SpringBoot中Thymeleaf模板引擎的使用
SpringBoot中Thymeleaf模板引擎的使用
除了REST Web服务之外，我们还可以使用Spring MVC来服务动态HTML内容。SpringMVC支持多种模板技术，包括Thymeleaf、FreeMarker、JSP。当然，许多其他的模板引擎也有SpringMVC集成。
其中Spring Boot中包含了以下模板引擎的自动配置支持：
- Thymeleaf（用的最多）
- FreeMarker
- JSP（不推荐使用）
- Mustache
在早期开发的时候，我们完成的都是静态页面也就是html页面，随着时间轴的发展，慢慢的引入了jsp页面，当在后端服务查询到数据之后可以转发到jsp页面，可以轻松的使用jsp页面来实现数据的显示及交互，jsp有非常强大的功能，但是，在使用springboot的时候，整个项目是以jar包的方式运行而不是war包，而且还嵌入了tomcat容器，因此，在默认情况下是不支持jsp页面的。如果直接以纯静态页面的方式会给我们的开发带来很大的麻烦，springboot推荐使用模板引擎。
模板引擎有很多种，jsp,freemarker,thymeleaf，模板引擎的作用就是我们来写一个页面模板，比如有些值呢，是动态的，我们写一些表达式。而这些值，从哪来呢，我们来组装一些数据，我们把这些数据找到。然后把这个模板和这个数据交给我们模板引擎，模板引擎按照我们这个数据帮你把这表达式解析、填充到我们指定的位置，然后把这个数据最终生成一个我们想要的内容给我们写出去，这就是我们这个模板引擎，不管是jsp还是其他模板引擎，都是这个思想。只不过不同的模板引擎语法不同而已，下面重点学习下springboot推荐使用的thymeleaf模板引擎，语法简单且功能强大。
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1、thymeleaf的介绍
官网地址：https://www.thymeleaf.org/
thymeleaf在github的地址：https://github.com/thymeleaf/thymeleaf
中文网站：https://raledong.gitbooks.io/using-thymeleaf/content/
导入依赖：
<dependency>
<groupId>org.thymeleafgroupId>
<artifactId>thymeleaf-spring5artifactId>
dependency>
<dependency>
<groupId>org.thymeleaf.extrasgroupId>
<artifactId>thymeleaf-extras-java8timeartifactId>
dependency>
在springboot中有专门的thymeleaf配置类：ThymeleafProperties
@ConfigurationProperties(prefix = "spring.thymeleaf")
public class ThymeleafProperties {
private static final Charset DEFAULT_ENCODING = StandardCharsets.UTF_8;
public static final String DEFAULT_PREFIX = "classpath:/templates/";
public static final String DEFAULT_SUFFIX = ".html";
/**
* Whether to check that the template exists before rendering it.
*/
private boolean checkTemplate = true;
/**
* Whether to check that the templates location exists.
*/
private boolean checkTemplateLocation = true;
/**
* Prefix that gets prepended to view names when building a URL.
*/
private String prefix = DEFAULT_PREFIX;
/**
* Suffix that gets appended to view names when building a URL.
*/
private String suffix = DEFAULT_SUFFIX;
/**
* Template mode to be applied to templates. See also Thymeleaf's TemplateMode enum.
*/
private String mode = "HTML";
/**
* Template files encoding.
*/
private Charset encoding = DEFAULT_ENCODING;
/**
* Whether to enable template caching.
