转自http://blog.youkuaiyun.com/anroidfinalbreak/article/details/33728589
五、综合应用
下面通过最近写的一个随机数工具类来展示用法:
import java.util.Random;
public class RandomUtils
{
public static final String allChar = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
public static final String letterChar = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
public static final String numberChar = "0123456789";
public static String generateString(int length)
{
StringBuffer sb = new StringBuffer();
Random random = new Random();
for (int i = 0; i < length; i++) {
sb.append(allChar.charAt(random.nextInt(allChar.length())));
}
return sb.toString();
}
public static String generateMixString(int length)
{
StringBuffer sb = new StringBuffer();
Random random = new Random();
for (int i = 0; i < length; i++)
{
sb.append(allChar.charAt(random.nextInt(letterChar.length())));
}
return sb.toString();
}
public static String generateLowerString(int length)
{
return generateMixString(length).toLowerCase();
}
public static String generateUpperString(int length)
{
return generateMixString(length).toUpperCase();
}
public static String generateZeroString(int length)
{
StringBuffer sb = new StringBuffer();
for (int i = 0; i < length; i++)
{
sb.append('0');
}
return sb.toString();
}
public static String toFixdLengthString(long num, int fixdlenth)
{
StringBuffer sb = new StringBuffer();
String strNum = String.valueOf(num);
if (fixdlenth - strNum.length() >= 0)
{
sb.append(generateZeroString(fixdlenth - strNum.length()));
}
else
{
throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常!");
}
sb.append(strNum);
return sb.toString();
}
public static String toFixdLengthString(int num, int fixdlenth)
{
StringBuffer sb = new StringBuffer();
String strNum = String.valueOf(num);
if (fixdlenth - strNum.length() >= 0)
{
sb.append(generateZeroString(fixdlenth - strNum.length()));
} else {
throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常!");
}
sb.append(strNum);
return sb.toString();
}
public static void main(String[] args)
{
System.out.println(generateString(15));
System.out.println(generateMixString(15));
System.out.println(generateLowerString(15));
System.out.println(generateUpperString(15));
System.out.println(generateZeroString(15));
System.out.println(toFixdLengthString(123, 15));
System.out.println(toFixdLengthString(123L, 15));
}
}
运行结果:
vWMBPiNbzfGCpHG
23hyraHdJkKPwMv
tigowetbwkm1nde
BPZ1KNEJPHB115N
000000000000000
000000000000123
000000000000123