加密工具，base64加密、sha256加密、MD5加密

import sun.misc.BASE64Encoder;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 
 * 加密工具
 * 
 * @author  jy
 * @version  [版本号, 2018-7-22]
 * @see  [相关类/方法]
 * @since  [产品/模块版本]
 */
public class EncryptUtil
{
    /**
     * base64加密
     * 
     * @param bt 被sha256加密过后的byte
     * @return
     * @see [类、类#方法、类#成员]
     */
    public static String base64(byte[] bt){
        String s = null;
        if (null != bt) {
            s = new BASE64Encoder().encode(bt);
        }
        return s;
    }
    /**
     * sha256加密
     * 
     * @param param  加密的参数
     * @return
     * @throws NoSuchAlgorithmException
     * @see [类、类#方法、类#成员]
     */
    public static byte[] SHA256(String param)
        throws NoSuchAlgorithmException{
        byte[] bt = param.getBytes();
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(bt);
        return md.digest();
    }
/**
     * md5加密
     * 
     * @param param  加密的参数
     * @return
     * @throws NoSuchAlgorithmException
     * @see [类、类#方法、类#成员]
     */
public final static String GetMD5Code(StringBuffer data) {//StringBuffer类型
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(data.toString().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));
            }
            return buf.toString().toUpperCase();

        } catch (NoSuchAlgorithmException e) {
            // TODO Auto-generated catch block
            return null;
        }
    }

    public final static String GetMD5Code(String data) {//String类型，统一utf-8
        try {
            byte[] btInput = data.getBytes("UTF-8");
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(btInput);
            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));
            }
            return buf.toString().toUpperCase();

        } catch (Exception e) {
            // TODO Auto-generated catch block
            return null;
        }
    }

    public final static String GetMD5_16Code(String data) {//String类型，只取部分数据
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(data.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));
            }
            return buf.toString().toUpperCase().substring(8,24);

        } catch (NoSuchAlgorithmException e) {
            return null;
        }
    }
}

总结：具体出处均来自网上。