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： [email protected]<b style="color:transparent">来源gao@!dai!ma.com搞$$代^@码!网</b>m * */ 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 = 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 = 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 } }