Java 大小写最快转换方式实例代码

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： hpgary@qq.com  * */ 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   } }