Spring Boot (三)：Thymeleaf 的使用

Thymeleaf 的基本语法

Thymeleaf是Web和独立环境的现代服务器端Java模板引擎，能够处理HTML，XML，JavaScript，CSS甚至纯文本。

Thymeleaf的主要目标是提供一种优雅和高度可维护的创建模板的方式。为了实现这一点，它建立在自然模板的概念上，将其逻辑注入到模板文件中，不会影响模板被用作设计原型。这改善了设计的沟通，弥补了设计和开发团队之间的差距。

Thymeleaf也从一开始就设计了Web标准 - 特别是HTML5 - 允许您创建完全验证的模板，如果这是您需要的

springboot 用thymeleaf 还是挺不错的

温馨提示： 点击右边 展示皮肤 –> 选择 经典白 这个主题可能会更加适合。

一、标准表达式语法

它又分为：

• 消息
• 变量
• 选择表达式
• 链接URL
• 片段
• 文字
• 附加文本
• 字面替代
• 算术运算
• 比较与平等
• 条件表达式
• 默认表达式
• 无操作令牌
• 数据转换/格式化
• 预处理

我就只介绍常用的了

${…} 表达式实际上是在上下文中包含的变量的地图上执行的OGNL（Object-Graph Navigation Language）对象。

1、变量

<p>Today is: <span th:text="${today}">13 february 2011</span>.</p>

意味着 <span> 标签中的内容会被表达式${today}的值所替代，无论模板中它的内容是什么，之所以在模板中“多此一举“地填充它的内容，完全是为了它能够作为原型在浏览器中直接显示出来。
假设today的值为2015年8月14日，那么渲染结果为：<p>Today is: 2015年8月14日.</p>。可见Thymeleaf的基本变量和JSP一样，都使用${.}表示获取变量的值。

2、URL

URL在Web应用模板中占据着十分重要的地位，需要特别注意的是Thymeleaf对于URL的处理是通过语法@{…}来处理的。Thymeleaf支持绝对路径URL：

<a th:href="@{http://www.thymeleaf.org}">Thymeleaf</a>

同时也能够支持相对路径URL：

另外，如果需要Thymeleaf对URL进行渲染，那么务必使用th:href，th:src等属性，下面是一个例子

<!-- Will produce 'http://localhost:8080/gtvg/order/details?orderId=3' (plus rewriting) --><a href="details.html"    th:href="@{http://localhost:8080/gtvg/order/details(orderId=${o.id})}">view</a><!-- Will produce '/gtvg/order/details?orderId=3' (plus rewriting) --><a href="details.html" th:href="@{/order/details(orderId=${o.id})}">view</a><!-- Will produce '/gtvg/order/3/details' (plus rewriting) --><a href="details.html" th:href="@{/order/{orderId}/details(orderId=${o.id})}">view</a>

几点说明：

上例中URL最后的(orderId=${o.id})表示将括号内的内容作为URL参数处理，该语法避免使用字符串拼接，大大提高了可读性@{...}表达式中可以通过{orderId}访问Context中的orderId变量@{/order}是Context相关的相对路径，在渲染时会自动添加上当前Web应用的Context名字，假设context名字为app，那么结果应该是/app/order

3、字符串替换

很多时候可能我们只需要对一大段文字中的某一处地方进行替换，可以通过字符串拼接操作完成：

<span th:text="'Welcome to our application, ' + ${user.name} + '!'">

一种更简洁的方式是：

<span th:text="|Welcome to our application, ${user.name}!|">

当然这种形式限制比较多，|…|中只能包含变量表达式${…}，不能包含其他常量、条件表达式等。

4、运算符

在表达式中可以使用各类算术运算符，例如+, -, *, /, %

th:with="isEven=(${prodStat.count} % 2 == 0)"

逻辑运算符>, <, <=,>=，==,!=都可以使用，唯一需要注意的是使用<,>时需要用它的HTML转义符：

th:if="${prodStat.count} > 1"th:text="'Execution mode is ' + ( (${execMode} == 'dev')? 'Development' : 'Production')"

