最近做了一个监测k8s服务pod水平伸缩发送邮件的功能（当pod的cpu/内存达到指定阈值后会水平扩展出多个pod、或者指定时间内pod数应扩展到指定数量），一开始写了个格式很low的邮件，像下面这样：
简单邮件
主流程打通，算个v1版本吧，程序员是个追求完美的人，再说这么低逼格的邮件，给客户看，客户也会不满意。那怎么提高邮件的逼格呢？下面写了个简单的demo，v2版本如下：
带模板邮件
感兴趣的小伙伴可以参考，模板可以找你公司前端和美工小姐姐设计。
因为监测k8s服务pod水平伸缩是用go开发的，发送通知邮件提供了个接口，用springboot写的，以下也用springboot做demo
Springboot的pom.xml文件：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>email-demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>email-demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.8.1</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.47</version>
</dependency>
<!--发送邮件的必要依赖-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-mail</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
pod-scale-alarm.html模板文件：
模板中的{0}、{1}这样的占位符后面java代码会替换掉
<body style="color: #666; font-size: 14px; font-family: 'Open Sans',Helvetica,Arial,sans-serif;">
<div class="box-content" style="width: 80%; margin: 20px auto; max-width: 800px; min-width: 600px;">
<div class="header-tip" style="font-size: 12px;
color: #aaa;
text-align: right;
padding-right: 25px;
padding-bottom: 10px;">
Confidential - Scale Alarm Use Only
</div>
<div class="info-top" style="padding: 15px 25px;
border-top-left-radius: 10px;
border-top-right-radius: 10px;
background: {0};
color: #fff;
overflow: hidden;
line-height: 32px;">
<img src="cid:icon-alarm" style="float: left; margin: 0 10px 0 0; width: 32px;" /><div style="color:#010e07"><strong>服务实例水平伸缩通知</strong></div>
</div>
<div class="info-wrap" style="border-bottom-left-radius: 10px;
border-bottom-right-radius: 10px;
border:1px solid #ddd;
overflow: hidden;
padding: 15px 15px 20px;">
<div class="tips" style="padding:15px;">
<p style=" list-style: 160%; margin: 10px 0;">Hi,</p>
<p style=" list-style: 160%; margin: 10px 0;">{1}</p>
</div>
<div class="time" style="text-align: right; color: #999; padding: 0 15px 15px;">{2}</div>
<br>
<table class="list" style="width: 100%; border-collapse: collapse; border-top:1px solid #eee; font-size:12px;">
<thead>
<tr style=" background: #fafafa; color: #333; border-bottom: 1px solid #eee;">
{3}
</tr>
</thead>
<tbody>
{4}
</tbody>
</table>
</div>
</div>
</body>
success-alarm.png图标：
image.png
java代码如下，简单的demo，优化可以自己在项目中去做。
package com.example.emaildemo;
import org.apache.commons.lang3.time.DateFormatUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.mail.javamail.JavaMailSenderImpl;
import org.springframework.mail.javamail.MimeMessageHelper;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.text.MessageFormat;
import java.util.Date;
import java.util.Objects;
import java.util.Properties;
/**
* @program: email-demo
* @description:
* @author: smallsoup
* @create: 2019-01-27 16:44
**/
public class SendEmailUtil {
private static final Logger LOGGER = LoggerFactory.getLogger(SendEmailUtil.class);
public static void main(String[] args) throws MessagingException, IOException {
JavaMailSenderImpl javaMailSender = new JavaMailSenderImpl();
javaMailSender.setUsername("你的邮箱地址");
javaMailSender.setPassword("你的邮箱AUTH密码,不是登陆密码哦,在邮箱的设置里单独开启和设置");
javaMailSender.setHost("smtp.exmail.qq.com");
javaMailSender.setPort(587);
javaMailSender.setDefaultEncoding("UTF-8");
Properties props = new Properties();
props.setProperty("mail.smtp.host", "smtp.exmail.qq.com");
props.setProperty("mail.transport.protocol", "smtp");
props.setProperty("mail.smtp.auth", "true");
props.setProperty("mail.smtp.connectiontimeout", "20000");
props.setProperty("mail.smtp.timeout", "20000");
javaMailSender.setJavaMailProperties(props);
MimeMessage message = javaMailSender.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");
helper.setTo(new String[]{"收件人邮箱"});
helper.setCc("抄送人邮箱");
helper.setFrom("你的邮箱地址");
helper.setSubject("liang subject");
helper.setText(buildContent(), true);
String alarmIconName = "success-alarm.png";
ClassPathResource img = new ClassPathResource(alarmIconName);
if (Objects.nonNull(img)) {
helper.addInline("icon-alarm", img);
}
javaMailSender.send(message);
}
private static String buildContent() throws IOException {
//加载邮件html模板
String fileName = "pod-scale-alarm.html";
InputStream inputStream = ClassLoader.getSystemResourceAsStream(fileName);
BufferedReader fileReader = new BufferedReader(new InputStreamReader(inputStream));
StringBuffer buffer = new StringBuffer();
String line = "";
try {
while ((line = fileReader.readLine()) != null) {
buffer.append(line);
}
} catch (Exception e) {
LOGGER.error("读取文件失败，fileName:{}", fileName, e);
} finally {
inputStream.close();
fileReader.close();
}
String contentText = "以下是服务实例伸缩信息, 敬请查看.<br>below is the information of service instance scale, please check. ";
//邮件表格header
String header = "<td>分区(Namespace)</td><td>服务(Service)</td><td>伸缩结果(Scale Result)</td><td>伸缩原因(Scale Reason)</td><td>当前实例数(Pod instance number)</td>";
StringBuilder linesBuffer = new StringBuilder();
linesBuffer.append("<tr><td>" + "myNamespace" + "</td><td>" + "myServiceName" + "</td><td>" + "myscaleResult" + "</td>" +
"<td>" + "mReason" + "</td><td>" + "my4" + "</td></tr>");
//绿色
String emailHeadColor = "#10fa81";
String date = DateFormatUtils.format(new Date(), "yyyy/MM/dd HH:mm:ss");
//填充html模板中的五个参数
String htmlText = MessageFormat.format(buffer.toString(), emailHeadColor, contentText, date, header, linesBuffer.toString());
//改变表格样式
htmlText = htmlText.replaceAll("<td>", "<td style=\"padding:6px 10px; line-height: 150%;\">");
htmlText = htmlText.replaceAll("<tr>", "<tr style=\"border-bottom: 1px solid #eee; color:#666;\">");
return htmlText;
}
}
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