java发送邮件无法显示图片 图裂 的解决办法

package com.thinkgem.jeesite.common.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Date;
import java.util.Enumeration;
import java.util.Properties;
import java.util.Vector;   

import javax.activation.*;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.internet.MimeUtility;   

/**
 * <p>
 * Title: 使用javamail发送邮件
 * </p>
 */
public class MailUtils {

    private static Logger logger = LoggerFactory.getLogger(MailUtils.class);

    String to = "";// 收件人
    String toCC = "";//抄送
    String toBcc = "";//密送
    String from = "";// 发件人
    String host = "";// smtp主机
    String port = "";
    String username = "";
    String password = "";
    String filename = "";// 附件文件名
    String subject = "";// 邮件主题
    String content = "";// 邮件正文
    String imagepath = "";// 图片路径
    Vector file = new Vector();// 附件文件集合

    public String getImagepath() {
        return imagepath;
    }

    public void setImagepath(String imagepath) {
        this.imagepath = imagepath;
    }

    /**
     * <br>
     * 方法说明：默认构造器 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public MailUtils() {
    }   

    /**
     * <br>
     * 方法说明：构造器，提供直接的参数传入 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public MailUtils(String to, String from, String smtpServer,
            String username, String password, String subject, String content) {
        this.to = to;
        this.from = from;
        this.host = smtpServer;
        this.username = username;
        this.password = password;
        this.subject = subject;
        this.content = content;
    }   

    public void setPort(String port){
        this.port = port;
    }

    /**
     * <br>
     * 方法说明：设置邮件服务器地址 <br>
     * 输入参数：String host 邮件服务器地址名称 <br>
     * 返回类型：
     */
    public void setHost(String host) {
        this.host = host;
    }   

    /**
     * <br>
     * 方法说明：设置登录服务器校验密码 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public void setPassWord(String pwd) {
        this.password = pwd;
    }   

    /**
     * <br>
     * 方法说明：设置登录服务器校验用户 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public void setUserName(String usn) {
        this.username = usn;
    }   

    /**
     * <br>
     * 方法说明：设置邮件发送目的邮箱 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public void setTo(String to) {
        this.to = to;
    }   

    /**
     * 设置抄送者
     *
     * */
    public void setToCC(String to){
        this.toCC = to;
    }

    public void setToBcc(String to){
        this.toBcc = to;
    }

    /**
     * <br>
     * 方法说明：设置邮件发送源邮箱 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public void setFrom(String from) {
        this.from = from;
    }   

    /**
     * <br>
     * 方法说明：设置邮件主题 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public void setSubject(String subject) {
        this.subject = subject;
    }   

    /**
     * <br>
     * 方法说明：设置邮件内容 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public void setContent(String content) {
        this.content = content;
    }   

    /**
     * <br>
     * 方法说明：把主题转换为中文 <br>
     * 输入参数：String strText <br>
     * 返回类型：
     */
    public String transferChinese(String strText) {
        try {
            strText = MimeUtility.encodeText(new String(strText.getBytes("UTF-8"),
                    "UTF-8"), "UTF-8", "B");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return strText;
    }   

    /**
     * <br>
     * 方法说明：往附件组合中添加附件 <br>
     * 输入参数： <br>
     * 返回类型：
     */
    public void attachfile(String fname) {
        file.addElement(fname);
    }   

    /**
     * <br>
     * 方法说明：发送邮件 <br>
     * 输入参数： <br>
     * 返回类型：boolean 成功为true，反之为false
     */
    public boolean sendMail() {
        logger.info("------开始发邮件------");
        // 构造mail session
        Properties props = new Properties() ;
        props.put("mail.smtp.host", host);
        props.put("mail.smtp.auth", "true");
        if(port != "")
            props.put("mail.smtp.port", port);
        Session session = Session.getDefaultInstance(props,
                new Authenticator() {
                    public PasswordAuthentication getPasswordAuthentication() {
                        return new PasswordAuthentication(username, password);
                    }
                });
        //Session session = Session.getDefaultInstance(props);
//      Session session = Session.getDefaultInstance(props, null);   

        try {
            // 构造MimeMessage 并设定基本的值
            MimeMessage msg = new MimeMessage(session);
            //MimeMessage msg = new MimeMessage();
            msg.setFrom(new InternetAddress(from));   

