用Java发送邮件，首先要获取授权码，这里使用qq邮箱发送邮件给自己，所以要获取qq邮箱的授权码。
    首先添加maven依赖,

    1. <dependency>
    2.  <groupId>javax.mail</groupId>
    3.  <artifactId>mail</artifactId>
    4.  <version>1.4</version>
    5. </dependency>

    代码写法基本是固定的。

    1. import java.security.Security;
    2. import java.util.Properties;
    3. import javax.mail.Authenticator;
    4. import javax.mail.Message;
    5. import javax.mail.PasswordAuthentication;
    6. import javax.mail.Session;
    7. import javax.mail.Transport;
    8. import javax.mail.internet.InternetAddress;
    9. import javax.mail.internet.MimeMessage;
    10. import com.sun.net.ssl.internal.ssl.Provider;
    12. public class MailClient{
    13.     public static void main(String[] args){
    14.         try{
    15.             //设置SSL连接、邮件环境
    16.             Security.addProvider(new Provider());
    17.             final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";
    19.             //配置邮箱信息
    20.             Properties props = System.getProperties();
    21.             //邮件服务器
    22.             props.setProperty("mail.smtp.host","smtp.qq.com");
    23.             props.setProperty("mail.smtp.socketFactory.class",SSL_FACTORY);
    24.             props.setProperty("mail.smtp.socketFactory.fallback","false");
    25.             //邮件服务器端口
    26.             props.setProperty("mail.smtp.port","465");
    27.             props.setProperty("mail.smtp.socketFactory.port","465");
    28.             //鉴权信息
    29.             props.setProperty("mail.smtp.auth","true");
    30.             //建立邮件会话
    31.             Session session = Session.getDefaultInstance(props,new Authenticator(){
    32.                 //身份认证
    33.                 protected PasswordAuthentication getPasswordAuthentication(){
    34.                     //账户 授权码
    35.                     return new PasswordAuthentication("xxx@qq.com","xxxx");
    36.                 }
    37.             });
    38.             //建立邮件对象
    39.             MimeMessage message = new MimeMessage(session);
    40.             //设置邮件的发件人
    41.             message.setFrom(new InternetAddress("xxxx@qq.com"));
    42.             //设置邮件的收件人,可设置多个收件人用逗号隔开
    43.             message.setRecipients(Message.RecipientType.TO,"xxxx@qq.com,xxx@163.com");
    44.             //设置邮件的主题
    45.             message.setSubject("通过javamail发出");
    46.             //文本内容
    47.             message.setContent("文本邮件测试","text/html;charset=UTF-8");
    48.             message.saveChanges();
    49.             //发送邮件
    50.             Transport.send(message);
    52.         }catch(Exception e){
    53.             e.printStackTrace();
    54.         }
    55.     }
    56. }

    下面的代码复用性更好

    1. package com.youkeda.test.j3.c9;
    3. import com.sun.net.ssl.internal.ssl.Provider;
    4. import java.security.Security;
    5. import java.util.Properties;
    6. import javax.mail.Authenticator;
    7. import javax.mail.Message;
    8. import javax.mail.PasswordAuthentication;
    9. import javax.mail.Session;
    10. import javax.mail.Transport;
    11. import javax.mail.internet.InternetAddress;
    12. import javax.mail.internet.MimeMessage;
    14. public class Mail {
    16.   private static final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";
    17.   private static Properties props = null;
    19.   // TODO:发件人信箱
    20.   private static final String FROM_MAIL = "xxxx@qq.com";
    21.   // TODO:发件人信箱安全key即授权码
    22.   private static final String FROM_MAIL_KEY = "";
    23.   // TODO:收件人信箱 可多个
    24.   private static final String TO_MAIL = "xxx@163.com";
    26.   /**
    27.    * 在构造函数中初始化相关的参数。这是固定用法。
    28.    */
    29.   public Mail() {
    30.     // 设置SSL连接、邮件环境
    31.     Security.addProvider(new Provider());
    32.     props = System.getProperties();
    33.     props.setProperty("mail.smtp.host", "smtp.qq.com");
    34.     props.setProperty("mail.smtp.socketFactory.class", SSL_FACTORY);
    35.     props.setProperty("mail.smtp.socketFactory.fallback", "false");
    36.     props.setProperty("mail.smtp.port", "465");
    37.     props.setProperty("mail.smtp.socketFactory.port", "465");
    38.     props.setProperty("mail.smtp.auth", "true");
    39.   }
    41.   /**
    42.    * 发送邮件
    43.    * @param subject
    44.    * @param content
    45.    */
    46.   public void sendMail(String subject, String content) {
    47.     try {
    48.       // 建立邮件会话
    49.       Session session = Session.getDefaultInstance(props, new Authenticator() {
    50.         // 身份认证
    51.         protected PasswordAuthentication getPasswordAuthentication() {
    52.           // 账户 授权码
    53.           return new PasswordAuthentication(FROM_MAIL, FROM_MAIL_KEY);
    54.         }
    55.       });
    57.       // 建立邮件对象
    58.       MimeMessage message = new MimeMessage(session);
    59.       // 设置邮件的发件人、收件人、主题
    60.       // 附带发件人名字
    61.       message.setFrom(new InternetAddress(FROM_MAIL));
    62.       message.setRecipients(Message.RecipientType.TO, TO_MAIL);
    63.       message.setSubject(subject);
    64.       // 文本部分
    65.       message.setContent(content, "text/html;charset=UTF-8");
    66.       message.saveChanges();
    67.       // 发送邮件
    68.       Transport.send(message);
    69.     } catch (Exception e) {
    70.       e.printStackTrace();
    71.     }
    72.   }
    73. }