*/
private boolean cache = true;
2、thymeleaf使用模板
在java代码中写入如下代码：
@RequestMapping("/hello")
public String hello(Model model){
model.addAttribute("msg","Hello");
//classpath:/templates/hello.html
return "hello";
}
html页面中写入如下代码：
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<body>
<h1>Helloh1>
<div th:text="${msg}">div>
body>
html>
3、thymeleaf的表达式语法
Simple expressions:
Variable Expressions: ${...}
Selection Variable Expressions: *{...}
Message Expressions: #{...}
Link URL Expressions: @{...}
Fragment Expressions: ~{...}
Literals
Text literals: 'one text', 'Another one!',…
Number literals: 0, 34, 3.0, 12.3,…
Boolean literals: true, false
Null literal: null
Literal tokens: one, sometext, main,…
Text operations:
String concatenation: +
Literal substitutions: |The name is ${name}|
Arithmetic operations:
Binary operators: +, -, *, /, %
Minus sign (unary operator): -
Boolean operations:
Binary operators: and, or
Boolean negation (unary operator): !, not
Comparisons and equality:
Comparators: >, <, >=, <= (gt, lt, ge, le)
Equality operators: ==, != (eq, ne)
Conditional operators:
If-then: (if) ? (then)
If-then-else: (if) ? (then) : (else)
Default: (value) ?: (defaultvalue)
Special tokens:
No-Operation: _
4、thymeleaf实例演示
1、th的常用属性值
一、th:text ：设置当前元素的文本内容，相同功能的还有th:utext，两者的区别在于前者不会转义html标签，后者会。优先级不高：order=7
二、th:value：设置当前元素的value值，类似修改指定属性的还有th:src，th:href。优先级不高：order=6
三、th:each：遍历循环元素，和th:text或th:value一起使用。注意该属性修饰的标签位置，详细往后看。优先级很高：order=2
四、th:if：条件判断，类似的还有th:unless，th:switch，th:case。优先级较高：order=3
五、th:insert：代码块引入，类似的还有th:replace，th:include，三者的区别较大，若使用不恰当会破坏html结构，常用于公共代码块提取的场景。优先级最高：order=1
六、th:fragment：定义代码块，方便被th:insert引用。优先级最低：order=8
七、th:object：声明变量，一般和*{}一起配合使用，达到偷懒的效果。优先级一般：order=4
八、th:attr：修改任意属性，实际开发中用的较少，因为有丰富的其他th属性帮忙，类似的还有th:attrappend，th:attrprepend。优先级一般：order=5
thymeleaf.html
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Titletitle>
head>
<body>
<p th:text="${thText}">p>
<p th:utext="${thUText}">p>
<input type="text" th:value="${thValue}">
<div th:each="message:${thEach}">
<p th:text="${message}">p>
div>
<div>
<p th:text="${message}" th:each="message:${thEach}">p>
div>
<p th:text="${thIf}" th:if="${not #strings.isEmpty(thIf)}">p>
<div th:object="${thObject}">
<p>name:<span th:text="*{name}"/>p>
<p>age:<span th:text="*{age}"/>p>
<p>gender:<span th:text="*{gender}"/>p>
div>
body>
html>
ThymeleafController.java
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
public class ThymeleafController {
@RequestMapping("thymeleaf")
public String thymeleaf(ModelMap map){
map.put("thText","th:text设置文本内容 加粗");
map.put("thUText","th:utext 设置文本内容 加粗");
map.put("thValue","thValue 设置当前元素的value值");
map.put("thEach","Arrays.asList(\"th:each\", \"遍历列表\")");
map.put("thIf","msg is not null");
map.put("thObject",new Person("zhangsan",12,"男"));
return "thymeleaf";
}
}
2、标准表达式语法
${…} 变量表达式，Variable Expressions
*{…} 选择变量表达式，Selection Variable Expressions
一、可以获取对象的属性和方法
二、可以使用ctx，vars，locale，request，response，session，servletContext内置对象
session.setAttribute("user","zhangsan");
th:text="${session.user}"
三、可以使用dates，numbers，strings，objects，arrays，lists，sets，maps等内置方法
standardExpression.html
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>thymeleaf内置方法title>
head>
<body>
<h3>#strings h3>
<div th:if="${not #strings.isEmpty(Str)}" >
<p>Old Str : <span th:text="${Str}"/>p>
<p>toUpperCase : <span th:text="${#strings.toUpperCase(Str)}"/>p>
<p>toLowerCase : <span th:text="${#strings.toLowerCase(Str)}"/>p>
<p>equals : <span th:text="${#strings.equals(Str, 'blog')}"/>p>
<p>equalsIgnoreCase : <span th:text="${#strings.equalsIgnoreCase(Str, 'blog')}"/>p>
<p>indexOf : <span th:text="${#strings.indexOf(Str, 'r')}"/>p>
<p>substring : <span th:text="${#strings.substring(Str, 2, 4)}"/>p>
<p>replace : <span th:text="${#strings.replace(Str, 'it', 'IT')}"/>p>
<p>startsWith : <span th:text="${#strings.startsWith(Str, 'it')}"/>p>
<p>contains : <span th:text="${#strings.contains(Str, 'IT')}"/>p>
div>
<h3>#numbers h3>
<div>
<p>formatDecimal 整数部分随意，小数点后保留两位，四舍五入: <span th:text="${#numbers.formatDecimal(Num, 0, 2)}"/>p>
<p>formatDecimal 整数部分保留五位数，小数点后保留两位，四舍五入: <span th:text="${#numbers.formatDecimal(Num, 5, 2)}"/>p>
div>
<h3>#bools h3>
<div th:if="${#bools.isTrue(Bool)}">
<p th:text="${Bool}">p>
