Java sends the mail instance code with the html tag content

As follows:

package test;

import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeUtility;
import javax.mail.Session;
import javax.mail.MessagingException;
import javax.mail.Transport;

public class SendHtmlMail {
  public static void sendMessage(String smtpHost, String from, String to,String subject, String messageText) throws MessagingException,
      java.io.UnsupportedEncodingException {

    // Step 1: Configure the mail session
    System.out.println("Configuring mail session for: " + smtpHost);
    java.util.Properties props = new java.util.Properties();
    props.setProperty("mail.smtp.auth", "true");//  Specify whether or not SMTP validation 
    props.setProperty("mail.smtp.host", smtpHost);//  The specified SMTP The server 
    props.put("mail.transport.protocol", "smtp");
    Session mailSession = Session.getDefaultInstance(props);
    mailSession.setDebug(false);//  Whether to display in the console debug information 

    // Step 2: Construct the message
    System.out.println("Constructing message - from=" + from + " to=" + to);
    InternetAddress fromAddress = new InternetAddress(from);
    InternetAddress toAddress = new InternetAddress(to);

    MimeMessage testMessage = new MimeMessage(mailSession);
    testMessage.setFrom(fromAddress);
    testMessage.addRecipient(javax.mail.Message.RecipientType.TO, toAddress);
    testMessage.setSentDate(new java.util.Date());
    testMessage.setSubject(MimeUtility.encodeText(subject, "gb2312", "B"));

    testMessage.setContent(messageText, "text/html;charset=gb2312");
    System.out.println("Message constructed");

    // Step 3: Now send the message
    Transport transport = mailSession.getTransport("smtp");
    transport.connect(smtpHost, "riteng_mes", "ri-teng1234");
    transport.sendMessage(testMessage, testMessage.getAllRecipients());
    transport.close();

    System.out.println("Message sent!");
  }

  public static void main(String[] args) {

    String smtpHost = "10.131.119.36";
    String from = "Riteng_Mes@casetekcorp.com";
    String to = "Qiang1_Zhang@intra.casetekcorp.com";
    String subject = "html Mail test "; // subject javamail Automatic transcoding 

    StringBuffer theMessage = new StringBuffer();
    theMessage.append("<h2><font color=red> The poor boy </font></h2>");
    theMessage.append("<hr>");
    theMessage.append("<i> Year after year of disappointment </i>");
    theMessage.append("<table border='1'><tr><td>aaa</td><td>bbb</td></tr><tr><td>ccc</td><td>ddd</td></tr></table>");

    try {
      SendHtmlMail.sendMessage(smtpHost, from, to, subject,theMessage.toString());
    } catch (javax.mail.MessagingException exc) {
      exc.printStackTrace();
    } catch (java.io.UnsupportedEncodingException exc) {
      exc.printStackTrace();
    }
  }
}