为了测试写了一个demo project，为了查看是否成功写了一个index.html用于显示。下面是代码，其中有几个注意事项。
1. index.html要放在resources/templates文件夹下。（这个和spring-boot-starter-thymeleaf的默认配置有关）
2. pom.xml中要添加spring-boot-starter-web和spring-boot-starter-thymeleaf的依赖。
HomeController.java
@Controller public class HomeController { @RequestMapping(value = "/") public String home(){ return "index"; } }
resources/templates/index.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Demo2</title> </head> <body> This is a demo for war package. </body> </html>
pom.xml
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.3.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo</name> <description>Demo project for Spring Boot</description> <properties> <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-thymeleaf</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>