java生成随机字符串（密码）包含字母，数字，a-z,A-Z,0-9

心已赠人 2022-04-11 09:30 732阅读 0赞

import java.util.Random;
    import java.util.UUID;
    
    /**
     * 生产指定长度随机字符串a-z,A-Z,0-9
     * @author happyqing
     * @since 2016.5.30
     */
    public class RandomString {
    
    	/**
    	 * 获取随机字符串 a-z,A-Z,0-9
    	 * @param length	长度
    	 * @return
    	 */
    	public static String getRandomString(int length) {
    		String str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    		Random random = new Random();
    		StringBuffer sb = new StringBuffer();
    
    		for (int i = 0; i < length; ++i) {
    			//int number = random.nextInt(62);// [0,62)
    			sb.append(str.charAt(random.nextInt(62)));
    		}
    		return sb.toString();
    	}
    	
    	/**
    	 * JAVA获得0-9,a-z,A-Z范围的随机数
    	 * 
    	 * @param length
    	 *            随机数长度
    	 * @return String
    	 */
    	public static String getRandomChar(int length) {
    		char[] chr = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 
    				'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 
    				'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
    		Random random = new Random();
    		StringBuffer buffer = new StringBuffer();
    		for (int i = 0; i < length; i++) {
    			buffer.append(chr[random.nextInt(62)]);
    		}
    		return buffer.toString();
    	}
    	
    	/**
    	 * 获取随机字符串 a-z
    	 * @param length	长度
    	 * @return
    	 */
    	public static String getLowerLetter(int length) {
    		String str = "abcdefghijklmnopqrstuvwxyz";
    		Random random = new Random();
    		StringBuffer sb = new StringBuffer();
    		for (int i = 0; i < length; ++i) {
    			sb.append(str.charAt(random.nextInt(26)));
    		}
    		return sb.toString();
    	}
    	
    	/**
    	 * 获取随机字符串 0-9
    	 * @param length	长度
    	 * @return
    	 */
    	public static String getNumber(int length) {
    		String str = "0123456789";
    		Random random = new Random();
    		StringBuffer sb = new StringBuffer();
    		for (int i = 0; i < length; ++i) {
    			sb.append(str.charAt(random.nextInt(10)));
    		}
    		return sb.toString();
    	}
    	
    	/**
    	 * 获取随机字符串 0-9,a-z,0-9
    	 * 有两遍0-9，增加数字概率
    	 * @param length	长度
    	 * @return
    	 */
    	public static String getLowerLetterNumber(int length) {
    		String str = "0123456789abcdefghijklmnopqrstuvwxyz0123456789";
    		Random random = new Random();
    		StringBuffer sb = new StringBuffer();
    		for (int i = 0; i < length; ++i) {
    			sb.append(str.charAt(random.nextInt(46)));
    		}
    		return sb.toString();
    	}
    	
    	/**
    	 * 获取随机密码，lLength位小写英文+nLength位数字
    	 * @param lLength	字母长度
    	 * @param nLength	数字长度
    	 * @return
    	 */
    	public static String getPasswordSimple(int lLength, int nLength) {
    		return getLowerLetter(lLength)+getNumber(nLength);
    	}
    	
    	/**
    	 * 获取随机密码，包含英文和数字
    	 * @param length 密码长度
    	 * @return
    	 */
    	public static String getPasswordComplex(int length) {
    		String password;
    		while(true){
    			password = getLowerLetterNumber(6);
    			//必须包含字母和数字
                if (password.matches("(?![0-9]+$)(?![a-zA-Z]+$)[0-9A-Za-z]{6,20}")) {
                    return password;
                }
            }
    	}
    
    	public static void main(String[] args) {
    //		System.out.println(getRandomString(32));
    //		System.out.println(getRandomChar(32));
    //		//UUID
    //		String uuid = UUID.randomUUID().toString().replaceAll("-", "");
    //		System.out.println(uuid);
    		
    		System.out.println(getPasswordSimple(1,5));
    		System.out.println(getPasswordComplex(6));
    	}
    }