What is thymeleaf?
Thymeleaf is facing and independent web server environment of modern java template engine, capable of handling Html, xml, javascript, CSS or even plain text; designed to provide an elegant way to create a template highly maintainable;
Why Thymeleaf template engine?
springBoot official does not recommend the use of jsp, because the embedded Tomcat, jetty container does not support running in a jar in the form of jsp; springBoot provides a large number of template engine, including FreeMarker, Mastache, Thymeleaf and so on; and SpringBoot official recommended to use as a template engine Thymeleaf because thymeleaf provide the perfect support springMVC of;
How to use Thymeleaf template engine?
1. First, add Thymeleaf starter
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
2, HTML file should be placed classpath: under / templates / directory, Thymeleaf can automatically rendered;
3. Add the name space on the html page, there is a grammar tips when using thymeleaf;
<html xmlns:th="http://www.thymeleaf.org">
Use Thymeleaf template engine and into the public statement fragments
For example: In our real development, many of our pages have duplicate code, we can be both written to the common area, it is declared, and then be introduced at the desired page;
<html xmlns:th="http://www.thymeleaf.org">
<head lang="en" id="head">
<meta charset="UTF-8">
<title>梦学谷账单管理系统</title>
<link rel="stylesheet" href="../css/public.css"/>
</head>
<body>
<!--头部-->
<header class="publicHeader" id="header">
<h1>梦学谷账单管理系统</h1>
<div class="publicHeaderR">
<p><span>下午好！</span><span style="color: #fff21b"> Admin</span> , 欢迎你！</p>
<a href="login.html">退出</a>
</div>
</header>
<!--时间-->
<section class="publicTime" id="public_time">
<span id="time">2028年01月01日 11:11 星期一</span>
<a href="#">温馨提示：为了能正常浏览，请使用高版本浏览器！（IE10+）</a>
</section>
As we can see our head, header, publicTime use id made a statement, to be used when we can directly reference it;
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head lang="en" th:replace="main/public :: #head">
</head>
<body>
<!--头部-->
<header class="publicHeader" th:replace="main/public :: #header">
</header>
<!--时间-->
<section class="publicTime" th:replace="main/public :: #public_time">
</section>
: Note: when we declare them and the reference syntax should match
no longer need to fragment 1, when the segment is declared, when we introduced the former name with #;
statement: header.html
<div th:fragment="header_common">
这是th:fragment声明的公共片段
</div>
Quote:
<div th:replace="header :: header_common">
</div>
2, when we use the id selector declared public fragments, fragments need to add # in front of the name;
declare: header.html
<div id="header_common">
这是id声明的公共片段
</div>
Quote:
<div th:replace="header :: #header_common">
</div>
Login page internationalization
1, the first to write an international profile, international content needs to be added to the configuration of the display;
(1) create a file named i18n package folder, "i18n" is an abbreviation for the word internationalization, including a total of 20 letters, i headed letters, n is the last letter;
(2) Second, we need to modify the file character encoding, otherwise the latter will be garbled;
(3) and then a new i18n package at a resourceBundle file; 
(4) the name of the current basis of our international resource file is not the original message, so we need a global configuration file: modification application.properties in;
//这里我们要关闭thymeleaf缓存
spring.thymeleaf.cache=false
//然后指定包名的方式指定基础名
spring.messages.basename=i18n.login
(5) Finally, we need to get the value of property in the international login.html template pages by # {}; (Note: We are here to process the login form, submit a login request, transfers control to the control treatment, and to )
<section class="loginCont">
<!--在这个form表单之上我们添加一个if表达式，当其登录失误的时候对其进行处理-->
<div th:if="${not #strings.isEmpty(msg)}"
th:text="${msg}"
style="color:red; margin-left: 130px"> <!--这里的话对控制层打印出的错误信息进行显示-->
</div>
<!--我们这里的话对login表单进行处理，提交一个login请求，把控制权交给控制器进行处理-->
<form class="loginForm" th:action="@{/login}" th:method="post">
<div class="inputbox">
<label for="user" th:text="#{login.username}">Username</label>
<input id="user" type="text" name="username" required/>
</div>
<div class="inputbox">
<label for="mima" th:text="#{login.password}">Password</label>
<input id="mima" type="password" name="password" required/>
</div>
<div class="subBtn">
<input type="checkbox"/> [[#{login.remember}]]
</div>
<br/>
<div class="subBtn">
<input type="submit" th:value="#{login.submit}"/>
<input type="reset" th:value="#{login.reset}"/>
</div>
<br/>
<!--这里我们添加一个连接点击切换国际化-->
<div style="margin-left: 100px;">
<a th:href="@{/index.html(l='zh_CH')}">中文</a>
<a th:href="@{/index.html(l='en_US')}">English</a>
</div>
</form>
</section>
Custom parser to switch international
/**
* 自定义解析器来切换国际化
* 然后再注入到容器中
*/
public class MyLocalResolver implements LocaleResolver {
/**
* 解析区域信息
*/
@Override
public Locale resolveLocale(HttpServletRequest httpServletRequest) {
System.out.println("区域信息~");
//请求头中的l参数值
String l = httpServletRequest.getParameter("l");
//获取浏览器上的区域信息
Locale locale = httpServletRequest.getLocale();
//获取当前操作系统默认的区域信息
// Locale locale=Locale.getDefault();
//参数有区域信息，则用参数里的区域信息
if (!StringUtils.isEmpty(l)) {
String[] split = l.split("_");
//接收第一个参数为：获取语言代码zh/en，获取国家代码CN/US
locale = new Locale(split[0], split[1]);
}
return locale;
// return null;
}
@Override
public void setLocale(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Locale locale) {
}
}
Then we replace the automatic configuration MVC region parser class;
@Bean
public LocaleResolver localeResolver() {
return new MyLocalResolver();
}
