对于Javamail的疑问,提供例子,大家可以试试我的代码

//现在的大部分的邮件服务器都要求有身份验证，所以需要此类实现验证功能
class MailAuthenticator extends Authenticator{    private String username = null;
    private String userpasswd = null;    public MailAuthenticator(){}
    public MailAuthenticator(String username,String userpasswd){
        this.username = username;
        this.userpasswd = userpasswd;
    }
    
    public void setUserName(String username){
        this.username = username;
    }    public void setPassword(String password){
        this.userpasswd = password;
    }    public PasswordAuthentication getPasswordAuthentication(){
        return new PasswordAuthentication(username,userpasswd);
    }
}//为了使此邮件发送程序能够支持可扩展性，把发送邮件的类型放到子类中来，
//以便支持更多的邮件类型,比如语音邮件，视频邮件等......//1.发送纯文本文件的的子类MailSendText.classclass MailSendText extends SendMail{    public MailSendText(String smtpHost,String username,String password){
        super(smtpHost,username,password);
        multipart = new MimeMultipart();
    }    public void setMailContent(String mailContent)throws MessagingException{
        messageBodyPart.setText(mailContent);
        multipart.addBodyPart(messageBodyPart);
       
    }
}//2.发送html格式的子类MailSendHtml.class
class MailSendHtml extends SendMail{
    private ArrayList arrayList1 = new ArrayList();
    private ArrayList arrayList2 = new ArrayList();    public MailSendHtml(String smtpHost,String username,String password){
        super(smtpHost,username,password);
        multipart = new MimeMultipart("related");
    }    public void setMailContent(String mailContent)throws MessagingException{
        String htmlContent = getContent("<img src=",mailContent);
        System.out.println(htmlContent);//1
        messageBodyPart.setContent(htmlContent,"text/html");
        multipart.addBodyPart(messageBodyPart);
        //调用处理html文件中的图片方法
        processHtmlImage(mailContent);
    }
    //处理html页面上的图片方法如下：
    private void processHtmlImage(String mailContent)throws MessagingException{
         for(int i=0;i<arrayList1.size();i++){
             messageBodyPart = new MimeBodyPart();
             DataSource source = new FileDataSource((String)arrayList1.get(i));
             messageBodyPart.setDataHandler(new DataHandler(source));
             String contentId = "<"+(String)arrayList2.get(i)+">";
             System.out.println(contentId);
             messageBodyPart.setHeader("Content-ID",contentId);
             messageBodyPart.setFileName((String)arrayList1.get(i));
             multipart.addBodyPart(messageBodyPart);
         }
    }
    //处理要发送的html文件，主要是针对html文件中的图片
    private String getContent(String searchString,String mailContent){
        String afterReplaceStr = "";
        for(int i=0;i<mailContent.length();i++){
            for(int j=i+1;j<mailContent.length();j++){
                String searResult = mailContent.substring(i,j);
                if(searResult.equalsIgnoreCase(searchString)){
                    String subString = mailContent.substring(j);
                    int flagIndex = subString.indexOf('>');
                    String replaceStr = subString.substring(1,flagIndex-1);
                    if(replaceStr.indexOf("http://") != -1){
                        System.out.println(replaceStr);
                        System.out.println("不需要处理图片！");
                    }
                    else{                        arrayList1.add(replaceStr);
                    }
                }
            }
        }
        //在html文件中用"cid:"+Content-ID来替换原来的图片链接
        for(int m=0;m<arrayList1.size();m++){
            arrayList2.add(createRandomStr());
            String addString = "cid:"+(String)arrayList2.get(m);
            afterReplaceStr = mailContent.replaceAll((String)arrayList1.get(m),addString);
        }
        return afterReplaceStr;
    }
    //产生一个随机字符串，为了给图片设定Content-ID值
    private String createRandomStr(){
        char []randomChar = new char[8];
        for(int i=0;i<8;i++){
            randomChar[i]=(char)(Math.random()*26+'a');
        }
        String replaceStr = new String(randomChar);
        return replaceStr;
    }
}
测试代码
import java.util.Date;
public class SendMailTest{
    public void sendemail(String str){
        String []toAddress = {str};
        SendMail sendmail = new MailSendHtml("smtp.126.com","Cupid1945","yonghumima");
        try{
            sendmail.setSubject("赶快验证，你将享受超值服务");
            sendmail.setSendDate(new Date());
            //String plainText = "Welcome to use this Mail-Send program!";
            String htmlText =  "<strong><em></em>sadfsfsfsdfsdfsd</strong>";
           
                    
                  
            //sendmail.setMailContent(plainText);
            sendmail.setMailContent(htmlText);
            //sendmail.setAttachments("E:\\eclipse\\workspace\\cc\\eq1.htm");
            sendmail.setMailFrom("[email protected]","CNIC");
            sendmail.setMailTo(toAddress,"to");
            //sendmail.setMailTo(toAddress,"cc");
            sendmail.sendMail();
        }
        catch(Exception ex){ ex.printStackTrace();}
    }
    public static void main(String args[]){
        SendMailTest cc= new SendMailTest();
        cc.sendemail("[email protected]");
}
,理论上应该有HTML内容sadfsfsfsdfsdfsd的,结果YAHOO邮箱里除了标题,内容为空