Spring Boot

Posted 2021-11-06 cnwuhao

spring boot 它的设计目的就是为例简化开发，开启了各种自动装配，你不想写各种配置文件，引入相关的依赖就能迅速搭建起一个web工程。它采用的是建立生产就绪的应用程序观点，优先于配置的惯例。

建构工程需要15分钟、jdk 1.8+、maven 3.0+。

打开Idea-> new Project ->Spring Initializr ->填写group、artifact ->钩上web(开启web功能）->点下一步。工具自动创建了一个项目，SpringbootApplication类为程序的入口。

pom.xml依赖文件如下

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 
 3 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4 
 5     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 6 
 7     <modelVersion>4.0.0</modelVersion>
 8 
 9  
10 
11     <groupId>com.forezp</groupId>
12 
13     <artifactId>springboot-first-application</artifactId>
14 
15     <version>0.0.1-SNAPSHOT</version>
16 
17     <packaging>jar</packaging>
18 
19  
20 
21     <name>springboot-first-application</name>
22 
23     <description>Demo project for Spring Boot</description>
24 
25  
26 
27     <parent>
28 
29         <groupId>org.springframework.boot</groupId>
30 
31         <artifactId>spring-boot-starter-parent</artifactId>
32 
33         <version>1.5.2.RELEASE</version>
34 
35         <relativePath/> <!-- lookup parent from repository -->
36 
37     </parent>
38 
39  
40 
41     <properties>
42 
43         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
44 
45         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
46 
47         <java.version>1.8</java.version>
48 
49     </properties>
50 
51  
52 
53     <dependencies>
54 
55         <dependency>
56 
57             <groupId>org.springframework.boot</groupId>
58 
59             <artifactId>spring-boot-starter-web</artifactId>
60 
61         </dependency>
62 
63  
64 
65         <dependency>
66 
67             <groupId>org.springframework.boot</groupId>
68 
69             <artifactId>spring-boot-starter-test</artifactId>
70 
71             <scope>test</scope>
72 
73         </dependency>
74 
75     </dependencies>
76 
77  
78 
79     <build>
80 
81         <plugins>
82 
83             <plugin>
84 
85                 <groupId>org.springframework.boot</groupId>
86 
87                 <artifactId>spring-boot-maven-plugin</artifactId>
88 
89             </plugin>
90 
91         </plugins>
92 
93     </build>
94 
95  
96 
97  
98 
99 </project>

其中spring-boot-starter-web不仅包含spring-boot-starter,还自动开启了web功能。

建个controller

 1 import org.springframework.web.bind.annotation.RestController;
 2 
 3 import org.springframework.web.bind.annotation.RequestMapping;
 4 
 5  
 6 
 7 @RestController
 8 
 9 public class HelloController {
10 
11  
12 
13     @RequestMapping("/")
14 
15     public String index() {
16 
17         return "Greetings from Spring Boot!";
18 
19     }
20 
21  
22 
23 }

启动SpringbootFirstApplication的main方法，输入

curl -S localhost:8080/hi

启动springboot 方式

cd到项目主目录

mvn clean 
mvn package
mvn spring-boot: run

 

或者 cd 到target目录，java -jar 项目.jar

来看看springboot在启动的时候为我们注入了哪些bean

在程序入口加入：

@SpringBootApplication

public class SpringbootFirstApplication {

 

    public static void main(String[] args) {

        SpringApplication.run(SpringbootFirstApplication.class, args);

    }

 

    @Bean

    public CommandLineRunner commandLineRunner(ApplicationContext ctx) {

        return args -> {

 

            System.out.println("Let‘s inspect the beans provided by Spring Boot:");

 

            String[] beanNames = ctx.getBeanDefinitionNames();

            Arrays.sort(beanNames);

            for (String beanName : beanNames) {

                System.out.println(beanName);

            }

 

        };

    }

 

}

 

程序输出：

Let’s inspect the beans provided by Spring Boot: 
basicErrorController 
beanNameHandlerMapping 
beanNameViewResolver 
characterEncodingFilter 
commandLineRunner 
conventionErrorViewResolver 
defaultServletHandlerMapping 
defaultViewResolver 
dispatcherServlet 
dispatcherServletRegistration 
duplicateServerPropertiesDetector 
embeddedServletContainerCustomizerBeanPostProcessor 
error 
errorAttributes 
errorPageCustomizer 
errorPageRegistrarBeanPostProcessor

…. 
….

在程序启动的时候，springboot自动诸如注入了40-50个bean.

单元测试

通过@RunWith() @SpringBootTest开启注解：

@RunWith(SpringRunner.class)

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)

public class HelloControllerIT {

 

    @LocalServerPort

    private int port;

 

    private URL base;

 

    @Autowired

    private TestRestTemplate template;

 

    @Before

    public void setUp() throws Exception {

        this.base = new URL("http://localhost:" + port + "/");

    }

 

    @Test

    public void getHello() throws Exception {

        ResponseEntity<String> response = template.getForEntity(base.toString(),

                String.class);

        assertThat(response.getBody(), equalTo("Greetings from Spring Boot!"));

    }

}

运行它会先开启sprigboot工程，然后再测试，测试通过 ^.^