利用idea和maven作为开发环境，通过springboot+mysql+Jpa完成主要后端开发后，现在往工程里引入Redis数据库缓存和前端freemarker时，发现工程不识别前端freemark的ftl文件。
经过半夜的奋战把问题解决了。现在把错误消息，发生问题时的情景，重试的手段以及最终问题解决的方法在这里分享一下。
画面显示的异常信息：
*************************************
Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.
Thu Oct 26 13:42:36 GMT+08:00 2017
There was an unexpected error (type=Not Found, status=404).
No message available
**************************************
controller:
==================
package com.michael.fm1.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;
import java.util.Map;
@Controller
public class hello {
@RequestMapping(value = "/hello", method = RequestMethod.GET)
public ModelAndView hello(Map<String,Object> map){
map.put("key","value");
ModelAndView modelAndView = new ModelAndView();
modelAndView.setViewName("web");
modelAndView.addObject(map);
return modelAndView;
}
}
===================
springbootApplication:
===================
package com.michael.fm1;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Fm1Application {
public static void main(String[] args) {
SpringApplication.run(Fm1Application.class, args);
}
}
===================
application.properties
===================
空文件
===================
pom.xml
===================
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.7.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</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>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>
<!--<dependency>-->
<!--<groupId>org.freemarker</groupId>-->
<!--<artifactId>freemarker</artifactId>-->
<!--</dependency>-->
</dependencies>
===================
resources/templates下的web.ftl
===================
<h1>this is a tittle</h1>
===================
问题解决的过程：
基于上面的错误信息，经历了各种尝试：
尝试1 新建项目，只留上面最小量的代码。浏览器访问controller，渲染ftl。验证失败。
尝试2 尝试引入thymeLeaf，舍弃fr