            //msg.addRecipients(Message.RecipientType.TO, address); //这个只能是给一个人发送email
            //设置接收者
            if(!Empty2String(to))
                msg.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to)) ;
            //设置抄送者
            if(!Empty2String(toCC))
                msg.setRecipients(Message.RecipientType.CC, InternetAddress.parse(toCC)) ;
            //设置密送者
            if(!Empty2String(toBcc))
                msg.setRecipients(Message.RecipientType.BCC, InternetAddress.parse(toBcc)) ;

            subject = transferChinese(subject);
            msg.setSubject(subject);   

            // 构造Multipart
            Multipart mp = new MimeMultipart();   

            // 向Multipart添加正文
            MimeBodyPart mbpContent = new MimeBodyPart();
            mbpContent.setContent(content, "text/html;charset=gb2312");   

            // 向MimeMessage添加（Multipart代表正文）
            mp.addBodyPart(mbpContent);   

            // 向Multipart添加附件
            Enumeration efile = file.elements();
            while (efile.hasMoreElements()) {   

                MimeBodyPart mbpFile = new MimeBodyPart();
                filename = efile.nextElement().toString();
                FileDataSource fds = new FileDataSource(filename);
                mbpFile.setDataHandler(new DataHandler(fds));
               //<SPAN style="COLOR: #ff0000">//这个方法可以解决附件乱码问题。</SPAN>
                String filename= new String(fds.getName().getBytes(),"ISO-8859-1");   

                mbpFile.setFileName(filename);
                // 向MimeMessage添加（Multipart代表附件）
                mp.addBodyPart(mbpFile);   

            }   

            file.removeAllElements();
            // 向Multipart添加MimeMessage
            msg.setContent(mp);
            msg.setSentDate(new Date());
            msg.saveChanges() ;
            // 发送邮件   

            Transport transport = session.getTransport("smtp");
            transport.connect(host, username, password);
            transport.sendMessage(msg, msg.getAllRecipients());
            transport.close();
        } catch (Exception mex) {
            mex.printStackTrace();
            logger.info("---发邮件报错信息----"+mex.getMessage());
//          Exception ex = null;
//          if ((ex = mex.getNextException()) != null) {
//              ex.printStackTrace();
//          }
            return false;
        }
        return true;
    }

    /***
     * 发送带有图片的邮件
     * @return
     */
    public boolean sendPicMail() {
        logger.info("------开始发邮件------");
        // 构造mail session
        Properties props = new Properties() ;
        props.put("mail.smtp.host", host);
        props.put("mail.smtp.auth", "true");
        if(port != "")
            props.put("mail.smtp.port", port);
        Session session = Session.getDefaultInstance(props,
                new Authenticator() {
                    public PasswordAuthentication getPasswordAuthentication() {
                        return new PasswordAuthentication(username, password);
                    }
                });
        //Session session = Session.getDefaultInstance(props);
//      Session session = Session.getDefaultInstance(props, null);

        try {
            // 构造MimeMessage 并设定基本的值
            MimeMessage msg = new MimeMessage(session);
            //MimeMessage msg = new MimeMessage();
            msg.setFrom(new InternetAddress(from));

            //msg.addRecipients(Message.RecipientType.TO, address); //这个只能是给一个人发送email
            //设置接收者
            if(!Empty2String(to))
                msg.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to)) ;
            //设置抄送者
            if(!Empty2String(toCC))
                msg.setRecipients(Message.RecipientType.CC, InternetAddress.parse(toCC)) ;
            //设置密送者
            if(!Empty2String(toBcc))
                msg.setRecipients(Message.RecipientType.BCC, InternetAddress.parse(toBcc)) ;

            subject = transferChinese(subject);
            msg.setSubject(subject);

