【Java】编辑工具IntelliJ IDEA Community Edition写SpringBoot的HelloWorld
通过IDEA Community版本编辑器写SpringBoot的HelloWorld
前言
在开始之前，需要了解下
IntelliJ IDEA Ultimate（旗舰版）和IntelliJ IDEA Community Edition（社区版）的区别
费用
IntelliJ IDEA Ultimate（旗舰版）：收费
IntelliJ IDEA Community Edition（社区版）： 免费
开发
IntelliJ IDEA Ultimate（旗舰版）：类似于全自动步枪，异常流畅，很智能
IntelliJ IDEA Community Edition（社区版）： 类似于半自动步枪，异常流畅，对比Ultimate略显弱智
Spring Boot Hello Word
1.创建
点击菜单
选择File>New>Project...
弹出新窗体
输入名称：SpringBootHelloWord
设置项目路径：G:\1CodeTest\Java
编译模式：Maven
JDK版本：1.8
点击Create完成创建
会有个询问，我这里选择新的窗体，NewWindow
显示项目窗体
项目结构大致如下
2.新建 Controller和HelloWorld
在src》java右键》New》Java Class
输入类名 SpingBoot.Hello.Controller.HelloWorld后，按键盘 Enter完成新建
此时的项目目录结构如下图：
src》 main》 java 》SpingBoot.Hello.Controller》HelloWorld
打开HelloWorld.java，代码如下
java
package Controller;
@RestController
public class HelloWorld {
@RequestMapping("/hello") //路由指向
public String hello(){
LocalDateTime now=LocalDateTime.now();
return "Spring boot Hello World !当前时间："+ now.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
}
}如图
上图中，代码里的@RestController和@RequestMapping是红色的，需要我们手动引入
我们需要把光标放到@RestController上会出现个小灯泡，
点击小灯泡，会出现步骤3的窗体，
点击Add Maven dependency...
出现下图窗体
点击Search For Artfact
在输入框输入org.springframework.boot
找到org.springframework.boot:spring-boot-starter-web:2.6.13
点击Add完成添加引用
此时，你项目的pom.xml文件会出现下面代码
xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>2.6.13</version>
</dependency>这个就是我们刚才引入的包 
回到HelloWorld,java文件
此时@RestController和@RequestMapping依旧是红色的
但是，当我们鼠标移动到@RestController上面后提示 import class...,点击它
点击后他会生成如下代码
java
import org.springframework.web.bind.annotation.RestController;同样
我们鼠标移动到@RequestMapping上面后提示 import class...,点击它
java
import org.springframework.web.bind.annotation.RequestMapping;此时，在IDEA里面，@RestController和@RequestMapping会变成黄色，
如图
此时完整代码如下
java
package SpingBoot.Hello.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
@RestController
public class HelloWorld {
@RequestMapping("/hello")
public String hello(){
LocalDateTime now=LocalDateTime.now();
return "JJYCheng Spring boot Hello World !当前时间："+ now.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
}
}如下图
3.新建引导类
在src》java右键》New》Java Class
类名输入SpingBoot.Hello.HelloApplication后，按键盘 Enter完成新建
此时项目结构如下图
编写代码如下
java
/**
* 引导类-SpringBoot项目的入口
* **/
@SpringBootApplication
public class HelloApplication {
public static void main(String[] args){
SpringApplication.run(HelloApplication.class,args);
}
}如下图
@SpringBootApplication和SpringApplication是红色的，说明没有引入，
我们鼠标移动到上面，然后，点击import class...
