All template view technologies work similarly, which means FreeMarker and JSP are pretty much the same. Template files and data models are necessary components of template view technology to generate HTML pages.

Data model (Java) + template file (.ftl.jsp file) = output (HTML,XML, source file)Copy the code

JSP makes up for the deficiency of HTML page generated by Servlet in Web system, but it can only be applied to Web system to generate HTML page. FreeMarker works not only on Web systems, but also on Java systems, generating Java, XML, etc., so it’s much more versatile. When used, you need to add dependencies to the project pom.xml file.

< the dependency > < groupId > org. Freemarker < / groupId > < artifactId > freemarker < / artifactId > < version > 2.3.19 < / version > </dependency>Copy the code

When used in SpringMVC, you need to include the corresponding view parser

<bean id="freemarkerConfig" class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer"> <! -- <property name="templateLoaderPath" value="/WEB-INF/ftl/" /> --> <property name="templateLoaderPaths"> <list> <value>/WEB-INF/ftl/</value> <value>classpath:/ftl/</value> </list> </property> <property name="freemarkerSettings"> <props> <prop key="defaultEncoding">UTF-8</prop> <! By default, FreeMarker checks every 5 seconds to see if the template has been updated and reloads and analyzes the template if it has. But checking regularly to see if templates are updated can be time-consuming. If your application is running in production mode and you don't expect templates to be updated very often, you can extend the update delay to an hour or more. You can do this by setting the freemarkerSettings property to template_update_delay, where 0 means reloading each time --> <prop key="template_update_delay">0</prop> <prop key="default_encoding">UTF-8</prop> <prop key="number_format">0.##########</prop> <prop key="datetime_format">yyyy-MM-dd  HH:mm:ss</prop> <prop key="classic_compatible">true</prop> <prop key="template_exception_handler">ignore</prop> </props> </property> </bean> <bean class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver" p:prefix="/" p:suffix=".ftl"> <property name="cache" value="false" /> <property name="viewClass" value="org.springframework.web.servlet.view.freemarker.FreeMarkerView" /> <property name="contentType" value="text/html; charset=UTF-8"></property> <property name="exposeRequestAttributes" value="true" /> <property name="exposeSessionAttributes" value="true" /> <property name="exposeSpringMacroHelpers" value="true" /> <property name="requestContextAttribute" value="base"></property> <property name="order" value="0"></property> </bean>Copy the code

③ Basic grammar

The ${… }

FreeMarker will print the real value to replace the expression in curly braces, which is called Interpolation.

< p style = "max-width: 100%; clear: both;Copy the code

Comments are similar to HTML comments, but they are identified with <#– and –>. Unlike HTML comments, FTL comments do not appear in the output (not on the visitor’s page) because FreeMarker skips them.

<#if condition>
    ...
<#elseif condition2>
    ...
<#elseif condition3>
    ...
<#else>
    ...
</#if>
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FTL tags have some similarities to HTML tags, but they are FreeMarker directives and are not printed in the output. The names of these tags begin with #. (User-defined FTL tags use @ instead of #)

    		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-freemarker</artifactId>
		</dependency>
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② Add related configurations

spring.freemarker.allow-request-override=false
spring.freemarker.allow-session-override=false
spring.freemarker.cache=true
spring.freemarker.charset=UTF-8
spring.freemarker.check-template-location=true
spring.freemarker.content-type=text/html
spring.freemarker.enabled=true  
spring.freemarker.expose-request-attributes=false
spring.freemarker.expose-session-attributes=false
spring.freemarker.expose-spring-macro-helpers=true
spring.freemarker.prefer-file-system-access=false
spring.freemarker.suffix=.ftl
spring.freemarker.template-loader-path=classpath:/templates/
spring.freemarker.settings.template_update_delay=0
spring.freemarker.settings.default_encoding=UTF-8
spring.freemarker.settings.classic_compatible=true 
spring.freemarker.order=1
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One of the most important is the spring. A freemarker. Suffix and spring.. Freemarker template – loader – path, other configuration items can use the default values.

@RequestMapping("/testftl") public String testFtl(Model model) { model.addAttribute("message", "good news!!!" ); return "target"; }Copy the code

Freemarker integrates simple applications from Maven

Freemarker has been used in distributed projects before

The project is on my Github

It can also be downloaded on Baidu Cloud

Note: After importing projects, you need to modify them accordingly. Here I share my Maven repository to prevent all imported projects from being red.