SpringBoot2.0.2 Application调用的三种方式

时间：2021-08-01 07:54:25

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

 

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