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