java MD5 加密

package org.fh.util;
import java.security.MessageDigest;
/**
 * 说明：MD5处理
 * 作者：FH Admin
 * from：fhadmin.org
 */
public class MD5 {
    public static String md5(String str) {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(str.getBytes());
            byte b[] = md.digest();
            int i;
            StringBuffer buf = new StringBuffer("");
            for (int offset = 0; offset < b.length; offset++) {
                i = b[offset];
                if (i < 0)
                    i += 256;
                if (i < 16)
                    buf.append("0");
                buf.append(Integer.toHexString(i));
            }
            str = buf.toString();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return str;
    }
    public static void main(String[] args) {
        System.out.println(md5("313596790"+"123456"));
        System.out.println(md5("mj1"));
    }
}