import java.util.Random;
public class RandomTest { /** * 方法1：生成随机数字和字母组合 * @param length * @return */ public static String getCharAndNumr(int length) { Random random = new Random(); StringBuffer valSb = new StringBuffer(); String charStr = "0123456789abcdefghijklmnopqrstuvwxyz"; int charLength = charStr.length(); for (int i = 0; i < length; i++) { int index = random.nextInt(charLength); valSb.append(charStr.charAt(index)); } return valSb.toString(); } /** * 方法2：生成随机数字和字母组合 * @param length * @return */ public static String getCharAndNumr2(int length) { StringBuffer valSb = new StringBuffer(); Random random = new Random(); for (int i = 0; i < length; i++) { String charOrNum = random.nextInt(2) % 2 == 0 ? "char" : "num"; // 输出字母还是数字 if ("char".equalsIgnoreCase(charOrNum)) { // 字符串 int choice = random.nextInt(2) % 2 == 0 ? 65 : 97; // 取得大写字母还是小写字母 valSb.append((char) (choice + random.nextInt(26))); } else if ("num".equalsIgnoreCase(charOrNum)) { // 数字 valSb.append(String.valueOf(random.nextInt(10))); } } return valSb.toString(); } /** * 方法3：生成随机数字和字母组合 * @param length * @return */ public static String getCharAndNumr3(int length) { StringBuffer valSb = new StringBuffer(); for (int i = 0; i < length; i++) { String charOrNum = Math.round(Math.random()) % 2 == 0 ? "char" : "num"; // 输出字母还是数字 if ("char".equalsIgnoreCase(charOrNum)) { // 字符串 int choice = Math.round(Math.random()) % 2 == 0 ? 65 : 97; // 取得大写字母还是小写字母 valSb.append((char) (choice + Math.round(Math.random()*25))); } else if ("num".equalsIgnoreCase(charOrNum)) { // 数字 valSb.append(String.valueOf(Math.round(Math.random()*9))); } } return valSb.toString(); } }