spring boot: Whitelabel Error Page的解决方案

          初次使用spring boot，按照其官网Building a RESTful Web Service搭建运行一个demo，代码如下:

pom.xml

	4.0.0
	
	personal.timeless
	CommentSystem
	war
	0.0.1-SNAPSHOT
	
	CommentSystem Maven Webapp
	http://maven.apache.org
	
	
        org.springframework.boot
        spring-boot-starter-parent
        1.4.2.RELEASE
    

    
        
            org.springframework.boot
            spring-boot-starter-web
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
        
            com.jayway.jsonpath
            json-path
            test
        
    

    
        1.8
    


    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
    

    
        
            spring-releases
            https://repo.spring.io/libs-release
        
    
    
        
            spring-releases
            https://repo.spring.io/libs-release
        
    

controller Comment.java

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Comments {
	
	@RequestMapping("/greeting")
    public String greeting(@RequestParam(value="name", defaultValue="World") String name) {
        return name;
    }
}

主文件 App.java

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

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

运行起来没报错，但是打开浏览器输入地址http://localhost:8080/greeting出现以下页面

检查地址没问题，核对jar包也正确。google,有说少jar包，按照回答添加以后也无济于事。折腾了一会找到了原因

竟然时目录文件结构问题，最后附上官网说明http://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/#using-boot-structuring-your-code

14.2 Locating the main application class
We generally recommend that you locate your main application class in a root package above other classes. The @EnableAutoConfiguration annotation is often placed on your main class, and it implicitly defines a base “search package” for certain items. For example, if you are writing a JPA application, the package of the @EnableAutoConfiguration annotated class will be used to search for @Entity items.

Using a root package also allows the @ComponentScan annotation to be used without needing to specify a basePackage attribute. You can also use the @SpringBootApplication annotation if your main class is in the root package.

Here is a typical layout:

com
 +- example
     +- myproject
         +- Application.java
         |
         +- domain
         |   +- Customer.java
         |   +- CustomerRepository.java
         |
         +- service
         |   +- CustomerService.java
         |
         +- web
             +- CustomerController.java