Java 大小写最快转换方式实例代码

Java 大小写最快转换方式实例代码

         这里直接给出实现代码，在代码中注释都很清楚，不多做介绍。

Java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 
  } 
} 

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