二、常用的表达式

1、for循环

使用 th:each 标签

<div class="row" >    <div th:each="url,lstat:${links}">        <div class="col-md-2"  th:title="${url.description}"  title="一个人，信你所信，为你所现" >            <strong th:text="${url.link_name}">这个冬天不太冷</strong>            <a href="http://www.lrshuai.top" th:href="${url.link}" th:text="${url.link}" >http://www.lrshuai.top</a>        </div>    </div></div>

lstat称作状态变量，属性有：

• index:当前迭代对象的index（从0开始计算）
• count: 当前迭代对象的index(从1开始计算)
• size:被迭代对象的大小
• current:当前迭代变量
• even/odd:布尔值，当前循环是否是偶数/奇数（从0开始计算）
• first:布尔值，当前循环是否是第一个
• last:布尔值，当前循环是否是最后一个

2、条件求值

If/Unless

demo

<div class="row" >    <div th:each="url,lstat:${links}">        <div class="col-md-2"  th:title="${url.description}" th:if="${lstat.index}%4 == 0" >            <strong th:text="${url.link_name}">这个冬天不太冷</strong>            <a href="http://www.lrshuai.top" th:href="${url.link}" th:text="${url.link}">http://www.lrshuai.top</a>        </div>        <div class="col-md-2 col-md-offset-1" th:title="${url.description}" th:unless="${lstat.index}%4==0">            <strong th:text="${url.link_name}">这个冬天不太冷</strong>            <a href="http://www.lrshuai.top" th:href="${url.link}" th:text="${url.link}"  >http://www.lrshuai.top</a>        </div>    </div></div>

Thymeleaf中使用th:if和th:unless属性进行条件判断，上面的例子中，<div>标签只有在th:if中条件成立时才显示：

th:unless于th:if恰好相反，只有表达式中的条件不成立，才会显示其内容。

Switch

Thymeleaf同样支持多路选择Switch结构：

<div th:switch="${user.role}">  <p th:case="'admin'">User is an administrator</p>  <p th:case="#{roles.manager}">User is a manager</p></div>

默认属性default可以用*表示：

<div th:switch="${user.role}">  <p th:case="'admin'">User is an administrator</p>  <p th:case="#{roles.manager}">User is a manager</p>  <p th:case="*">User is some other thing</p></div>

3、内嵌变量

为了模板更加易用，Thymeleaf还提供了一系列Utility对象（内置于Context中），可以通过#直接访问：

• dates ： java.util.Date的功能方法类。
• calendars : 类似#dates，面向java.util.Calendar
• numbers : 格式化数字的功能方法类
• strings : 字符串对象的功能类
• objects: 对objects的功能类操作。
• bools: 对布尔值求值的功能方法。
• arrays：对数组的功能类方法。
• lists: 对lists功能类方法
• sets
• maps

说说我常用得方法吧，太多了，你也不一定看完

(1)、字符串太多，显示…

# 这里的含义是 如果 atc.text 这个变量多余200个字符，后面显示...<p th:text="${#strings.abbreviate(atc.text,200)}">内容内容内容</p>

(2)、数组判断是否为空

<div th:if="${#lists.isEmpty(arrays)} " class="blog-article">

(3)、request 获取绝对路径

<img th:src="${#httpServletRequest.getContextPath()}+${atc.img}" src="/images/logo.jpg">

