springboot 01---------环境搭建，基础配置讲解

spring boot是一个简化spring开发的框架，核心在于约定大于配置，去除繁琐的配置。简单的说就是spring boot整合了很多优秀的框架，不用我们去手写一大推的xml文件，它在后台帮我做了这些配置

下面演示如何在IntellJ上面进行spring boot开发

1.new Module

2.配置mvn信息

3.添加应用，这里我们选择web应用

这些操作完成之后，ide会帮我们构建一个基于mvn的spring boot project,查看下pom.xml

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

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

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

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

</project>

1.spring-boot-starter-parent 是一个特殊的starter，它用来提供相关的Maven默认依赖。使用它之后，常用的包依赖可以省去version标签。

2.spring-boot-starter-web   提供mvc功能

package com.example.springboot;

import com.examples.model.Animal;
import com.examples.model.Dog;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@ComponentScan(basePackages = "com.examples")
@RequestMapping("springboot")
@RestController
public class SpringbootApplication {

    @Autowired
    private Dog dog;

    @Autowired
    private Animal animal;

    @RequestMapping("/Hello")
    public String Hello(){
        return dog.toString()+"\r\n"+animal.toString();
    }

    @Bean("animal")
    public Animal getAnimal(){
        return new Animal();
    }


    public static void main(String[] args) {

        ConfigurableApplicationContext context =  SpringApplication.run(SpringbootApplication.class, args);
        Dog dog = (Dog)context.getBean("dog");
        Animal animal = (Animal)context.getBean("animal");
        System.out.println(dog);
        System.out.println(animal);
    }

}


package com.examples.model;

import org.springframework.beans.factory.annotation.Value;

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/7/19
 */
public class Animal {

    @Value("${animal.gender}")
    public Boolean gender;

    @Override
    public String toString() {
        return "Animal{" +
                "gender=" + gender +
                '}';
    }
}


package com.examples.model;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/7/19
 */
@Component
@ConfigurationProperties(prefix="dog")
public class Dog {

    private String name;

    public void setAge(Integer age) {
        this.age = age;
    }

    private Integer age;

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Dog{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}


//application.yml
server:
  port: 8088

dog:
  name: 哈士奇
  age: 12

animal:
  gender: false


或者application.properties

server.port=8088

dog.name = "wangcai"
dog.age = 10
#dog.map.m1 = "hello"
#dog.map.m2 = "world"

说明：

@SpringBootApplication = @SpringBootConfiguration + @EnableAutoConfiguration + @ComponentScan

@SpringBootConfiguration： extends @Configuration  表明当前类是个spring的配置类，可以在这里面注入bean等。

@ComponentScan： 扫描包下面的@Controller，@Service，@Respority，@Componet等；默认情况下是扫描当前类所在路径，以及所在子路径。

@EnableAutoConfiguration： 启动自动的配置，比如你添加了spring-boot-starter-web，spring boot会自动帮你配置webmvc，tomcat等需要的配置。

@ConfigurationProperties配合 @Component 可以获取配置文件里面的信息，实现属性注入