Spring Boot 学习笔记

学习代码第一步：如何写 Hello world ？

1、新建项目

新建一个 Maven Java 工程，在 pom.xml 文件中添加 Spring Boot Maven 依赖：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.1.6</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>

2、创建启动类

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

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

3、创建HelloController

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

@RestController
public class HelloController {

    @RequestMapping("/")
    public String hello(){
        return "Hello world!!";
    }
}

4、启动

运行App的Main函数，之后打开浏览器输入地址：http://127.0.0.1:8080/ 就可以看到 Hello world!了。

5、返回JSON数据

5.1、编写一个实体类Demo

package org.example.bean;

public class Demo {
    private long id ;
    private  String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

}

5.2、编写 DemoController

在 DemoController 加上@RestController 和@RequestMapping 注解；

package org.example.web;

import org.example.bean.Demo;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController()
@RequestMapping("/demo")
public class DemoController {

    @RequestMapping("/getDemo")
    public Demo getDemo(){
        Demo demo = new Demo();
        demo.setId(1L);
        demo.setName("风萧萧1999");
        return demo;
    }

}