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;}}

5.3、测试

那么在浏览器访问地址：http://127.0.0.1:8080/demo/getDemo 返回如下数据：