常用th标签

标签 说明 例子 th:id 替换id <input th:id="'xxx' + ${collect.id}"/> th:text 文本替换 <p th:text="${collect.description}">description</p> th:utext 支持html的文本替换 <p th:utext="${htmlcontent}">conten</p> th:object 替换对象 <div th:object="${session.user}"> th:value 属性赋值 <input th:value="${user.name}" /> th:with 变量赋值运算 <div th:with="isEven=${prodStat.count}%2==0"></div> th:style 设置样式 th:style="'display:' + @{(${sitrue} ? 'none' : 'inline-block')} + ''" th:onclick 点击事件 th:onclick="'getCollect()'" th:each 属性赋值 tr th:each="user,userStat:${users}"> th:if 判断条件 <a th:if="${userId == collect.userId}" > th:unless 和th:if判断相反 <a th:href="@{/login}" th:unless=${session.user != null}>Login</a> th:href 链接地址 <a th:href="@{/login}" th:unless=${session.user != null}>Login</a> /> th:switch 多路选择 配合th:case 使用 <div th:switch="${user.role}"> th:case th:switch的一个分支 <p th:case="'admin'">User is an administrator</p> th:fragment 布局标签，定义一个代码片段，方便其它地方引用 <div th:fragment="alert"> th:include 布局标签，替换内容到引入的文件 <head th:include="layout :: htmlhead" th:with="title='xx'"></head> /> th:replace 布局标签，替换整个标签到引入的文件 <div th:replace="fragments/header :: title"></div> th:selected selected选择框 选中 th:selected="(${xxx.id} == ${configObj.dd})" th:src 图片类地址引入 <img class="img-responsive" alt="App Logo" th:src="@{/img/logo.png}" /> th:inline 定义js脚本可以使用变量 <script type="text/javascript" th:inline="javascript"> th:action 表单提交的地址 <form action="subscribe.html" th:action="@{/subscribe}"> th:remove 删除某个属性 <tr th:remove="all"> 1.all:删除包含标签和所有的孩子。2.body:不包含标记删除,但删除其所有的孩子。3.tag:包含标记的删除,但不删除它的孩子。4.all-but-first:删除所有包含标签的孩子,除了第一个。5.none:什么也不做。这个值是有用的动态评估。 th:attr 设置标签属性，多个属性可以用逗号分隔 比如<p th:attr="src=@{/image/aa.jpg},title=${title}">内容</p>，这样如果${title}=’这个是title’ 则结果就是<p src="/image/aa.jpg" title="这个是title">内容</p>

html 有的，它几乎都有相对应的标签

下面是一组的API

日期: #dates

/* * ====================================================================== * See javadoc API for class org.thymeleaf.expression.Dates * ====================================================================== *//* * Format date with the standard locale format * Also works with arrays, lists or sets */${#dates.format(date)}${#dates.arrayFormat(datesArray)}${#dates.listFormat(datesList)}${#dates.setFormat(datesSet)}/* * Format date with the ISO8601 format * Also works with arrays, lists or sets */${#dates.formatISO(date)}${#dates.arrayFormatISO(datesArray)}${#dates.listFormatISO(datesList)}${#dates.setFormatISO(datesSet)}/* * Format date with the specified pattern * Also works with arrays, lists or sets */${#dates.format(date, 'dd/MMM/yyyy HH:mm')}${#dates.arrayFormat(datesArray, 'dd/MMM/yyyy HH:mm')}${#dates.listFormat(datesList, 'dd/MMM/yyyy HH:mm')}${#dates.setFormat(datesSet, 'dd/MMM/yyyy HH:mm')}/* * Obtain date properties * Also works with arrays, lists or sets */${#dates.day(date)}                    // also arrayDay(...), listDay(...), etc.${#dates.month(date)}                  // also arrayMonth(...), listMonth(...), etc.${#dates.monthName(date)}              // also arrayMonthName(...), listMonthName(...), etc.${#dates.monthNameShort(date)}         // also arrayMonthNameShort(...), listMonthNameShort(...), etc.${#dates.year(date)}                   // also arrayYear(...), listYear(...), etc.${#dates.dayOfWeek(date)}              // also arrayDayOfWeek(...), listDayOfWeek(...), etc.${#dates.dayOfWeekName(date)}          // also arrayDayOfWeekName(...), listDayOfWeekName(...), etc.${#dates.dayOfWeekNameShort(date)}     // also arrayDayOfWeekNameShort(...), listDayOfWeekNameShort(...), etc.${#dates.hour(date)}                   // also arrayHour(...), listHour(...), etc.${#dates.minute(date)}                 // also arrayMinute(...), listMinute(...), etc.${#dates.second(date)}                 // also arraySecond(...), listSecond(...), etc.${#dates.millisecond(date)}            // also arrayMillisecond(...), listMillisecond(...), etc./* * Create date (java.util.Date) objects from its components */${#dates.create(year,month,day)}${#dates.create(year,month,day,hour,minute)}${#dates.create(year,month,day,hour,minute,second)}${#dates.create(year,month,day,hour,minute,second,millisecond)}/* * Create a date (java.util.Date) object for the current date and time */${#dates.createNow()}${#dates.createNowForTimeZone()}/* * Create a date (java.util.Date) object for the current date (time set to 00:00) */${#dates.createToday()}${#dates.createTodayForTimeZone()}

