Java Email 发HTML邮件工具 采用 freemarker模板引擎渲染

Java Email 发HTML邮件工具 采用 freemarker模板引擎

1.常用方式对比

Java发送邮件有很多的实现方式

• 第一种：Java 原生发邮件mail.jar和activation.jar

  <!-- https://mvnrepository.com/artifact/javax.mail/mail -->
  <dependency><groupId>javax.mail</groupId><artifactId>mail</artifactId><version>1.4.7</version>
  </dependency>
  <!-- https://mvnrepository.com/artifact/javax.activation/activation -->
  <dependency><groupId>javax.activation</groupId><artifactId>activation</artifactId><version>1.1.1</version>
  </dependency>
  

  原生的java可以发送普通文本和HTML邮件，同时也可以发送带附件的邮件，但是缺点也很明显，配置非常繁琐，不同的邮件需要不同的实现类去完成，不适合项目中使用。

• 第二种：使用框架提供的去实现，在SpringBoot中有实现这个功能的组件spring-boot-starter-mail

  <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-mail -->
  <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-mail</artifactId>
  </dependency>
  

  这种实现起来特别方便，仅仅只要在SpringBoot项目中引入组件，在配置文件中配置好各种参数，就可以实现依赖注入，调用接口完成发送邮件，同时支持普通文本、HTML邮件、以及携带附件的邮件。同时缺点就是和框架集成太高了，如果项目中没有使用SpringBoot就不是那么好用了。

• 第三种：采用Apache提供的邮件工具commons-email,项目中已经封装好了一些常用的发邮件的接口供开发者使用，并且配置起来也比较简单，和其他技术耦合低是比较好的解决问题的方案。

  <dependency><groupId>org.apache.commons</groupId><artifactId>commons-email</artifactId><version>1.5</version>
  </dependency>
  

2.项目中使用

项目使用的jar包，采用maven工程。

<dependency><groupId>org.apache.commons</groupId><artifactId>commons-email</artifactId><version>1.5</version>
</dependency>

第三方jar包引入时下载：https://mvnrepository.com/artifact/org.apache.commons/commons-email

（1）创建配置文件email.properties

• 建议将配置文件统一放置在resources文件夹中

# 邮件服务器的地址
host=smtp.exmail.qq.com
# 邮件服务器的端口（百度上有，或者邮件提供商开发文档有）
port=456
# 发件人邮箱
username=
# 密码或授权码
password=
# 发件人名称，如果不提供会使用发件人邮件作为发件人
formName=

（2）发邮件的核心代码

package com.zhongcode.demo.email;import org.apache.commons.mail.*;import java.util.Collections;
import java.util.List;
import java.util.Properties;/*** 邮件发送实例*/
public class SendEmail {/*** 邮件服务器 host*/private String host;/*** 邮件服务器端口 port*/private int port;/*** 用户名*/private String username;/*** 密码（授权码）*/private String password;/*** 发件人名称*/private String formName;/*** 是否开启debug*/private boolean debug;public SendEmail() {}public SendEmail(Properties pro) {this.host = pro.getProperty("host");this.port = Integer.parseInt(pro.getProperty("port", "0"));this.username = pro.getProperty("username");this.password = pro.getProperty("password");this.formName = pro.getProperty("formName");}public SendEmail(String host, int port, String username, String password, String formName, boolean debug) {this.host = host;this.port = port;this.username = username;this.password = password;this.formName = formName;this.debug = debug;}public SendEmail(String host, int port, String username, String password, String formName) {this.host = host;this.port = port;this.username = username;this.password = password;this.formName = formName;}public SendEmail(String host, int port, String username, String password) {this.host = host;this.port = port;this.username = username;this.password = password;}public String getHost() {return host;}public void setHost(String host) {this.host = host;}public int getPort() {return port;}public void setPort(int port) {this.port = port;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getFormName() {return formName;}public void setFormName(String formName) {this.formName = formName;}public boolean isDebug() {return debug;}public void setDebug(boolean debug) {this.debug = debug;}/*** 发邮件** @param to      收件件人* @param subject 主题* @param msg     消息* @throws EmailException 邮件异常*/public synchronized void sendEmail(String to, String subject, String msg) throws EmailException {sendEmail(Collections.singletonList(to), subject, msg, null, null);}/*** 发邮件** @param toEmails 发送列表* @param subject  主题* @param msg      内容支持html* @param attaches 附件* @param fromName 发送名称* @throws EmailException 邮件异常*/public synchronized void sendEmail(List<String> toEmails, String subject, String msg, List<String> attaches, String fromName) throws EmailException {// 创建邮件对象MultiPartEmail email;// 当附件不为空时，使用MultiPartEmail添加附件if (attaches != null) {email = new MultiPartEmail();for (String att : attaches) {EmailAttachment attachment = new EmailAttachment();attachment.setPath(att);// 截取文件名attachment.setName(att.substring(att.lastIndexOf("/") + 1));email.attach(attachment);}// 当使用MultiPartEmail时渲染html要使用Part进行添加email.addPart(msg, "text/html; charset=UTF-8");} else {// 默认使用HtmlEmail创建email = new HtmlEmail();email.setMsg(msg);}// 设置主机email.setHostName(host);// 设置端口email.setSmtpPort(port);email.setDebug(debug);email.setAuthenticator(new DefaultAuthenticator(username, password));email.setCharset("UTF-8");email.setSSLOnConnect(true);email.setFrom(username, fromName == null ? (this.formName == null ? username : this.formName) : fromName);email.setSubject(subject);for (String to : toEmails) {email.addTo(to);}email.send();}
}

