SpringBoot2 ---- write a HelloWorld

1, What is SpringBoot?

Spring Boot is a new framework provided by pivot team. It is designed to simplify the initial construction and development process of new spring applications. The framework uses a specific way to configure, so that developers no longer need to define templated configurations.

2, Characteristics

Create a stand-alone Spring application
Embedded Tomcat, no need to deploy WAR file
Simplify Maven configuration
Auto configure Spring
Provide production ready functions such as indicators, health checks and external configurations
There is absolutely no code generation and no configuration requirements for XML

3, Write Spring Boot's Hello World

1. Environment for installing Spring Boot

Create a Maven project (I use IDEA2019.3.x), or directly create a Spring Initializr project. You can directly write a helloworld file. You can view:
SpringBoot is created directly without configuring the pom.xml path

Install the SpringBoot environment using the pom.xml file

pom.xml file:

<packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.4.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Previously, when learning spring MVC, our packaging method was

<packaging>war</packaging>

When writing a SpringBoot project, you can change it to jar

<packaging>jar</packaging>

In this way, it is convenient to package and send to others after the completion of later projects, so there is no need to configure this environment.

After the environment required in the pom.xml package is written, wait for the download. After the download, the environment configuration is completed.

2. You are now ready to create a java file to write

SpringBoot is a further simplification of other Spring design patterns. There is no need to configure mapper.xml or a separate tomcat. Just use one controller to execute.

The properties file in the resources is used to configure the port number of tomcat and some other variable quantities.

In the HelloController.java file, it is the same as the previous spring MVC. Use @ RequestMapping to set a path for the Hello method

HelloController.java

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";
    }
}

MySpringBoot.java

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

/**
 * Main program class
 * @SpringBootApplication:This is a SpringBoot application
 */

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

3. Run

Run the MySpringBootTest file directly