数字:#numbers

/* * ====================================================================== * See javadoc API for class org.thymeleaf.expression.Numbers * ====================================================================== *//* * ========================== * Formatting integer numbers * ========================== *//*  * Set minimum integer digits. * Also works with arrays, lists or sets */${#numbers.formatInteger(num,3)}${#numbers.arrayFormatInteger(numArray,3)}${#numbers.listFormatInteger(numList,3)}${#numbers.setFormatInteger(numSet,3)}/*  * Set minimum integer digits and thousands separator:  * 'POINT', 'COMMA', 'WHITESPACE', 'NONE' or 'DEFAULT' (by locale). * Also works with arrays, lists or sets */${#numbers.formatInteger(num,3,'POINT')}${#numbers.arrayFormatInteger(numArray,3,'POINT')}${#numbers.listFormatInteger(numList,3,'POINT')}${#numbers.setFormatInteger(numSet,3,'POINT')}/* * ========================== * Formatting decimal numbers * ========================== *//* * Set minimum integer digits and (exact) decimal digits. * Also works with arrays, lists or sets */${#numbers.formatDecimal(num,3,2)}${#numbers.arrayFormatDecimal(numArray,3,2)}${#numbers.listFormatDecimal(numList,3,2)}${#numbers.setFormatDecimal(numSet,3,2)}/* * Set minimum integer digits and (exact) decimal digits, and also decimal separator. * Also works with arrays, lists or sets */${#numbers.formatDecimal(num,3,2,'COMMA')}${#numbers.arrayFormatDecimal(numArray,3,2,'COMMA')}${#numbers.listFormatDecimal(numList,3,2,'COMMA')}${#numbers.setFormatDecimal(numSet,3,2,'COMMA')}/* * Set minimum integer digits and (exact) decimal digits, and also thousands and  * decimal separator. * Also works with arrays, lists or sets */${#numbers.formatDecimal(num,3,'POINT',2,'COMMA')}${#numbers.arrayFormatDecimal(numArray,3,'POINT',2,'COMMA')}${#numbers.listFormatDecimal(numList,3,'POINT',2,'COMMA')}${#numbers.setFormatDecimal(numSet,3,'POINT',2,'COMMA')}/*  * ===================== * Formatting currencies * ===================== */${#numbers.formatCurrency(num)}${#numbers.arrayFormatCurrency(numArray)}${#numbers.listFormatCurrency(numList)}${#numbers.setFormatCurrency(numSet)}/*  * ====================== * Formatting percentages * ====================== */${#numbers.formatPercent(num)}${#numbers.arrayFormatPercent(numArray)}${#numbers.listFormatPercent(numList)}${#numbers.setFormatPercent(numSet)}/*  * Set minimum integer digits and (exact) decimal digits. */${#numbers.formatPercent(num, 3, 2)}${#numbers.arrayFormatPercent(numArray, 3, 2)}${#numbers.listFormatPercent(numList, 3, 2)}${#numbers.setFormatPercent(numSet, 3, 2)}/* * =============== * Utility methods * =============== *//* * Create a sequence (array) of integer numbers going * from x to y */${#numbers.sequence(from,to)}${#numbers.sequence(from,to,step)}

