2、SpringBoot项目解析

• parent
• starter
• 引导类
• 内嵌tomcat

parent

GAV可以只写GA，不写version

spring-boot-dependencies
spring-boot-starter-parent 定义了依赖管理，减少依赖冲突

starter

spring-boot-starter-web 进行依赖传递，减少依赖配置

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
        <version>2.7.7</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-json</artifactId>
        <version>2.7.7</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
        <version>2.7.7</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>5.3.24</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.3.24</version>
        <scope>compile</scope>
    </dependency>
</dependencies>

引导类

1. SpringBoot工程提供引导类用来启动程序
2. SpringBoot工程启动后创建并初始化Spring容器

package com.example.demo;

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

@SpringBootApplication
public class Application {

	public static void main(String[] args) {
		ConfigurableApplicationContext ctx = SpringApplication.run(Application.class, args);
	}

}

内嵌tomcat

排除tomcat后，SpringBoot工程运行后就退出了

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </exclusion>
    </exclusions>
</dependency>

SpringBoot工程使用jetty作为内嵌容器

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jetty</artifactId>
    </dependency>
</dependencies>

内置服务器

• tomcat 默认，应用面广
• jetty 比tomcat更轻量级
• undertow 性能最好