纯手工创建SpringBoot项目——HelloWorld

Maven 使用约定优于配置的原则

目录	用途
${basedir}	存放pom.xml和所有的子目录
${basedir}/src/main/java	项目的java源代码
${basedir}/src/main/resources	项目的资源，比如说property文件，springmvc.xml
${basedir}/src/test/java	项目的测试类，比如说Junit代码
${basedir}/src/test/resources	测试用的资源
${basedir}/src/main/webapp/WEB-INF	web应用文件目录，web项目的信息，比如存放web.xml、本地图片、jsp视图页面
${basedir}/target	打包输出目录
${basedir}/target/classes	编译输出目录
${basedir}/target/test-classes	测试编译输出目录
Test.java	Maven只会自动运行符合该命名规则的测试类
~/.m2/repository	Maven默认的本地仓库目录位置

1.创建maven工程

// 创建项目根据目录
~/Desktop$ mkdir MySpringboot

// 按照上面maven的约定创建目录
~/Desktop$ mkdir -p MySpringboot/src/main/java
~/Desktop$ mkdir -p MySpringboot/src/main/resources
~/Desktop$ mkdir -p MySpringboot/src/test/java
~/Desktop$ mkdir -p MySpringboot/src/test/resources

// 在根目录下创建pom.xml文件
~/Desktop$ touch MySpringboot/pom.xml

// 创建好的maven项目目录结构
~/Desktop$ tree MySpringboot
MySpringboot
├── pom.xml
└── src
    ├── main
    │   ├── java
    │   └── resources
    └── test
        ├── java
        └── resources

7 directories, 1 file

2.导入spring boot相关依赖

在pom.xml加入如下配置：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.wong</groupId>
    <!--与项目名称一致-->
    <artifactId>MySpringboot</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.5.RELEASE</version>
        <relativePath/>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
</project>

spring-boot-starter-web这个场景启动器会把与web开发相关的依赖导进项目，更多场景启动器请参考：springboot场景启动器

3.编写主程序：启动Spring Boot应用

创建包名com.wong（实际上就是目录）:

~/Desktop/MySpringboot$ mkdir -p src/main/java/com/wong

在包com.wong创建主程序MainApplication.java:

package com.wong;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
* @SpringBootApplication用于标注主程序
*/
@SpringBootApplication
public class MainApplication{

        public static void main(String[] args){
        		// 启动Spring应用
                SpringApplication.run(MainApplication.class,args);
        }
}

4.编写业务相关的Controller

创建多一个包，用来存放业务控制器：

~/Desktop/MySpringboot$ mkdir -p src/main/java/com/wong/controller

创建控制器HelloWorldController.java:

package com.wong.controller;

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

@RestController
@RequestMapping("world")
public class HelloWorldController{

        @GetMapping("hi")
        public String index(){
                return "Hello World!";
        }
}

5.测试

使用mvn spring-boot:run命令运行程序：

~/Desktop/MySpringboot$ mvn spring-boot:run
[INFO] Scanning for projects...
...
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.5.RELEASE)

2020-03-24 22:13:45.941  INFO 20580 --- [           main] com.wong.MainApplication                 : Starting MainApplication on kyun-HP-348-G3 with PID 20580 (/home/kyun/Desktop/MySpringboot/target/classes started by kyun in /home/kyun/Desktop/MySpringboot)
2020-03-24 22:13:45.944  INFO 20580 --- [           main] com.wong.MainApplication                 : No active profile set, falling back to default profiles: default
2020-03-24 22:13:46.662  INFO 20580 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2020-03-24 22:13:46.670  INFO 20580 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-03-24 22:13:46.671  INFO 20580 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.31]
2020-03-24 22:13:46.716  INFO 20580 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-03-24 22:13:46.716  INFO 20580 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 720 ms
2020-03-24 22:13:46.852  INFO 20580 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-03-24 22:13:46.967  INFO 20580 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2020-03-24 22:13:46.969  INFO 20580 --- [           main] com.wong.MainApplication                 : Started MainApplication in 1.298 seconds (JVM running for 1.604)

浏览器输入http://localhost:8080/world/hi：
　在这里插入图片描述

7.简化部署

完全可以不用打war包，再发布到Tomcat容器里。可以直接打出jar包，然后直接用java -jar <name>.jar命令来运行。
首先，要在pom.xml加入以下插件：

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

然后执行以下打包命令：

~/Desktop/MySpringboot$ mvn package spring-boot:repackage

打出来的包在target目录下：

~/Desktop/MySpringboot$ cd target
~/Desktop/MySpringboot/target$ ls
classes                 maven-status
generated-sources       MySpringboot-1.0-SNAPSHOT.jar
generated-test-sources  MySpringboot-1.0-SNAPSHOT.jar.original
maven-archiver          test-classes
~/Desktop/MySpringboot/target$ java -jar MySpringboot-1.0-SNAPSHOT.jar
...

以上就是创建SpringBoot项目的所有内容。

WongKyunban

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