div>
<h3>#arrays h3>
<div th:if="${not #arrays.isEmpty(Array)}">
<p>length : <span th:text="${#arrays.length(Array)}"/>p>
<p>contains : <span th:text="${#arrays.contains(Array,2)}"/>p>
<p>containsAll : <span th:text="${#arrays.containsAll(Array, Array)}"/>p>
div>
<h3>#lists h3>
<div th:if="${not #lists.isEmpty(List)}">
<p>size : <span th:text="${#lists.size(List)}"/>p>
<p>contains : <span th:text="${#lists.contains(List, 0)}"/>p>
<p>sort : <span th:text="${#lists.sort(List)}"/>p>
div>
<h3>#maps h3>
<div th:if="${not #maps.isEmpty(hashMap)}">
<p>size : <span th:text="${#maps.size(hashMap)}"/>p>
<p>containsKey : <span th:text="${#maps.containsKey(hashMap, 'thName')}"/>p>
<p>containsValue : <span th:text="${#maps.containsValue(hashMap, '#maps')}"/>p>
div>
<h3>#dates h3>
<div>
<p>format : <span th:text="${#dates.format(Date)}"/>p>
<p>custom format : <span th:text="${#dates.format(Date, 'yyyy-MM-dd HH:mm:ss')}"/>p>
<p>day : <span th:text="${#dates.day(Date)}"/>p>
<p>month : <span th:text="${#dates.month(Date)}"/>p>
<p>monthName : <span th:text="${#dates.monthName(Date)}"/>p>
<p>year : <span th:text="${#dates.year(Date)}"/>p>
<p>dayOfWeekName : <span th:text="${#dates.dayOfWeekName(Date)}"/>p>
<p>hour : <span th:text="${#dates.hour(Date)}"/>p>
<p>minute : <span th:text="${#dates.minute(Date)}"/>p>
<p>second : <span th:text="${#dates.second(Date)}"/>p>
<p>createNow : <span th:text="${#dates.createNow()}"/>p>
div>
body>
html>
ThymeleafController.java
@RequestMapping("standardExpression")
public String standardExpression(ModelMap map){
map.put("Str", "Blog");
map.put("Bool", true);
map.put("Array", new Integer[]{1,2,3,4});
map.put("List", Arrays.asList(1,3,2,4,0));
Map hashMap = new HashMap();
hashMap.put("thName", "${#...}");
hashMap.put("desc", "变量表达式内置方法");
map.put("Map", hashMap);
map.put("Date", new Date());
map.put("Num", 888.888D);
return "standardExpression";
}
@{…} 链接表达式，Link URL Expressions
<link th:href="@{/webjars/bootstrap/4.0.0/css/bootstrap.css}" rel="stylesheet">
<link th:href="@{/main/css/123.css}" rel="stylesheet">
<form class="form-login" th:action="@{/user/login}" th:method="post" >
<a class="btn btn-sm" th:href="@{/login.html(l='zh_CN')}">中文a>
<a class="btn btn-sm" th:href="@{/login.html(l='en_US')}">Englisha>
#{…} 消息表达式，Message Expressions
~{…} 代码块表达式，Fragment Expressions
fragment.html
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Titletitle>
head>
<body>
<footer th:fragment="copy">
2019 The Good Thymes Virtual Grocery
footer>
<div th:insert="fragment::copy">div>
<div th:replace="fragment::copy">div>
<div th:include="fragment::copy">div>
<div>
<footer>
© 2011 The Good Thymes Virtual Grocery
footer>
div>
<footer>
© 2011 The Good Thymes Virtual Grocery
footer>
<div>
© 2011 The Good Thymes Virtual Grocery
div>
body>
html>
5、国际化的配置
在很多应用场景下，我们需要实现页面的国际化，springboot对国际化有很好的支持， 下面来演示对应的效果。
1、在idea中设置统一的编码格式，file->settings->Editors->File Encoding,选择编码格式为utf-8
2、在resources资源文件下创建一个i8n的目录，创建一个login.properties的文件，还有login_zh_CN.properties,idea会自动识别国际化操作
3、创建三个不同的文件，名称分别是：login.properties，login_en_US.properties，login_zh_CN.properties
内容如下：
#login.properties
login.password=密码1
login.remmber=记住我1
login.sign=登录1
login.username=用户名1
#login_en_US.properties
login.password=Password
login.remmber=Remember Me
login.sign=Sign In
login.username=Username
#login_zh_CN.properties
login.password=密码~
login.remmber=记住我~
login.sign=登录~
login.username=用户名~
4、配置国际化的资源路径
spring:
messages:
basename: i18n/login
5、编写html页面
初始html页面
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8"/>
<title>Titletitle>
head>
<body>
<form action="" method="post">
<label >Usernamelabel>
<input type="text" name="username" placeholder="Username" >
<label >Passwordlabel>
<input type="password" name="password" placeholder="Password" >
<br> <br>
<div>
<label>
<input type="checkbox" value="remember-me"/> Remember Me
label>
div>
<br>
<button type="submit">Sign inbutton>
<br> <br>
<a>中文a>
<a>Englisha>
form>
body>
html>
修改后的页面
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8"/>
<title>Titletitle>
head>
<body>
<form action="" method="post">
<label th:text="#{login.username}">Usernamelabel>
<input type="text" name="username" placeholder="Username" th:placeholder="#{login.username}">