（3）程序发邮件测试

public static void main(String[] args) throws EmailException, IOException, TemplateException {// 加载配置文件InputStream is = Main.class.getClassLoader().getResourceAsStream("email.properties");Properties pro = new Properties();pro.load(is);// 创建邮件SendEmail sendEmail = new SendEmail(pro);sendEmail.sendEmail("收件人", "test", "测试邮件");
}

3.发送HTML模板邮件

当我们想发送模板HTML时，需要发送HTML格式的代码，主要是纯文本的邮件并不好看，而且项目中经常使用的是好看的模板，比如系统用户注册时需要发送验证码，很多情况下都要发邮件。

这里我们采用的freemarker模板引擎来渲染我们的HTML模板，下面是以发送邮箱验证码为例。

（1）引入freemarker模板引擎

<dependency><groupId>org.freemarker</groupId><artifactId>freemarker</artifactId><version>2.3.32</version>
</dependency>

（2）创建HTML模板

文件名：code.ftl

<meta charset="utf-8"><table width="100%"><tr><td style="width: 100%;"><center><table class="content-wrap" style="margin: 0px auto; width: 600px;"><tr><td style="margin: 0px auto; overflow: hidden; padding: 0px; border: 0px dotted rgb(238, 238, 238);"><!----><div class="full" tindex="1" style="margin: 0px auto; max-width: 600px;"><table align="center" border="0" cellpadding="0" cellspacing="0" class="fullTable" style="width: 600px;"><tbody><tr><td class="fullTd" style="direction: ltr; width: 600px; font-size: 0px; padding-bottom: 0px; text-align: center; vertical-align: top; background-color: rgb(170, 0, 170); background-image: url(&quot;&quot;); background-repeat: no-repeat; background-size: 100px; background-position: 10% 50%;"><table border="0" cellpadding="0" cellspacing="0" width="100%" style="vertical-align: top;"><tr><td align="left" style="font-size: 0px; padding: 20px;"><div class="text" style="font-family: 微软雅黑, &quot;Microsoft YaHei&quot;; overflow-wrap: break-word; margin: 0px; text-align: center; line-height: 1.6; color: rgb(255, 255, 255); font-size: 18px; font-weight: normal;"><div><p style="text-size-adjust: none; word-break: break-word; line-height: 1.6; font-size: 18px; margin: 0px;"><strong>系统提示</strong></p></div></div></td></tr></table></td></tr></tbody></table></div><div class="full" tindex="2" style="margin: 0px auto; max-width: 600px;"><table align="center" border="0" cellpadding="0" cellspacing="0" class="fullTable" style="width: 600px;"><tbody><tr><td class="fullTd" style="direction: ltr; width: 600px; font-size: 0px; padding-bottom: 0px; text-align: center; vertical-align: top; background-image: url(&quot;&quot;); background-repeat: no-repeat; background-size: 100px; background-position: 10% 50%;"><table border="0" cellpadding="0" cellspacing="0" width="100%" style="vertical-align: top;"><tr><td align="left" style="font-size: 0px; padding: 20px 20px 5px;"><div class="text" style="font-family: 微软雅黑, &quot;Microsoft YaHei&quot;; overflow-wrap: break-word; margin: 0px; text-align: left; line-height: 20px; color: rgb(102, 102, 102); font-size: 14px; font-weight: normal;"><div><p style="text-size-adjust: none; word-break: break-word; line-height: 20px; font-size: 14px; margin: 0px;">您的验证码为：</p></div></div></td></tr></table></td></tr></tbody></table></div><div class="full" tindex="3" style="margin: 0px auto; max-width: 600px;"><table align="center" border="0" cellpadding="0" cellspacing="0" class="fullTable" style="width: 600px;"><tbody><tr><td class="fullTd" style="direction: ltr; width: 600px; font-size: 0px; padding-bottom: 0px; text-align: center; vertical-align: top; background-image: url(&quot;&quot;); background-repeat: no-repeat; background-size: 100px; background-position: 10% 50%;"><table border="0" cellpadding="0" cellspacing="0" width="100%" style="vertical-align: top;"><tr><td align="left" style="font-size: 0px; padding: 20px;"><div class="text" style="font-family: 微软雅黑, &quot;Microsoft YaHei&quot;; overflow-wrap: break-word; margin: 0px; text-align: center; line-height: 20px; color: rgb(0, 0, 0); font-size: 24px; font-weight: normal;"><div><p style="text-size-adjust: none; word-break: break-word; line-height: 20px; font-size: 24px; margin: 0px;"><strong>${code}</strong></p></div></div></td></tr></table></td></tr></tbody></table></div><div class="full" tindex="4" style="margin: 0px auto; max-width: 600px;"><table align="center" border="0" cellpadding="0" cellspacing="0" class="fullTable" style="width: 600px;"><tbody><tr><td class="fullTd" style="direction: ltr; width: 600px; font-size: 0px; padding-bottom: 0px; text-align: center; vertical-align: top; background-image: url(&quot;&quot;); background-repeat: no-repeat; background-size: 100px; background-position: 10% 50%;"><table border="0" cellpadding="0" cellspacing="0" width="100%" style="vertical-align: top;"><tr><td align="left" style="font-size: 0px; padding: 8px 20px 20px;"><div class="text" style="font-family: 微软雅黑, &quot;Microsoft YaHei&quot;; overflow-wrap: break-word; margin: 0px; text-align: left; line-height: 20px; color: rgb(102, 102, 102); font-size: 12px; font-weight: normal;"><div><p style="text-size-adjust: none; word-break: break-word; line-height: 20px; font-size: 12px; margin: 0px;"><span style="color: #333333;">验证码10分钟内有效。