How to send a button instead of a link in an HTML email?

My app sends an email from my java code. I also want to send a link within a button which will say “Activate your account”.

Here is what I have:

Message message = new MimeMessage(sessionMail);
message.setFrom(new InternetAddress("[e-mail]"));
message.setRecipients(Message.RecipientType.TO,InternetAddress.parse(user.getEmailAddress()));
message.setSubject("Account Created");
message.setText("Dear"+ user.getUserName() 
                      +" " + "nn  Your  Account created," 
                      + "nnPlease activate your account" 
                      + "<a> www.test.eu:8080/Project/"
                      + user.getToken()+"</a>");
Transport.send(message);

The following line

+ "<a> www.test.eu:8080/Project/"+ user.getToken()+" 

works as a link right now, I just want to put this link in a button and send that button to user’s email.

Is there any solution for this?

I am trying this:

      message.setText("Dear"+ user.getUserName() +" "
    + "nn  Your Tie Account created,"

+ "nn Please activate your account" 
+ " <a href=www.example.eu:8080/TieProject/#!"+ user.getToken()+" >"
+" <button>Activate your Account</button> </a>"

    );

Answer

Try with something like

<a href="www.test.eu:8080/Project/"+ user.getToken()>

   <button>Activate your Account</button>

</a>