import java.io.*;
import java.util.*;

public class Main {

    /**
     * csv格式订单下载，完成后伴随邮件通知下载
     * 步骤分三部，一步一步的看，其实很简单
     * 封装数据-->规范csv格式及写入文件-->邮件通知
     *
     * @author wappin
     */
    public static void main(String[] args) throws Exception {
        //封装数据
        //我这里随便写点测试数据，上项目的时候，这里换成数据库读的数据。
        List<Student> studentList = new ArrayList<>();
        studentList.add(new Student(1, "小明", "男", "18011111111"));
        studentList.add(new Student(2, "小王", "男", "18022222222"));
        studentList.add(new Student(3, "小张", "男", "18033333333"));
        studentList.add(new Student(4, "小红", "女", "18044444444"));
        studentList.add(new Student(5, "小花", "女", "18055555555"));

        //规范csv格式及写入文件
        File file = Configuring.configuringCsvFormat(studentList);

        //邮件通知
        SendEmailUtil.sendEmail("442042162@qq.com", file);

        //发送结束后删除文件，看个人需求使用
        //file.delete();
    }
    
}

/**
 *　学生实体类
 */
public class Student {
    private int id;            //id
    private String name;       //姓名
    private String gender;     //性别
    private String phoneNumber;//电话号码

    Student(int id, String name, String gender, String phoneNumber) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.phoneNumber = phoneNumber;
    }

    int getId() {
        return id;
    }

    String getName() {
        return name;
    }

    String getGender() {
        return gender;
    }

    String getPhoneNumber() {
        return phoneNumber;
    }

    void setId(int id) {
        this.id = id;
    }

    void setName(String name) {
        this.name = name;
    }

    void setGender(String gender) {
        this.gender = gender;
    }

    void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }
}

import java.io.*;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * 规范csv格式及写入文件
 * @author wappin
 */
public class Configuring {
    /**
     * 配置csv格式
     */
    static File configuringCsvFormat(List<Student> studentList) {
        LinkedHashMap<String, String> superClassMap = new LinkedHashMap<>();
        //key对应实体类参数，value对应csv标题
        superClassMap.put("id", "编号");
        superClassMap.put("name", "姓名");
        superClassMap.put("gender", "性别");
        superClassMap.put("phoneNumber", "电话号码");
        List<String> list = new ArrayList<>();
        StringBuilder sb = new StringBuilder();
        for (Student stu : studentList) {
            sb.append(stu.getId()).append("\t,").
                    append(stu.getName() != null ? stu.getName() : "").append("\t,").
                    append(stu.getGender() != null ? stu.getGender() : "").append("\t,").
                    append(stu.getPhoneNumber() != null ? stu.getPhoneNumber() : "").append("\t");
            list.add(sb.toString());
            sb.delete(0, sb.length());
        }
        return writeFile(list, superClassMap);
    }

    /**
     * 写入文件
     */
    private static <T> File writeFile(List<T> list, LinkedHashMap<String, String> fieldMap) {
        //文件存放地址及名称
        String downCsvForEmailAddress = "E:\\" + System.currentTimeMillis();
        File file = new File(downCsvForEmailAddress);
        FileOutputStream out;
        OutputStreamWriter osw = null;
        BufferedWriter bw = null;
        try {
            out = new FileOutputStream(file);
            osw = new OutputStreamWriter(out, "GBK");
            bw = new BufferedWriter(osw);
            if (fieldMap != null) {
                StringBuilder head = new StringBuilder();
                for (Map.Entry<String, String> stringStringEntry : fieldMap.entrySet()) {
                    head.append(",").append(((Map.Entry) stringStringEntry).getValue() != null ? (String) ((Map.Entry) stringStringEntry).getValue() : "");
                }
                head = new StringBuilder(head.substring(1, head.length()));
                bw.append(head.toString()).append("\r");
            }
            for (T aList : list) {
                bw.append(aList.toString()).append("\r");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (bw != null) {
                try {
                    bw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (osw != null) {
                try {
                    osw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return file;
    }
}

import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.BodyPart;
import javax.mail.Multipart;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.*;
import java.io.File;
import java.util.Date;
import java.util.Properties;

/**
 * JavaMail 版本: 1.6.0
 * JDK 版本: JDK 1.7 以上（必须）
 * 参考文档: http://blog.csdn.net/xietansheng/article/details/51673073
 */
public class SendEmailUtil {

    //发件人邮箱
    public static String myEmailAccount = "自己填";
    //授权码 > 独立密码 > 密码（优先级）
    public static String myEmailPassword = "自己填";
    //SMTP 服务器地址
    public static String myEmailSMTPHost = "smtp.qq.com";


    /**
     * 配置收件人及邮件协议信息
     *
     * @param receiveMailAccount 收件人地址
     * @param attachment         附件
     * @throws Exception
     */
    public static void sendEmail(String receiveMailAccount, File attachment) throws Exception {
        // 1. 创建参数配置, 用于连接邮件服务器的参数配置
        Properties props = new Properties();                    // 参数配置
        props.setProperty("mail.transport.protocol", "smtp");   // 使用的协议（JavaMail规范要求）
        props.setProperty("mail.smtp.host", myEmailSMTPHost);   // 发件人的邮箱的 SMTP 服务器地址
        props.setProperty("mail.smtp.auth", "true");            // 需要请求认证

        final String smtpPort = "465";
        props.setProperty("mail.smtp.port", smtpPort);
        props.setProperty("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
        props.setProperty("mail.smtp.socketFactory.fallback", "false");
        props.setProperty("mail.smtp.socketFactory.port", smtpPort);
        Session session = Session.getInstance(props);
        // 设置为debug模式, 可以查看详细的发送 log
        session.setDebug(false);

        // 3. 创建一封邮件
        MimeMessage message = createMimeMessage(session, myEmailAccount, receiveMailAccount, attachment);

        Transport transport = session.getTransport();
        transport.connect(myEmailAccount, myEmailPassword);
        transport.sendMessage(message, message.getAllRecipients());
        transport.close();
    }

    /**
     * 创建一封只包含文本的简单邮件
     *
     * @param session     和服务器交互的会话
     * @param sendMail    发件人邮箱
     * @param receiveMail 收件人邮箱
     * @param attachment  附件
     * @throws Exception
     */
    public static MimeMessage createMimeMessage(Session session, String sendMail, String receiveMail, File attachment) throws Exception {
        // 1. 创建一封邮件
        MimeMessage message = new MimeMessage(session);
        // 2. From: 发件人
        message.setFrom(new InternetAddress(sendMail, "", "UTF-8"));
        // 3. To: 收件人（可以增加多个收件人、抄送、密送）
        message.setRecipient(MimeMessage.RecipientType.TO, new InternetAddress(receiveMail, "收件人姓名", "UTF-8"));
        message.addHeader("charset", "UTF-8");
        message.setSubject("主题");

        //添加正文内容
        Multipart multipart = new MimeMultipart();
        BodyPart contentPart = new MimeBodyPart();
        contentPart.setContent("正文内容", "text/html;charset=UTF-8");
        multipart.addBodyPart(contentPart);
        //附件
        if (attachment != null) {
            BodyPart attachmentBodyPart = new MimeBodyPart();
            DataSource source = new FileDataSource(attachment);
            attachmentBodyPart.setDataHandler(new DataHandler(source));
            attachmentBodyPart.setFileName(MimeUtility.encodeText("附件名称.csv"));
            multipart.addBodyPart(attachmentBodyPart);
        }

        message.setContent(multipart);
        message.setSentDate(new Date());
        message.saveChanges();
        return message;
    }
}