1. 在pom.xml中添加依赖

步骤如下：

添加springboot的parent依赖
添加springboot的starter-web依赖。还有很多针对其它场景的starter启动器
修改mysql的版本号
添加springboot的打包插件

内容如下：

<?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.hh</groupId>
    <artifactId>springbootTest</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.5</version>
    </parent>

    <properties>
        <!-- 修改mysql的版本号 -->
        <mysql.version>8.0.25</mysql.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
		<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-shade-plugin</artifactId>
				<version>${shade.plugin.version}</version>
				<dependencies>
					<dependency>
						<groupId>org.springframework.boot</groupId>
						<artifactId>spring-boot-maven-plugin</artifactId>
						<version>${spring.boot.version}</version>
					</dependency>
				</dependencies>
				<executions>
					<execution>
						<phase>package</phase>
						<goals>
							<goal>shade</goal>
						</goals>
						<configuration>
							<artifactSet>
								<excludes>
									<exclude></exclude>
								</excludes>
							</artifactSet>
							<filters>
								<filter>
									<artifact>*:*</artifact>
									<excludes>
										<exclude>META-INF/*.SF</exclude>
										<exclude>META-INF/*.RSA</exclude>
										<exclude>META-INF/*.DSA</exclude>
										<!-- 解决java -classpath ... class运行错误：ERROR StatusLogger Unrecognized format specifier -->
										<exclude>**/Log4j2Plugins.dat</exclude>
									</excludes>
								</filter>
							</filters>
							<transformers>
								<transformer
										implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
									<resource>META-INF/spring.handlers</resource>
									<resource>reference.conf</resource>
								</transformer>
								<transformer
										implementation="org.springframework.boot.maven.PropertiesMergingResourceTransformer">
									<resource>META-INF/spring.factories</resource>
								</transformer>
								<transformer
										implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
									<resource>META-INF/spring.schemas</resource>
								</transformer>
								<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
									<mainClass></mainClass>
									<!-- 解决: WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact performance -->
									<manifestEntries>
										<Multi-Release>true</Multi-Release>
									</manifestEntries>
								</transformer>
							</transformers>
						</configuration>
					</execution>
				</executions>
			</plugin>
        </plugins>
    </build>

</project>

2. 编辑resources/application.properties

该配置文件的名称是约定好的。修改tomcat的端口号，如下所示：

# 修改tomcat的端口号
server.port = 8088

配置文件的值会绑定对应的类上，类会在IOC容器中创建对象

也可以定义配置文件application.yaml。会和application.properties进行配置合并，但application.properties的优先级更高

3. 编写springboot的主程序

注解说明：

@SpringBootApplication：表明这是一个springboot应用。会自动扫描同一目录下的其它所有文件夹和文件

如下所示：

package com.hh.springbootTest;

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

// springboot的程序入口，表明这是一个springboot应用
// 默认会自动扫描同一目录下的其它所有文件夹和文件
@SpringBootApplication
public class MyApplication {

    public static void main(String[] args) {

        SpringApplication.run(MyApplication.class, args);

    }
}

4. 编写Controller程序

注解说明：

@Controller：表明这是一个控制器
@ResponseBody：表示请求该地址会有数据返回
@RequestMapping：表示请求的具体地址
@RestController：等同于@ResponseBody + @Controller

如下所示：

package com.hh.springbootTest.myController;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

// @ResponseBody       // 也可以放在函数上面，单独修饰函数
// @Controller

@RestController     // 等同于：@ResponseBody + @Controller
public class HelloController {

    @RequestMapping("/hello")
    public String helloHandle() {
        return "hello springboot";
    }

}