1. 概述

本节的标准表达式语法包含如下内容：

• 生成URL地址:@{}
• 表达式工具对象:Expression Utility Objects

2. 主代码

2.1. 公共代码

ExpressionsCtl：Control类

@Controller
@RequestMapping("/expressions")
public class ExpressionsCtl {
    /** * 处理URL * * @param modeMap * @return */
    @RequestMapping("/url")
    public String url(ModelMap modeMap){
        modeMap.put("id", "123");
        return "expressions/url";
    }
    /** * 表达式工具对象:Expression Utility Objects * */
    @RequestMapping("/utility")
    public String utility(ModelMap modeMap){
        return "expressions/utility";
    }
}

url()方法转到url.html, 包含urls的用法代码; utility()方法转到utility.html，包含表达式工具对象相关代码。

2.2. 生成URL地址@{}

演示如下功能

• th:href生成的值替换
• url中加入变量值(orderId=${id})做为url的请求参数

==================== 动态生成URL ===============================<br/>
<!-- th:href生成的值替换<a>的href值; (orderId=${id})做为url的请求参数 -->
http://localhost:8080/gtvg/order/details?orderId=123 --> <a href="details.html" th:href="@{http://localhost:8080/gtvg/order/details(orderId=${id})}">view</a> <br />
<!-- 生成：/order/details?orderId=123 -->
/order/details?orderId=123 --> <a href="details.html" th:href="@{/order/details(orderId=${id})}">view</a> <br />
<!-- 替换url中变量值，生成/order/123/details -->
/order/123/details --> <a href="details.html" th:href="@{/order/{orderId}/details(orderId=${id})}">view</a> <br />

输出: “–>”的左边是语法，右边是对应的输出(这里以源码方式显示)

==================== 动态生成URL ===============================<br />
<!-- th:href生成的值替换<a>的href值; (orderId=${id})做为url的请求参数 -->
http://localhost:8080/gtvg/order/details?orderId=123 --> <a href="http://localhost:8080/gtvg/order/details?orderId=123">view</a> <br />
<!-- 生成：/order/details?orderId=123 -->
/order/details?orderId=123 --> <a href="/order/details?orderId=123">view</a> <br />
<!-- 替换url中变量值，生成/order/123/details -->
/order/123/details --> <a href="/order/123/details">view</a> <br />

2.3. 表达式工具对象:Expression Utility Objects

thymeleaf有很多工具类，所有工具类如下：

• #execInfo: information about the template being processed.
• #messages: methods for obtaining externalized messages inside variables expressions, in the same way as they would be obtained
  using #{…} syntax.
• #uris: methods for escaping parts of URLs/URIs
• #conversions: methods for executing the configured conversion service (if any).
• #dates: methods for java.util.Date objects: formatting,
  component extraction, etc.
• #calendars: analogous to #dates, but for
  java.util.Calendar objects.
• #numbers: methods for formatting
  numeric objects.
• #strings: methods for String objects: contains,
  startsWith, prepending/appending, etc.
• #objects: methods for objects in general.
• #bools: methods for boolean evaluation.
• #arrays: methods for arrays.
• #lists: methods for lists.
• #sets: methods for sets.
• #maps: methods for maps.
• #aggregates: methods for creating aggregates on arrays or collections.
• #ids: methods for dealing with id attributes that might be repeated (for example, as a result of an iteration).

这里只列出#messages，#uris的用法，其它工具类用法见官方的用法详细见这里，

==================== #messages ===============================<br/>
<!-- #messages加载外部属性文件的key，对应接口org.thymeleaf.expression.Messages 这里只列出一种用法，其他可以用法也是类似 详细见：http://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#messages-1 -->
${#messages.msgOrNull('home.welcome.replace','message')} --> <span th:text="${#messages.msgOrNull('home.welcome.replace','message')}" ></span>
<br />
==================== #uris ===============================<br/>
<!-- #uris: URL/URI的工具类，对应接口org.thymeleaf.expression.Uris 详细见： http://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#urisurls -->
${#uris.escapePath('http://blog.csdn.net/hry2015/')} --> <span th:text="${#uris.escapePath('http://blog.csdn.net/hry2015/')}" ></span>

输出: “–>”的左边是语法，右边是对应的输出

==================== #messages ===============================
${#messages.msgOrNull('home.welcome.replace','message')} --> welcome thymeleaf, message! 
==================== #uris ===============================
${#uris.escapePath('http://blog.csdn.net/hry2015/')} --> http://blog.csdn.net/hry2015/

3. 代码

详细代码见Github