SpringBoot-1快速入门初始化工程
简化Spring应用的初始搭建以及开发过程，Spring已经很简化了，再进一步简化下
1. 开始配置一个项目 入门案例
1.1 初始化项目
使用IDEA创建一个SpringBoot工程，new project这边选择到Spring Initialzr，里面的各项选项注意和这里对应到
这里注意一下SpringBoot的版本，3.x需要jdk17的支持，所以这里实际降级一下选到jdk8去
至此工程加载完毕，删掉除了.idea，src，pom.xml的其他文件，保留到下面的这些
项目结构整体如下
1.2 创建controller
创建如下的Java类，并把这个RestController和RequestMapping给写上
/Users/curious/Desktop/Engineering/java/demo/src/main/java/cn/edu/bupt/controller/SwitchBoardController.java
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| package cn.edu.bupt.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/switchboard")
public class SwitchBoardController {
}
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进一步完善一个getById功能，这样写好后SpringBoot程序就已经开发完了，Tomcat服务器那些都不需要了
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| package cn.edu.bupt.controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/switchboard")
public class SwitchBoardController {
@GetMapping("/{id}")
public String getById(@PathVariable Integer id) {
System.out.println("id: " + id);
return "Hello, SpringBoot!";
}
}
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右键点击src/main/java/cn/edu/bupt/DemoApplication.java，选择Run Application，直接启动起来了
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| . ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.7.8)
|
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| 2023-02-18 17:05:28.221 INFO 18715 --- [ main] cn.edu.bupt.DemoApplication : Starting DemoApplication using Java 1.8.0_312 on CuriousdeMacBook-Pro.local with PID 18715 (/Users/curious/Desktop/Engineering/java/demo/target/classes started by curious in /Users/curious/Desktop/Engineering/java/demo)
2023-02-18 17:05:28.222 INFO 18715 --- [ main] cn.edu.bupt.DemoApplication : No active profile set, falling back to 1 default profile: "default"
2023-02-18 17:05:28.569 INFO 18715 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2023-02-18 17:05:28.572 INFO 18715 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2023-02-18 17:05:28.572 INFO 18715 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.71]
2023-02-18 17:05:28.598 INFO 18715 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2023-02-18 17:05:28.599 INFO 18715 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 356 ms
2023-02-18 17:05:28.714 INFO 18715 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2023-02-18 17:05:28.718 INFO 18715 --- [ main] cn.edu.bupt.DemoApplication : Started DemoApplication in 0.661 seconds (JVM running for 0.901)
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| curl --location --request GET 'http://localhost:8080/switchboard/1'
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1.3 原理分析
不是pom.xml干的活就是DemoApplication干的活
N. 报错解决
N.1 java: 错误: 无效的源发行版：17
报错源于点击run application的时候，解决办法是Module这里面也要跟着改
这样还是没有解决，最后发现是SpringBoot3.x版本需要jdk17作为支撑，这里选用比较简单的方法，重新创建一个项目，降低SpringBoot版本；