Java 大小写最快转换方式

package io.mycat;

import java.util.stream.IntStream;
/**
 * 小写字母的 'a'=97 大写字母 A=65 更好相差32利用这个差进行大小写转换
 * @author : Hpgary
 * @date : 2017年5月3日 10:26:26
 * @mail： [e-mail]
 * */
public class StringUtils {

	protected final static byte[] CHAR_TYPE = new byte[512];

	protected final static byte CHARACTER_DIFFER = 32;

	static {
		/**
		 * 先将大写字母放入 CHAR_TYPE 中，将大写转换成为小写字母
		 * */
		IntStream.rangeClosed('A', 'Z').forEach(c -> CHAR_TYPE[c] = (byte) (c + CHARACTER_DIFFER));
		/**
		 * 将小写字母放入 CHAR_TYPE，存值为小写字母
		 * */
		IntStream.rangeClosed('a', 'z').forEach(c -> CHAR_TYPE[c] = (byte) (c));
	}
	
	public static byte[] toUpperCase(String src) {
		byte[] bytes = src.getBytes();
		for (int x = 0; x < bytes.length; x++) {
			int tmpLen = bytes[x] << 1;
			if (tmpLen < CHAR_TYPE.length && tmpLen >= 0) {
				byte b = CHAR_TYPE[bytes[x]];
				if (b != 0) {
					bytes[x] = (byte) (b - CHARACTER_DIFFER);
				}
			}
		}
		return bytes;
	}

	public static byte[] toLowerCase(String src) {
		byte[] bytes = src.getBytes();
		for (int x = 0; x < bytes.length; x++) {
			int tmpLen = bytes[x] << 1;
			if (tmpLen < CHAR_TYPE.length && tmpLen >= 0) {
				byte b = CHAR_TYPE[bytes[x]];
				if (b != 0) {
					bytes[x] = b;
				}
			}
		}
		return bytes;
	}

	public static void main(String[] args) {
		int count = 100000 ; 
		String str = "fdajfadSKfj1221SDKfdasfdsafjdsafjlsadjfkl;sdajflksadjlfkjasdlk;fjasdklfasdA" ;
		
		long time2 = System.currentTimeMillis();
		for (int x = 0; x < count; x++) {
			str.toUpperCase();
		}
		System.out.println(System.currentTimeMillis() - time2);  //51 - 53
		
		long time1 = System.currentTimeMillis();
		for (int x = 0; x < count; x++) {
			toUpperCase(str) ; 
		}
		System.out.println(System.currentTimeMillis() - time1); // 35-37
	}
}