<label th:text="#{login.password}">Passwordlabel>
<input type="password" name="password" placeholder="Password" th:placeholder="#{login.password}">
<br> <br>
<div>
<label>
<input type="checkbox" value="remember-me"/> [[#{login.remmber}]]
label>
div>
<br>
<button type="submit" th:text="#{login.sign}">Sign inbutton>
<br> <br>
<a>中文a>
<a>Englisha>
form>
body>
html>
可以看到通过浏览器的切换语言已经能够实现，想要通过超链接实现的话，如下所示：
添加WebMVCConfig.java代码
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Locale;
@Configuration
public class WebMVCConfig implements WebMvcConfigurer {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/").setViewName("login");
registry.addViewController("/login.html").setViewName("login");
}
@Bean
public LocaleResolver localeResolver(){
return new NativeLocaleResolver();
}
protected static class NativeLocaleResolver implements LocaleResolver{
@Override
public Locale resolveLocale(HttpServletRequest request) {
String language = request.getParameter("language");
Locale locale = Locale.getDefault();
if(!StringUtils.isEmpty(language)){
String[] split = language.split("_");
locale = new Locale(split[0],split[1]);
}
return locale;
}
@Override
public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {
}
}
}
login.html页面修改为：
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8"/>
<title>Titletitle>
head>
<body>
<form action="" method="post">
<label th:text="#{login.username}">Usernamelabel>
<input type="text" name="username" placeholder="Username" th:placeholder="#{login.username}">
<label th:text="#{login.password}">Passwordlabel>
<input type="password" name="password" placeholder="Password" th:placeholder="#{login.password}">
<br> <br>
<div>
<label>
<input type="checkbox" value="remember-me"/> [[#{login.remmber}]]
label>
div>
<br>
<button type="submit" th:text="#{login.sign}">Sign inbutton>
<br> <br>
<a th:href="@{/login.html(language='zh_CN')}">中文a>
<a th:href="@{/login.html(language='en_US')}">Englisha>
form>
body>
html>
国际化的源码解释：
//MessageSourceAutoConfiguration
public class MessageSourceAutoConfiguration {
private static final Resource[] NO_RESOURCES = new Resource[0];
public MessageSourceAutoConfiguration() {
}
@Bean
@ConfigurationProperties(prefix = "spring.messages") //我们的配置文件可以直接放在类路径下叫： messages.properties， 就可以进行国际化操作了
public MessageSourceProperties messageSourceProperties() {
return new MessageSourceProperties();
}
@Bean
public MessageSource messageSource(MessageSourceProperties properties) {
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
if (StringUtils.hasText(properties.getBasename())) {
//设置国际化文件的基础名（去掉语言国家代码的）
messageSource.setBasenames(StringUtils.commaDelimitedListToStringArray(StringUtils.trimAllWhitespace(properties.getBasename())));
}
if (properties.getEncoding() != null) {
messageSource.setDefaultEncoding(properties.getEncoding().name());
}
messageSource.setFallbackToSystemLocale(properties.isFallbackToSystemLocale());
Duration cacheDuration = properties.getCacheDuration();
if (cacheDuration != null) {
messageSource.setCacheMillis(cacheDuration.toMillis());
}
messageSource.setAlwaysUseMessageFormat(properties.isAlwaysUseMessageFormat());
messageSource.setUseCodeAsDefaultMessage(properties.isUseCodeAsDefaultMessage());
return messageSource;
}
}
//WebMvcAutoConfiguration
@Bean
@ConditionalOnMissingBean
@ConditionalOnProperty(prefix = "spring.mvc", name = "locale")
public LocaleResolver localeResolver() {
if (this.mvcProperties.getLocaleResolver() == WebMvcProperties.LocaleResolver.FIXED) {
return new FixedLocaleResolver(this.mvcProperties.getLocale());
}
AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
return localeResolver;
}
//AcceptHeaderLocaleResolver
@Override
public Locale resolveLocale(HttpServletRequest request) {
Locale defaultLocale = getDefaultLocale();
if (defaultLocale != null && request.getHeader("Accept-Language") == null) {
return defaultLocale;
}
Locale requestLocale = request.getLocale();
List<Locale> supportedLocales = getSupportedLocales();
if (supportedLocales.isEmpty() || supportedLocales.contains(requestLocale)) {
return requestLocale;
}
Locale supportedLocale = findSupportedLocale(request, supportedLocales);
if (supportedLocale != null) {
return supportedLocale;
}
return (defaultLocale != null ? defaultLocale : requestLocale);
}