public static boolean isEmail(String str) {
    Pattern pattern = Pattern.compile("^\\\\w+([-+.]\\\\w+)*@\\\\w+([-.]\\\\w+)*\\\\.\\\\w+([-.]\\\\w+)*$");
    return pattern.matcher(str).matches();
}

/**
   * 判断输入的字符串是否为纯汉字
   *
   * @param str 传入的字符窜
   * @return 如果是纯汉字返回true,否则返回false
   */
public static boolean isChinese(String str) {
    Pattern pattern = Pattern.compile("[\\u0391-\\uFFE5]+$");
    return pattern.matcher(str).matches();
}

/**
   * 是否为空白,包括null和""
   *
   * @param str
   * @return
   */
public static boolean isBlank(String str) {
    return str == null || str.trim().length() == 0;
}

/**
* 判断是不是合法手机
* handset 手机号码
*/
public static boolean isHandset(String handset) {
try {
   if(!handset.substring(0,1).equals("1")) {
    return false;
   }
   if (handset==null || handset.length()!=11) {
    return false;
   }
   String check = "^[0123456789]+$";
   Pattern regex = Pattern.compile(check);
   Matcher matcher = regex.matcher(handset);
   boolean isMatched = matcher.matches();
   if(isMatched) {
    return true;
   } else {
    return false;
   }
} catch (RuntimeException e) {
   return false;
}
}
}