</span></p></div></div></td></tr></table></td></tr></tbody></table></div><div class="full" tindex="5" style="margin: 0px auto; line-height: 0px; max-width: 600px;"><table align="center" border="0" cellpadding="0" cellspacing="0" class="fullTable" style="width: 600px;"><tbody><tr><td align="center" class="fullTd" style="direction: ltr; font-size: 0px; padding: 10px 20px; text-align: center; vertical-align: top; word-break: break-word; width: 600px; background-image: url(&quot;&quot;); background-repeat: no-repeat; background-size: 100px; background-position: 10% 50%;"><table align="center" border="0" cellpadding="0" cellspacing="0" style="border-collapse: collapse; border-spacing: 0px;"><tbody><tr><td style="width: 600px; border-top: 1px solid rgb(204, 204, 204);"></td></tr></tbody></table></td></tr></tbody></table></div><div class="full" tindex="6" style="margin: 0px auto; max-width: 600px;"><table align="center" border="0" cellpadding="0" cellspacing="0" class="fullTable" style="width: 600px;"><tbody><tr><td class="fullTd" style="direction: ltr; width: 600px; font-size: 0px; padding-bottom: 0px; text-align: center; vertical-align: top; background-image: url(&quot;&quot;); background-repeat: no-repeat; background-size: 100px; background-position: 10% 50%;"><table border="0" cellpadding="0" cellspacing="0" width="100%" style="vertical-align: top;"><tr><td align="left" style="font-size: 0px; padding: 10px 20px 0px;"><div class="text" style="font-family: 微软雅黑, &quot;Microsoft YaHei&quot;; overflow-wrap: break-word; margin: 0px; text-align: left; line-height: 20px; color: rgb(170, 170, 170); font-size: 12px; font-weight: normal;"><div><p style="text-size-adjust: none; word-break: break-word; line-height: 20px; font-size: 12px; margin: 0px;">此为系统邮件请勿回复</p></div></div></td></tr></table></td></tr></tbody></table></div><div class="full" tindex="7" style="margin: 0px auto; max-width: 600px;"><table align="center" border="0" cellpadding="0" cellspacing="0" class="fullTable" style="width: 600px;"><tbody><tr><td class="fullTd" style="direction: ltr; width: 600px; font-size: 0px; padding-bottom: 0px; text-align: center; vertical-align: top; background-image: url(&quot;&quot;); background-repeat: no-repeat; background-size: 100px; background-position: 10% 50%;"><table border="0" cellpadding="0" cellspacing="0" width="100%" style="vertical-align: top;"><tr><td align="left" style="font-size: 0px; padding: 20px;"><div class="text" style="font-family: 微软雅黑, &quot;Microsoft YaHei&quot;; overflow-wrap: break-word; margin: 0px; text-align: center; line-height: 20px; color: rgb(170, 170, 170); font-size: 12px; font-weight: normal;"><div><p style="text-size-adjust: none; word-break: break-word; line-height: 20px; font-size: 12px; margin: 0px;">Copyright © zhongcode 2020 All Right Reserved</p></div></div></td></tr></table></td></tr></tbody></table></div></td></tr></table></center></td></tr></table>

（3）代码测试

public class Main {public static void main(String[] args) throws EmailException, IOException, TemplateException {//1.创建配置类Configuration configuration = new Configuration(Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS);//2.设置模板所在的目录configuration.setDirectoryForTemplateLoading(new File("E:\\tmp\\ftl"));//3.设置字符集configuration.setDefaultEncoding("utf-8");//4.加载模板//模板名自动在模板所在目录寻找Template template = configuration.getTemplate("code.ftl");Map<String, String> data = new HashMap<>();data.put("code", "999999");StringWriter out = new StringWriter();template.process(data, out);// 加载配置文件InputStream is = Main.class.getClassLoader().getResourceAsStream("email.properties");Properties pro = new Properties();pro.load(is);// 创建邮件SendEmail sendEmail = new SendEmail(pro);sendEmail.sendEmail("收件人", "验证码", out.toString());}}

就这样，一封好看的HTML邮件就完成了，任何问题都可以私信我哦