SpringBoot2.0.2 Application调用的三种方式

一、注解

          @SpringBootApplication

           点开查看源码是由多个注解合成的注解，其中主要的注解有：
            @SpringBootConfiguration
            @EnableAutoConfiguration
            @ComponentScan


           三个关键的注解：
             @ComponentScan 自动扫描加载进来的包，-----------可以扫描自动加载的bean
            @EnableAutoConfiguration 启动自动配置
           @SpringBootConfiguration 继承了@Configuration，所以可以使用@Configuration内容
          @Configuration是spring提供的注解，@SpringBootConfiguration是springboot提供的注解。效果几乎一样，用哪个看自己的习惯。
二、pom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.springboot</groupId>
    <artifactId>quick_start</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>quick_start</name>
    <url>http://maven.apache.org</url>
    <description>Demo project for Spring Boot</description>

    <!--<parent>-->
    <!--<groupId>org.springframework.boot</groupId>-->
    <!--<artifactId>spring-boot-starter-parent</artifactId>-->
    <!--<version>2.0.2.RELEASE</version>-->
    <!--<relativePath/> &lt;!&ndash; lookup parent from repository &ndash;&gt;-->
    <!--</parent>-->

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <!--不使用parent方式进行依赖,需要scope和type设置-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>2.0.2.RELEASE</version>
            <scope>import</scope>
            <type>pom</type>
        </dependency>


        <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>

三、Application调用的三种方法

     方法一：静态方法调用

package com.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;

/******************************
 * @Author : liuyang
 * @ClassName : QuickStartApplication
 * @Date : 2018 五月  20
 * @Time : 01:05:59
 * @Type : SpringBoot
 * @Version : 1.0
 * @Return :
 * @Description :
 *******************************/

@ComponentScan
@EnableAutoConfiguration
public class QuickStartApplication {

    @Bean
    public Runnable createRunnable() {

        return () -> {
            System.out.println("Spring Boot is Run");
        };

    }

    public static void main(String[] args) {
        ConfigurableApplicationContext applicationContext = SpringApplication.run(QuickStartApplication.class,args);
        applicationContext.getBean(Runnable.class).run();
        System.out.println(applicationContext.getBean(User.class));
    }
}

        方法二：非态方法调用，可以拥有多个资源入口

package com.springboot;

import com.srpingboot.nostatic.ApplicationDemo;
import org.springframework.boot.SpringApplication;
import org.springframework.context.ConfigurableApplicationContext;

import java.util.HashSet;
import java.util.Set;

/**
 * Created by
 *
 * @author: liuya
 * @Date: 2018/5/20 2:18
 * @Description: quick_start
 * <p>
 * 指定多个源,调用非springApplication方法
 */

public class ManyApplication {

    public static void main(String[] args) {

        // new实例对象调用
       SpringApplication application = new SpringApplication();

       // 可以指定多个源的方式
       Set<String> sets = new HashSet<>();
       sets.add(ApplicationDemo.class.getName());
       sets.add(User.class.getName());            
       application.setSources(sets);

       

        ConfigurableApplicationContext applicationContext = application.run(args);
        applicationContext.getBean(Runnable.class).run();
        System.out.println(applicationContext.getBean(User.class));
    }


}

          建立ApplicationDemo

package com.srpingboot.nostatic;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;

/**
 * Created by
 *
 * @author: liuya
 * @Date: 2018/5/20 2:23
 * @Description: quick_start
 */
@ComponentScan
@EnableAutoConfiguration
public class ApplicationDemo {

    @Bean
    public Runnable createRunnable() {

        return () -> {
            System.out.println("Spring Boot is Run");
        };

    }
}

       方法三 ：构造函数指定方式

package com.springboot;

import com.srpingboot.nostatic.ApplicationDemo;
import org.springframework.boot.SpringApplication;
import org.springframework.context.ConfigurableApplicationContext;

import java.util.HashSet;
import java.util.Set;

/**
 * Created by
 *
 * @author: liuya
 * @Date: 2018/5/20 2:18
 * @Description: quick_start
 * <p>
 * 指定多个源,调用非springApplication方法
 */


public class ManyApplication {

    public static void main(String[] args) {

        //构造函数指定方式
        SpringApplication application = new SpringApplication(ApplicationDemo.class,User.class);



        ConfigurableApplicationContext applicationContext = application.run(args);
        applicationContext.getBean(Runnable.class).run();
        System.out.println(applicationContext.getBean(User.class));
    }


}

        

 源码地址：

             https://github.com/liushaoye/quick_start