java中javamail发送带附件的邮件实现方法

package mail;  
  
import java.util.* ;  
import java.io.* ;  
import javax.mail.* ;  
import javax.mail.internet.* ;  
import javax.activation.* ;  
public class Mail {  
    //定义发件人、收件人、SMTP服务器、用户名、密码、主题、内容等  
    private String displayName;  
    private String to;  
    private String from;  
    private String smtpServer;  
    private String username;  
    private String password;  
    private String subject;  
    private String content;  
    private boolean ifAuth; //服务器是否要身份认证  
    private String filename="";  
    private Vector file = new Vector(); //用于保存发送附件的文件名的集合
     
    /** 
     * 设置SMTP服务器地址 
     */  
    public void setSmtpServer(String smtpServer){  
        this.smtpServer=smtpServer;  
    }  
     
    /** 
     * 设置发件人的地址 
     */  
    public void setFrom(String from){  
        this.from=from;  
    }  
    /** 
     * 设置显示的名称 
     */  
    public void setDisplayName(String displayName){  
        this.displayName=displayName;  
    }  
     
    /** 
     * 设置服务器是否需要身份认证 
     */  
    public void setIfAuth(boolean ifAuth){  
        this.ifAuth=ifAuth;  
    }  
     
    /** 
     * 设置E-mail用户名 
     */  
    public void setUserName(String username){  
        this.username=username;  
    }  
     
    /** 
     * 设置E-mail密码 
     */  
    public void setPassword(String password){  
        this.password=password;  
    }  
     
    /** 
     * 设置接收者 
     */  
    public void setTo(String to){  
        this.to=to;  
    }  
     
    /** 
     * 设置主题 
     */  
    public void setSubject(String subject){  
        this.subject=subject;  
    }  
     
    /** 
     * 设置主体内容 
     */  
    public void setContent(String content){  
        this.content=content;  
    }  
     
    /** 
     * 该方法用于收集附件名 
     */  
    public void addAttachfile(String fname){  
        file.addElement(fname);  
    }  
     
    public Mail(){  
         
    }  
     
    /** 
     * 初始化SMTP服务器地址、发送者E-mail地址、用户名、密码、接收者、主题、内容 
     */  
    public Mail(String smtpServer,String from,String displayName,String username,String password,String to,String subject,String content){  
        this.smtpServer=smtpServer;  
        this.from=from;  
        this.displayName=displayName;  
        this.ifAuth=true;  
        this.username=username;  
        this.password=password;  
        this.to=to;  
        this.subject=subject;  
        this.content=content;  
    }  
     
    /** 
     * 初始化SMTP服务器地址、发送者E-mail地址、接收者、主题、内容 
     */  
    public Mail(String smtpServer,String from,String displayName,String to,String subject,String content){  
        this.smtpServer=smtpServer;  
        this.from=from;  
        this.displayName=displayName;  
        this.ifAuth=false;  
        this.to=to;  
        this.subject=subject;  
        this.content=content;  
    }  
  
    /** 
     * 发送邮件 
     */  
    public HashMap send(){  
        HashMap map=new HashMap();  
        map.put("state", "success");  
        String message="邮件发送成功！";  
        Session session=null;  
        Properties props = System.getProperties();  
        props.put("mail.smtp.host", smtpServer);  
        if(ifAuth){ //服务器需要身份认证  
            props.put("mail.smtp.auth","true");     
            SmtpAuth smtpAuth=new SmtpAuth(username,password);  
            session=Session.getDefaultInstance(props, smtpAuth);   
        }else{  
            props.put("mail.smtp.auth","false");  
            session=Session.getDefaultInstance(props, null);  
        }  
        session.setDebug(true);  
        Transport trans = null;    
        try {  
            Message msg = new MimeMessage(session);   
            try{  
                Address from_address = new InternetAddress(from, displayName);  
                msg.setFrom(from_address);  
            }catch(java.io.UnsupportedEncodingException e){  
                e.printStackTrace();  
            }  
            InternetAddress[] address={new InternetAddress(to)};  
            msg.setRecipients(Message.RecipientType.TO,address);  
            msg.setSubject(subject);  
            Multipart mp = new MimeMultipart();  
            MimeBodyPart mbp = new MimeBodyPart();  
            mbp.setContent(content.toString(), "text/html;charset=gb2312");  
            mp.addBodyPart(mbp);    
            if(!file.isEmpty()){//有附件  
                Enumeration efile=file.elements();  
                while(efile.hasMoreElements()){   
                    mbp=new MimeBodyPart();  
                    filename=efile.nextElement().toString(); //选择出每一个附件名  
                    FileDataSource fds=new FileDataSource(filename); //得到数据源  
                    mbp.setDataHandler(new DataHandler(fds)); //得到附件本身并至入BodyPart  
                    mbp.setFileName(fds.getName());  //得到文件名同样至入BodyPart  
                    mp.addBodyPart(mbp);  
                }    
                file.removeAllElements();      
            }   
            msg.setContent(mp); //Multipart加入到信件  
            msg.setSentDate(new Date());     //设置信件头的发送日期  
            //发送信件  
            msg.saveChanges();   
            trans = session.getTransport("smtp");  
            trans.connect(smtpServer, username, password);  
            trans.sendMessage(msg, msg.getAllRecipients());  
            trans.close();  
             
        }catch(AuthenticationFailedException e){     
             map.put("state", "failed");  
             message="邮件发送失败！错误原因：\n"+"身份验证错误!";  
             e.printStackTrace();   
        }catch (MessagingException e) {  
             message="邮件发送失败！错误原因：\n"+e.getMessage();  
             map.put("state", "failed");  
             e.printStackTrace();  
             Exception ex = null;  
             if ((ex = e.getNextException()) != null) {  
                 System.out.println(ex.toString());  
                 ex.printStackTrace();  
             }   
        }  
        //System.out.println("\n提示信息:"+message);  
        map.put("message", message);  
        return map;  
    }  
}

package mail;  
  
public class SmtpAuth extends javax.mail.Authenticator {   
    private String username,password;   
  
    public SmtpAuth(String username,String password){   
        this.username = username;    
        this.password = password;    
    }   
    protected javax.mail.PasswordAuthentication getPasswordAuthentication() {   
        return new javax.mail.PasswordAuthentication(username,password);
    }   
}