/**
* 各種隨機字串生成的方法
*
* @author Administrator
*
*/
public class RandomString {
public static final String ALLCHAR = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
public static final String LETTERCHAR = "abcdefghijkllmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
public static final String NUMBERCHAR = "0123456789"
 
;
/**
* 返回一個定長的隨機字串(包含大小寫字母、數字)
*
* @param length
* 隨機字串長度
* @return 隨機字串
*/
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();
}
/**
* 返回一個定長的隨機純字母字串(只包含大小寫字母)
*
* @param
 
 length
* 隨機字串長度
* @return 隨機字串
*/
public static String generateUpperLowerString(int length) {
StringBuffer sb = new StringBuffer();
Random random = new Random();
for (int i = 0; i < length; i++) {
sb.append(LETTERCHAR.charAt(random.nextInt(LETTERCHAR.length())));
}
return sb.toString();
}
/**
* 返回一個定長的隨機純小寫字母字串(只包含小寫字母)
*
* @param
 
 length
* 隨機字串長度
* @return 隨機字串
*/
public static String generateLowerString(int length) {
return generateUpperLowerString(length).toLowerCase();
}
/**
* 返回一個定長的隨機純大寫字母字串(只包含大寫字母)
*
* @param length
* 隨機字串長度
* @return 隨機字串
*/
public static String generateUpperString(int length) {
return generateUpperLowerString(length).toUpperCase();
}
/**
* 生成一個定長的純0字串
*
* @param length
* 字串長度
* @return 純0字串
*/
public static String generateZeroString(int length) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < length; i++) {
sb.append('0');
}
return sb.toString();
}
/**
* 根據數字生成一個定長的字串，長度不夠前面補0
*
* @param num
* 數字
* @param fixdlenth
* 字串長度
* @return 定長的字串
*/
public static String generateFixdLengthString(long num, int fixedlenth) {
StringBuffer sb = new StringBuffer();
String strNum = String.valueOf(num);
if (fixedlenth - strNum.length() >= 0) {
sb.append(generateZeroString(fixedlenth - strNum.length()));
} else {
throw new RuntimeException("將數字" + num + "轉化為長度為" + fixedlenth
+ "的字串發生異常！");
}
sb.append(strNum);
return sb.toString();
}
/**
* 每次生成的len位數都不相同(僅限於整型陣列的每個元素都0-9這十個基本數字，且len的值還不能大於陣列的長度)
*
* @param param
* @return 定長的數字
*/
public static int generateDifferentNum(int[] param, int len) {
Random rand = new Random();
for (int i = param.length; i > 1; i--) {
int index = rand.nextInt(i);
int tmp = param[index];
param[index] = param[i - 1];
param[i - 1] = tmp;
}
int result = 0;
for (int i = 0; i < len; i++) {
result = result * 10 + param[i];
}
return result;
}
}