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
* */
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
}
}