处理后的完整代码如下
java
package SpingBoot.Hello;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
* 引导类-SpringBoot项目的入口
* **/
@SpringBootApplication
public class HelloApplication {
public static void main(String[] args){
SpringApplication.run(HelloApplication.class,args);
}
}如下图
4.运行
打开 HelloApplication.java文件，
点击左边三角运行按钮或者在空白区域右键然后点击Run HelloApplication.main()
运行成功后，右上角显示效果是这样的，如下图：
控制台显示如下图：
控制台文本
bash
"C:\Program Files\Java\jdk1.8.0_261\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2024.1.4\lib\idea_rt.jar=14932:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2024.1.4\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_261\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_261\jre\lib\rt.jar;G:\1CodeTest\Java\SpringBootHelloWord\target\classes;G:\1CodeTest\Java\Maven\Repository\org\springframework\boot\spring-boot-starter-web\2.6.13\spring-boot-starter-web-2.6.13.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\boot\spring-boot-starter\2.6.13\spring-boot-starter-2.6.13.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\boot\spring-boot\2.6.13\spring-boot-2.6.13.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\boot\spring-boot-autoconfigure\2.6.13\spring-boot-autoconfigure-2.6.13.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\boot\spring-boot-starter-logging\2.6.13\spring-boot-starter-logging-2.6.13.jar;G:\1CodeTest\Java\Maven\Repository\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;G:\1CodeTest\Java\Maven\Repository\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;G:\1CodeTest\Java\Maven\Repository\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar;G:\1CodeTest\Java\Maven\Repository\org\apache\logging\log4j\log4j-to-slf4j\2.17.2\log4j-to-slf4j-2.17.2.jar;G:\1CodeTest\Java\Maven\Repository\org\apache\logging\log4j\log4j-api\2.17.2\log4j-api-2.17.2.jar;G:\1CodeTest\Java\Maven\Repository\org\slf4j\jul-to-slf4j\1.7.36\jul-to-slf4j-1.7.36.jar;G:\1CodeTest\Java\Maven\Repository\jakarta\annotation\jakarta.annotation-api\1.3.5\jakarta.annotation-api-1.3.5.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\spring-core\5.3.23\spring-core-5.3.23.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\spring-jcl\5.3.23\spring-jcl-5.3.23.jar;G:\1CodeTest\Java\Maven\Repository\org\yaml\snakeyaml\1.29\snakeyaml-1.29.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\boot\spring-boot-starter-json\2.6.13\spring-boot-starter-json-2.6.13.jar;G:\1CodeTest\Java\Maven\Repository\com\fasterxml\jackson\core\jackson-databind\2.13.4.2\jackson-databind-2.13.4.2.jar;G:\1CodeTest\Java\Maven\Repository\com\fasterxml\jackson\core\jackson-annotations\2.13.4\jackson-annotations-2.13.4.jar;G:\1CodeTest\Java\Maven\Repository\com\fasterxml\jackson\core\jackson-core\2.13.4\jackson-core-2.13.4.jar;G:\1CodeTest\Java\Maven\Repository\com\fasterxml\jackson\datatype\jackson-datatype-jdk8\2.13.4\jackson-datatype-jdk8-2.13.4.jar;G:\1CodeTest\Java\Maven\Repository\com\fasterxml\jackson\datatype\jackson-datatype-jsr310\2.13.4\jackson-datatype-jsr310-2.13.4.jar;G:\1CodeTest\Java\Maven\Repository\com\fasterxml\jackson\module\jackson-module-parameter-names\2.13.4\jackson-module-parameter-names-2.13.4.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\boot\spring-boot-starter-tomcat\2.6.13\spring-boot-starter-tomcat-2.6.13.jar;G:\1CodeTest\Java\Maven\Repository\org\apache\tomcat\embed\tomcat-embed-core\9.0.68\tomcat-embed-core-9.0.68.jar;G:\1CodeTest\Java\Maven\Repository\org\apache\tomcat\embed\tomcat-embed-el\9.0.68\tomcat-embed-el-9.0.68.jar;G:\1CodeTest\Java\Maven\Repository\org\apache\tomcat\embed\tomcat-embed-websocket\9.0.68\tomcat-embed-websocket-9.0.68.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\spring-web\5.3.23\spring-web-5.3.23.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\spring-beans\5.3.23\spring-beans-5.3.23.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\spring-webmvc\5.3.23\spring-webmvc-5.3.23.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\spring-aop\5.3.23\spring-aop-5.3.23.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\spring-context\5.3.23\spring-context-5.3.23.jar;G:\1CodeTest\Java\Maven\Repository\org\springframework\spring-expression\5.3.23\spring-expression-5.3.23.jar" SpingBoot.Hello.HelloApplication
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.6.13)
2024-08-04 11:31:51.208 INFO 10236 --- [ main] SpingBoot.Hello.HelloApplication : Starting HelloApplication using Java 1.8.0_261 on DESKTOP-2T12I06 with PID 10236 (G:\1CodeTest\Java\SpringBootHelloWord\target\classes started by cheng in G:\1CodeTest\Java\SpringBootHelloWord)
2024-08-04 11:31:51.213 INFO 10236 --- [ main] SpingBoot.Hello.HelloApplication : No active profile set, falling back to 1 default profile: "default"
2024-08-04 11:31:53.017 INFO 10236 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2024-08-04 11:31:53.035 INFO 10236 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2024-08-04 11:31:53.035 INFO 10236 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.68]
2024-08-04 11:31:53.193 INFO 10236 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2024-08-04 11:31:53.193 INFO 10236 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1916 ms
2024-08-04 11:31:53.609 INFO 10236 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2024-08-04 11:31:53.618 INFO 10236 --- [ main] SpingBoot.Hello.HelloApplication : Started HelloApplication in 2.955 seconds (JVM running for 3.484)打开浏览器访问
打开浏览器输入：http://localhost:8080/hello
为什么要带 hello呢？
是因为，
我们在HelloWorld.java文件设置了路由规则@RequestMapping("/hello")，
他里面的/hello就是http://localhost:8080后缀/hello的原因。
