MD5加密

package AddSalt;
import java.security.MessageDigest;
import java.util.Random;
 
public class MD5Utils {
 
  /**
     * byte[]字节数组 转换成 十六进制字符串
     * 
     * @param arr 要转换的byte[]字节数组
     *
     * @return  String 返回十六进制字符串
     */
     private static String hex(byte[] arr) {
	     StringBuffer sb = new StringBuffer();
	     for (int i = 0; i < arr.length; ++i) {
		     sb.append(Integer.toHexString((arr[i] & 0xFF) | 0x100).substring(1, 3));
	     }
	     return sb.toString();
     }
 
 
 
 
   /**
     * MD5加密,并把结果由字节数组转换成十六进制字符串
     * 
     * @param str 要加密的内容
     * 
     * @return String 返回加密后的十六进制字符串
     */
     private static String md5Hex(String str) {
       try {
           MessageDigest md = MessageDigest.getInstance("MD5");
           byte[] digest = md.digest(str.getBytes());
           return hex(digest);
       } catch (Exception e) {
           e.printStackTrace();
           System.out.println(e.toString());
           return "";
       }
     }
 
 
 
   /**
     * 生成含有随机盐的密码
     *
     * @param password 要加密的密码
     *
     * @return String 含有随机盐的密码
     */
     public static String getSaltMD5(String password) {
		// 生成一个16位的随机数
        Random random = new Random();
        StringBuilder sBuilder = new StringBuilder(16);
        sBuilder.append(random.nextInt(99999999)).append(random.nextInt(99999999));
        int len = sBuilder.length();
        if (len < 16) {
              for (int i = 0; i < 16 - len; i++) {
                sBuilder.append("0");
            }
        }
        // 生成最终的加密盐
        String salt = sBuilder.toString();
        password = md5Hex(password + salt);
        char[] cs = new char[48];
        for (int i = 0; i < 48; i += 3) {
            cs[i] = password.charAt(i / 3 * 2);
            char c = salt.charAt(i / 3);
            cs[i + 1] = c;
            cs[i + 2] = password.charAt(i / 3 * 2 + 1);
        }
        System.out.println("String.valueOf(cs)======="+String.valueOf(cs));
        return String.valueOf(cs);
     }
 
 
 
   /**
     * 验证加盐后是否和原密码一致
     * 
     * @param password 原密码
     * 
     * @param password 加密之后的密码
     * 
     *@return boolean true表示和原密码一致   false表示和原密码不一致
     */
     public static boolean getSaltverifyMD5(String password, String md5str) {
        char[] cs1 = new char[32];
        char[] cs2 = new char[16];
        for (int i = 0; i < 48; i += 3) {
            cs1[i / 3 * 2] = md5str.charAt(i);
            cs1[i / 3 * 2 + 1] = md5str.charAt(i + 2);
            cs2[i / 3] = md5str.charAt(i + 1);
        }
       
        String Salt = new String(cs2);
        return md5Hex(password + Salt).equals(String.valueOf(cs1));
     }
 
 
    
    public static void main(String[] args) {
        // 原密码
        String plaintext = "123456";
 
        // 获取加盐后的MD5值
        String ciphertext = MD5Utils.getSaltMD5(plaintext);
        System.out.println("加盐后MD5：" + ciphertext);
        System.out.println("是否是同一字符串:" + MD5Utils.getSaltverifyMD5(plaintext, ciphertext));
    }
}