【Spring Boot 基础】快速构建项目，在浏览器和后台显示输出结果

ゝ一世哀愁。 2023-10-11 21:22 0阅读 0赞

**一、代码演示及操作步骤**

1、创建Web项目

![b861ba42112349ef84403162816f46bd.png][]

![9c621ca12c3346219a573e7379dec228.png][]

2、项目结构

在与Application同级目录下创建Controller。重点关注pom、Application、Controller三个文件。

![9c6c21408aa445118807db867d7ce7ab.png][]

**3、代码练习**

**3.1在浏览器输出Hello World**

1）Controller

package com.lc.springboot_testbilbil;
    
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class HelloController {
        @RequestMapping("/hello")
        public String hello(){
            return "Hello World!";
        }
    }

2)Application

package com.lc.springboot_testbilbil;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    @SpringBootApplication
    public class SpringBootTestBilBilApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(SpringBootTestBilBilApplication.class, args);
        }
    
    }

3）运行结果：

后台：

![fe5301577afa48b6bee702814b1ec056.png][]

根据后台提示的端口8080，浏览器地址输入localhost:8080/hello可以得到代码输出结果：

![ccb5629581bd4953974f9ef550c62638.png][]

**3.2 YAML数据格式和数据获取**

配置文件在resources根目录下。在同一级目录下优先级从高到低为：properties>yml>yaml。

1）创建yml文件

![92d2e04ec3b94c0b8d62a1ce4b5616fb.png][]

2）.yml

server:
       port: 8081
    
     name : XiaoLi
    #对象
     person1:
       name1 : ${name}
      #XiaoLi
       age1 : 20
    
    #对象行内写法
     person2 : {name2: XiaoYue, age2: 30}
    
    #数组
     address1 :
       -Nanning
       -Liuzhou
    
      #数组行内写法
     address2 : [Nanning,Liuzhou]
    
    #纯量
     msg1 : 'hello \n world'
    #不会识别转义字符，导致原样输出
     msg2 : "hello \n world"
    #会识别转义字符

3）Controller

package com.lc.springboot_testbilbil;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.core.env.Environment;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class HelloController {
    
        @Value("${name}")
        private String Name;
    
        @Value("${person1.name1}")
        private String Name1;
    
        @Autowired
        private Environment env;
    
        @RequestMapping("/helloYML")
        public String hello(){
            System.out.println(Name);
            System.out.println(Name1);
            System.out.println("person2.name是"+env.getProperty("person2.name2"));
            System.out.println("person2.age是"+env.getProperty("person2.age2"));
            System.out.println("person1.name是"+env.getProperty("person1.name1"));
            System.out.println("person1.age是"+env.getProperty("person1.age1"));
            return "Hello World! 你好林月明!";
        }
    }

4)Application

5)运行结果

![eec11d1239ac46818a5dd176bdf8cd35.png][]

![8976bc5abe6247ab9b8915c4c7447dfd.png][] 注：刷新浏览器后，后台才会出现输出结果

**二、参考链接**

1、黑马程序员SpringBoot教程[https://www.bilibili.com/video/BV1Lq4y1J77x?p=5&vd\_source=841fee104972680a6cac4dbdbf144b50][https_www.bilibili.com_video_BV1Lq4y1J77x_p_5_vd_source_841fee104972680a6cac4dbdbf144b50]

2、报错解决

1）报错expected <block end>, but found BlockMappingStart......

解决方法：每个配置行前需要有空格!!!每个“：”两边需要有空格!!!数组中间加空格!!!

参考链接：

[https://www.cnblogs.com/chenkeyu/p/6858342.html][https_www.cnblogs.com_chenkeyu_p_6858342.html]

![ca7a12cf4e6d46ab846b3c8ecb52e43c.png][]

2）报错：Error starting ApplicationContext. To display the condition evaluation report re-run your application with 'debug' enabled.

解决方法：由于自己粗心，写错了引用字段，改正后就对了

其他参考链接：[https://blog.csdn.net/m0\_50762431/article/details/122143601][https_blog.csdn.net_m0_50762431_article_details_122143601]

![9faa4fb331fc46a19fe436a5e3267b52.png][]

3、Spring配置参考[https://docs.spring.io/spring-boot/docs/3.0.5/reference/html/configuration-metadata.html\#appendix.configuration-metadata.annotation-processor][https_docs.spring.io_spring-boot_docs_3.0.5_reference_html_configuration-metadata.html_appendix.configuration-metadata.annotation-processor]

[b861ba42112349ef84403162816f46bd.png]: https://img-blog.csdnimg.cn/b861ba42112349ef84403162816f46bd.png
[9c621ca12c3346219a573e7379dec228.png]: https://img-blog.csdnimg.cn/9c621ca12c3346219a573e7379dec228.png
[9c6c21408aa445118807db867d7ce7ab.png]: https://img-blog.csdnimg.cn/9c6c21408aa445118807db867d7ce7ab.png
[fe5301577afa48b6bee702814b1ec056.png]: https://img-blog.csdnimg.cn/fe5301577afa48b6bee702814b1ec056.png
[ccb5629581bd4953974f9ef550c62638.png]: https://img-blog.csdnimg.cn/ccb5629581bd4953974f9ef550c62638.png
[92d2e04ec3b94c0b8d62a1ce4b5616fb.png]: https://img-blog.csdnimg.cn/92d2e04ec3b94c0b8d62a1ce4b5616fb.png
[eec11d1239ac46818a5dd176bdf8cd35.png]: https://img-blog.csdnimg.cn/eec11d1239ac46818a5dd176bdf8cd35.png
[8976bc5abe6247ab9b8915c4c7447dfd.png]: https://img-blog.csdnimg.cn/8976bc5abe6247ab9b8915c4c7447dfd.png
[https_www.bilibili.com_video_BV1Lq4y1J77x_p_5_vd_source_841fee104972680a6cac4dbdbf144b50]: https://www.bilibili.com/video/BV1Lq4y1J77x?p=5&vd_source=841fee104972680a6cac4dbdbf144b50
[https_www.cnblogs.com_chenkeyu_p_6858342.html]: https://www.cnblogs.com/chenkeyu/p/6858342.html
[ca7a12cf4e6d46ab846b3c8ecb52e43c.png]: https://img-blog.csdnimg.cn/ca7a12cf4e6d46ab846b3c8ecb52e43c.png
[https_blog.csdn.net_m0_50762431_article_details_122143601]: https://blog.csdn.net/m0_50762431/article/details/122143601
[9faa4fb331fc46a19fe436a5e3267b52.png]: https://img-blog.csdnimg.cn/9faa4fb331fc46a19fe436a5e3267b52.png
[https_docs.spring.io_spring-boot_docs_3.0.5_reference_html_configuration-metadata.html_appendix.configuration-metadata.annotation-processor]: https://docs.spring.io/spring-boot/docs/3.0.5/reference/html/configuration-metadata.html#appendix.configuration-metadata.annotation-processor