Java 大小写最快转换方式实例代码

package io.mycat;  import java.util.stream.IntStream;  public class StringUtils {    protected final static byte[] CHAR_TYPE = new byte[512];    protected final static byte CHARACTER_DIFFER = 32;    static {          IntStream.rangeClosed('A', 'Z').forEach(c -> CHAR_TYPE[c] = (byte) (c + CHARACTER_DIFFER));          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   } }