字符串:#strings

/* * Null-safe toString() */${#strings.toString(obj)}                           // also array*, list* and set*/* * Check whether a String is empty (or null). Performs a trim() operation before check * Also works with arrays, lists or sets */${#strings.isEmpty(name)}${#strings.arrayIsEmpty(nameArr)}${#strings.listIsEmpty(nameList)}${#strings.setIsEmpty(nameSet)}/* * Perform an 'isEmpty()' check on a string and return it if false, defaulting to * another specified string if true. * Also works with arrays, lists or sets */${#strings.defaultString(text,default)}${#strings.arrayDefaultString(textArr,default)}${#strings.listDefaultString(textList,default)}${#strings.setDefaultString(textSet,default)}/* * Check whether a fragment is contained in a String * Also works with arrays, lists or sets */${#strings.contains(name,'ez')}                     // also array*, list* and set*${#strings.containsIgnoreCase(name,'ez')}           // also array*, list* and set*/* * Check whether a String starts or ends with a fragment * Also works with arrays, lists or sets */${#strings.startsWith(name,'Don')}                  // also array*, list* and set*${#strings.endsWith(name,endingFragment)}           // also array*, list* and set*/* * Substring-related operations * Also works with arrays, lists or sets */${#strings.indexOf(name,frag)}                      // also array*, list* and set*${#strings.substring(name,3,5)}                     // also array*, list* and set*${#strings.substringAfter(name,prefix)}             // also array*, list* and set*${#strings.substringBefore(name,suffix)}            // also array*, list* and set*${#strings.replace(name,'las','ler')}               // also array*, list* and set*/* * Append and prepend * Also works with arrays, lists or sets */${#strings.prepend(str,prefix)}                     // also array*, list* and set*${#strings.append(str,suffix)}                      // also array*, list* and set*/* * Change case * Also works with arrays, lists or sets */${#strings.toUpperCase(name)}                       // also array*, list* and set*${#strings.toLowerCase(name)}                       // also array*, list* and set*/* * Split and join */${#strings.arrayJoin(namesArray,',')}${#strings.listJoin(namesList,',')}${#strings.setJoin(namesSet,',')}${#strings.arraySplit(namesStr,',')}                // returns String[]${#strings.listSplit(namesStr,',')}                 // returns List<String>${#strings.setSplit(namesStr,',')}                  // returns Set<String>/* * Trim * Also works with arrays, lists or sets */${#strings.trim(str)}                               // also array*, list* and set*/* * Compute length * Also works with arrays, lists or sets */${#strings.length(str)}                             // also array*, list* and set*/* * Abbreviate text making it have a maximum size of n. If text is bigger, it * will be clipped and finished in "..." * Also works with arrays, lists or sets */${#strings.abbreviate(str,10)}                      // also array*, list* and set*/* * Convert the first character to upper-case (and vice-versa) */${#strings.capitalize(str)}                         // also array*, list* and set*${#strings.unCapitalize(str)}                       // also array*, list* and set*/* * Convert the first character of every word to upper-case */${#strings.capitalizeWords(str)}                    // also array*, list* and set*${#strings.capitalizeWords(str,delimiters)}         // also array*, list* and set*/* * Escape the string */${#strings.escapeXml(str)}                          // also array*, list* and set*${#strings.escapeJava(str)}                         // also array*, list* and set*${#strings.escapeJavaScript(str)}                   // also array*, list* and set*${#strings.unescapeJava(str)}                       // also array*, list* and set*${#strings.unescapeJavaScript(str)}                 // also array*, list* and set*/* * Null-safe comparison and concatenation */${#strings.equals(first, second)}${#strings.equalsIgnoreCase(first, second)}${#strings.concat(values...)}${#strings.concatReplaceNulls(nullValue, values...)}/* * Random */${#strings.randomAlphanumeric(count)}

布尔:#bools

/* * Evaluate a condition in the same way that it would be evaluated in a th:if tag * (see conditional evaluation chapter afterwards). * Also works with arrays, lists or sets */${#bools.isTrue(obj)}${#bools.arrayIsTrue(objArray)}${#bools.listIsTrue(objList)}${#bools.setIsTrue(objSet)}/* * Evaluate with negation * Also works with arrays, lists or sets */${#bools.isFalse(cond)}${#bools.arrayIsFalse(condArray)}${#bools.listIsFalse(condList)}${#bools.setIsFalse(condSet)}/* * Evaluate and apply AND operator * Receive an array, a list or a set as parameter */${#bools.arrayAnd(condArray)}${#bools.listAnd(condList)}${#bools.setAnd(condSet)}/* * Evaluate and apply OR operator * Receive an array, a list or a set as parameter */${#bools.arrayOr(condArray)}${#bools.listOr(condList)}${#bools.setOr(condSet)}

数组 :#arrays

/* * Converts to array, trying to infer array component class. * Note that if resulting array is empty, or if the elements * of the target object are not all of the same class, * this method will return Object[]. */${#arrays.toArray(object)}/* * Convert to arrays of the specified component class. */${#arrays.toStringArray(object)}${#arrays.toIntegerArray(object)}${#arrays.toLongArray(object)}${#arrays.toDoubleArray(object)}${#arrays.toFloatArray(object)}${#arrays.toBooleanArray(object)}/* * Compute length */${#arrays.length(array)}/* * Check whether array is empty */${#arrays.isEmpty(array)}/* * Check if element or elements are contained in array */${#arrays.contains(array, element)}${#arrays.containsAll(array, elements)}

参考文献：http://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html

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