java 获取随机字符串

代码功能是获取指定长度的随机字符串：

package com.pingan.tools;

import java.util.Random;

/**
* 获取随机串
*/
public class RandomString {
private static final String SOURCE_STRING = "0123456789-_abcdefghigklmnopqrstuvwxyzABCDEFGHIGKLMNOPQRSTUVWXYZ";
private static final int DEFAULT_LENGTH = 16;

/**
* 获取默认长度的随机串，16位
* @return 随机串
*/
public String getRandomString() {
return this.createRandomString(SOURCE_STRING, DEFAULT_LENGTH);
}

/**
* 获取指定长度的随机字符串
* @param length 随机串的长度
* @return 随机串
*/
public String getRandomString(int length) {
return this.createRandomString(SOURCE_STRING, length);
}

/**
* 获取随机串
* @param source 源字符串
* @param length 随机串的长度
* @return 随机串
*/
private String createRandomString(String source, int length) {
if (this.isNullOrEmpty(source)) {
return "";
}

StringBuffer result = new StringBuffer();
Random random = new Random();

for(int index = 0; index < length; index++) {
result.append(source.charAt(random.nextInt(source.length())));
}

System.out.println(result.toString());
return result.toString();
}

/**
* 判断字符串是否为空
* @param target
* @return true：空，false：非空
*/
private boolean isNullOrEmpty(String target) {
if (null == target || "".equals(target) || target.isEmpty()) {
return true;
}
return false;
}
}