            // 构造Multipart
            MimeMultipart mp = new MimeMultipart("related");

            // 向Multipart添加正文
            MimeBodyPart mbpContent = new MimeBodyPart();
            mbpContent.setContent(content, "text/html;charset=gb2312");

            // 向MimeMessage添加（Multipart代表正文）
            mp.addBodyPart(mbpContent);

            // second part (the image)
            MimeBodyPart imageBodyPart = new MimeBodyPart();
            DataSource imageds = new FileDataSource(imagepath);
            imageBodyPart.setDataHandler(new DataHandler(imageds));
            imageBodyPart.setHeader("Content-ID","<attach>");
            imageBodyPart.setHeader("Content-Type", "image/png");
            imageBodyPart.setDisposition(MimeBodyPart.INLINE);
            imageBodyPart.setFileName("attach.png");

            // add it
            mp.addBodyPart(imageBodyPart);

            // 向Multipart添加附件
            Enumeration efile = file.elements();
            while (efile.hasMoreElements()) {

                MimeBodyPart mbpFile = new MimeBodyPart();
                filename = efile.nextElement().toString();
                FileDataSource fds = new FileDataSource(filename);
                mbpFile.setDataHandler(new DataHandler(fds));
                //<SPAN style="COLOR: #ff0000">//这个方法可以解决附件乱码问题。</SPAN>
                String filename= new String(fds.getName().getBytes(),"ISO-8859-1");

                mbpFile.setFileName(filename);
                // 向MimeMessage添加（Multipart代表附件）
                mp.addBodyPart(mbpFile);

            }

            file.removeAllElements();
            // 向Multipart添加MimeMessage
            msg.setContent(mp);
            msg.setSentDate(new Date());
            msg.saveChanges() ;
            // 发送邮件

            Transport transport = session.getTransport("smtp");
            transport.connect(host, username, password);
            transport.sendMessage(msg, msg.getAllRecipients());
            transport.close();
        } catch (Exception mex) {
            mex.printStackTrace();
            logger.info("---发邮件报错信息----"+mex.getMessage());
//          Exception ex = null;
//          if ((ex = mex.getNextException()) != null) {
//              ex.printStackTrace();
//          }
            return false;
        }
        return true;
    }

    public static boolean Empty2String(String str){
        return str == null || "".equals(str) || "null".equals(str) || "NULL".equals(str);
    }

    /**
     * <br>
     * 方法说明：主方法，用于测试 <br>
     * 输入参数： <br>
     * 返回类型：
     */  

    public static void main(String[] args) {
        MailUtils sendmail = new MailUtils();  

        sendmail.setHost("smtp.cmge.com");
        sendmail.setUserName("[e-mail]");
        sendmail.setFrom("[e-mail]");
        sendmail.setPassWord("XXXXX");

        sendmail.setTo("[e-mail],[e-mail]");
        //sendmail.setToCC("");

        sendmail.setSubject("你好22，这是测ddddd试！");
        sendmail.setContent("<h1>你好这是一个带多附件多人发送的的测试！~~~~~~~~~~~~~~~~~~~~~~~~~</h1>"+"<img src=\"cid:attach\">");   

　　　　 sendmail.setImagepath(picpath);

        sendmail.sendPicMail()
        //sendmail.attachfile("F:\\mac共享\\受害用户名单20150119.csv");
        //sendmail.attachfile("F:\\mac共享\\接听转接验证号码20150119.csv");
       // logger.info(sendmail.sendMail());
    }
}

防止图裂：

要想正确显示邮件的图片内容，必须做到如下几点：
1. MimeMultipart的类型必须是“related”（new MimeMultipart(“related”)）；
2. 图片的显示方式必须为“INLINE”（Disposition=MimeBodyPart.INLINE）；
3. 必须明确指定“Content-Type”头信息（Content-Type=image/png）；
4. 图片名称与“Content-ID”绝不能为“image”（可能为关键字）；

参考帖子：

https://blog.csdn.net/yiifaa/article/details/78394230