web应用中使用freemarker

springboot整合freemarker，首先加入依赖：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.4.RELEASE</version>
    <relativePath/> 
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
        <!--发现spring-boot-starter-freemarker依赖中包括spring-boot-starter-web依赖-->
      <dependency>
           <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
      </dependency>
</dependencies>

定义Controller类

@Controller
public class UserController {

    @GetMapping("/reg")
    public String reg(){
        return "reg";
    }

    @GetMapping("/logout")
    public String logout(Model model){
        model.addAttribute("username","zhihao.miao");
        model.addAttribute("logout","true");
        return "logout";
    }
}

启动类：

package com.zhihao.miao;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class,args);
    }
}

因为springboot整合freemarker默认的会读取classpath:/templates/下的模版文件，所以一般我们将模版文件放入到classpath:/templates/下即可。
reg.ftl文件内容：

package com.zhihao.miao;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class,args);
    }
}

logout.ftl：

<h1>logout page</h1>
<h1>username is ${username}</h1>
<h1>logout is ${logout}</h1>

启动Application类并启动

也可以修改模版文件的位置，可以使用

spring.freemarker.templateLoaderPath=classpath:/ftl

将上面二个模版文件放在ftl文件夹下重新测试一下即可。

源码查看：
org.springframework.boot.autoconfigure.freemarker.FreeMarkerProperties