Java string utility functions, with some from the internet

java_string_ex

package com.newcoresys.utils;

import java.util.Arrays;
import java.util.List;

/**
 * @Description: 字符串处理工具类
 * @author: joeymac
 */
public class StringEx {
	
	
	/**
	 * 字符串首字母小写
	 * 
	 * @param str
	 * @return
	 */
	public static String toLowerCaseFirstOne(String str) {
		if (str == null || "".equals(str))
			return str;
		if (Character.isLowerCase(str.charAt(0)))
			return str;
		else
			return (new StringBuilder())
					.append(Character.toLowerCase(str.charAt(0)))
					.append(str.substring(1)).toString();
	}

	/**
	 * 字符串首字母大写
	 * 
	 * @param str
	 * @return
	 */
	public static String toUpperCaseFirstOne(String str) {
		if (str == null || "".equals(str))
			return str;
		if (Character.isUpperCase(str.charAt(0)))
			return str;
		else
			return (new StringBuilder())
					.append(Character.toUpperCase(str.charAt(0)))
					.append(str.substring(1)).toString();
	}

	/**
	 * 使用delimiter join字符串数组(默认capacity是32)
	 * 
	 * @param delimiter
	 * @param values
	 * @return
	 * @author joeymac
	 */
	public static String join(String delimiter, String... values) {
		return join(delimiter, Arrays.asList(values));
	}
	/**
	 * 使用delimiter join整型数组(默认capacity是32)
	 * 
	 * @param delimiter
	 * @param values
	 * @returnj
	 * @author joeymac
	 */
	public static String join(String delimiter, Integer... values) {
		return joinInteger(delimiter, Arrays.asList(values));
	}
	
	/**
	 * 使用delimiter join字符串数组(默认capacity是32)
	 * 
	 * @param delimiter
	 * @param values
	 * @return
	 * @author joeymac
	 */
	public static String join(String delimiter, List<String> values) {
		if (delimiter == null || values.size() == 0) {
			return "";
		}
		StringBuilder sb = new StringBuilder(32);
		for (int i = 0; i < values.size(); i++) {
			if (i != 0) sb.append(delimiter);
			if (values.get(i) != null) {
				sb.append(values.get(i));
			}
		}
		return sb.toString();
	}
	/**
	 * 使用delimiter join整型数组(默认capacity是32)
	 * 
	 * @param delimiter
	 * @param values
	 * @return
	 * @author joeymac
	 */
	public static String joinInteger(String delimiter, List<Integer> values) {
		if (delimiter == null || values.size() == 0) {
			return "";
		}
		StringBuilder sb = new StringBuilder(32);
		for (int i = 0; i < values.size(); i++) {
			if (i != 0) sb.append(delimiter);
			if (values.get(i) != null) {
				sb.append(values.get(i));
			}
		}
		return sb.toString();
	}
	
	
	/**
	 * 判断字符串是不是null
	 * @param str
	 * @return
	 */
	public static boolean isNull(String str) {
		return str == null;
	}
	
    public static byte[] charToByte(char ch) {  
        int temp = (int) ch;  
        byte[] b = new byte[2];  
        // 将高8位放在b[0],将低8位放在b[1]  
        for (int i = 1; i > -1; i--) {  
            b[i] = (byte) (temp & 0xFF);// 低8位  
            // 向右移8位  
            temp >>= 8;  
        }  
        return b;  
    }  
  
    // 将字节转化为比特数组  
    public static byte[] byteToBitArray(byte b) {  
        // 强制转换成int?  
        int temp = (int) b;  
        byte[] result = new byte[8];  
        for (int i = 7; i > -1; i--) {  
            result[i] = (byte) (temp & 0x01);  
            temp >>= 1;  
        }  
        return result;  
    }  
  
    // 将二维比特数组转化为字节  
    public static byte bitToByteArray(byte[] b) {  
        byte result;  
        result = (byte) (b[7] | b[6] << 1 | b[5] << 2 | b[4] << 3 | b[3] << 4  
                | b[2] << 5 | b[1] << 6 | b[0] << 7);  
        return result;  
    } 
  
    // 将字节转化为字符  
    public static char byteToChar(byte[] b) {  
        int s = 0;  
        if (b[0] > 0) {  
            s += b[0];  
        }  
        if (b[0] < 0) {  
            s += 256 + b[0];  
        }  
        s *= 256;  
        if (b[1] > 0) {  
            s += b[1];  
        }  
        if (b[1] < 0) {  
            s += 256 + b[1];  
        }  
        char ch = (char) s;  
        return ch;  
    }  
  
    public static String byteToHexString(byte b) {  
        String hex = "";  
        hex = Integer.toHexString(b & 0xFF);  
        if (hex.length() == 1) {  
            hex = '0' + hex;  
        }  
        return hex;  
    }  
  
    public static String bytesToHexString(byte[] bs) {  
        StringBuffer sb = new StringBuffer();  
        String hex = "";  
        for (int i = 0; i < bs.length; i++) {  
            hex = Integer.toHexString(bs[i] & 0xFF);  
            if (hex.length() == 1) {  
                hex = '0' + hex;  
            }  
            sb.append(hex);  
        }  
        return sb.toString();  
    }  

    public static byte[] hexStringToBytes(String in) {  
        byte[] arrB;
        try {
    		arrB = in.getBytes("UTF-8");
            int iLen = arrB.length;  
            // 两个字符表示一个字节，所以字节数组长度是字符串长度除以2  
            byte[] arrOut = new byte[iLen / 2];  
            for (int i = 0; i < iLen; i = i + 2) {  
                String strTmp = new String(arrB, i, 2);  
                arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);  
            }  
            return arrOut; 
		} catch (Exception e) {
			e.printStackTrace();
		}
        return null;
    }

    public static void main(String[] args) {  
    	System.out.println(hexStringToBytes("000a0a0a0a0202aa000a0a0a0a0202aa"));
    } 
    
}