SpringBoot2.0.2 Application调用的三种方式

Posted 2020-11-07 北极的大企鹅

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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

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 3          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 4     <modelVersion>4.0.0</modelVersion>
 5 
 6     <groupId>com.springboot</groupId>
 7     <artifactId>quick_start</artifactId>
 8     <version>0.0.1-SNAPSHOT</version>
 9     <packaging>jar</packaging>
10 
11     <name>quick_start</name>
12     <url>http://maven.apache.org</url>
13     <description>Demo project for Spring Boot</description>
14 
15     <!--<parent>-->
16     <!--<groupId>org.springframework.boot</groupId>-->
17     <!--<artifactId>spring-boot-starter-parent</artifactId>-->
18     <!--<version>2.0.2.RELEASE</version>-->
19     <!--<relativePath/> &lt;!&ndash; lookup parent from repository &ndash;&gt;-->
20     <!--</parent>-->
21 
22     <properties>
23         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
24         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
25         <maven.compiler.source>1.8</maven.compiler.source>
26         <maven.compiler.target>1.8</maven.compiler.target>
27         <java.version>1.8</java.version>
28     </properties>
29 
30     <dependencies>
31         <!--不使用parent方式进行依赖,需要scope和type设置-->
32         <dependency>
33             <groupId>org.springframework.boot</groupId>
34             <artifactId>spring-boot-dependencies</artifactId>
35             <version>2.0.2.RELEASE</version>
36             <scope>import</scope>
37             <type>pom</type>
38         </dependency>
39 
40 
41         <dependency>
42             <groupId>org.springframework.boot</groupId>
43             <artifactId>spring-boot-starter-web</artifactId>
44         </dependency>
45 
46         <dependency>
47             <groupId>org.springframework.boot</groupId>
48             <artifactId>spring-boot-starter-test</artifactId>
49             <scope>test</scope>
50         </dependency>
51     </dependencies>
52 
53     <build>
54         <plugins>
55             <plugin>
56                 <groupId>org.springframework.boot</groupId>
57                 <artifactId>spring-boot-maven-plugin</artifactId>
58             </plugin>
59         </plugins>
60     </build>
61 
62 
63 </project>

View Code

三、Application调用的三种方法

方法一：静态方法调用

 1 package com.springboot;
 2 
 3 import org.springframework.boot.SpringApplication;
 4 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 5 import org.springframework.boot.autoconfigure.SpringBootApplication;
 6 import org.springframework.context.ConfigurableApplicationContext;
 7 import org.springframework.context.annotation.Bean;
 8 import org.springframework.context.annotation.ComponentScan;
 9 
10 /******************************
11  * @Author : liuyang
12  * @ClassName : QuickStartApplication
13  * @Date : 2018 五月  20
14  * @Time : 01:05:59
15  * @Type : SpringBoot
16  * @Version : 1.0
17  * @Return :
18  * @Description :
19  *******************************/
20 
21 @ComponentScan
22 @EnableAutoConfiguration
23 public class QuickStartApplication {
24 
25     @Bean
26     public Runnable createRunnable() {
27 
28         return () -> {
29             System.out.println("Spring Boot is Run");
30         };
31 
32     }
33 
34     public static void main(String[] args) {
35         ConfigurableApplicationContext applicationContext = SpringApplication.run(QuickStartApplication.class,args);
36         applicationContext.getBean(Runnable.class).run();
37         System.out.println(applicationContext.getBean(User.class));
38     }
39 }

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方法二：非态方法调用，可以拥有多个资源入口

 1 package com.springboot;
 2 
 3 import com.srpingboot.nostatic.ApplicationDemo;
 4 import org.springframework.boot.SpringApplication;
 5 import org.springframework.context.ConfigurableApplicationContext;
 6 
 7 import java.util.HashSet;
 8 import java.util.Set;
 9 
10 /**
11  * Created by
12  *
13  * @author: liuya
14  * @Date: 2018/5/20 2:18
15  * @Description: quick_start
16  * <p>
17  * 指定多个源,调用非springApplication方法
18  */
19 
20 public class ManyApplication {
21 
22     public static void main(String[] args) {
23 
24         // new实例对象调用
25        SpringApplication application = new SpringApplication();
26 
27        // 可以指定多个源的方式
28        Set<String> sets = new HashSet<>();
29        sets.add(ApplicationDemo.class.getName());
30        sets.add(User.class.getName());            
31        application.setSources(sets);
32 
33        
34 
35         ConfigurableApplicationContext applicationContext = application.run(args);
36         applicationContext.getBean(Runnable.class).run();
37         System.out.println(applicationContext.getBean(User.class));
38     }
39 
40 
41 }

View Code

建立ApplicationDemo

 1 package com.srpingboot.nostatic;
 2 
 3 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 4 import org.springframework.context.annotation.Bean;
 5 import org.springframework.context.annotation.ComponentScan;
 6 
 7 /**
 8  * Created by
 9  *
10  * @author: liuya
11  * @Date: 2018/5/20 2:23
12  * @Description: quick_start
13  */
14 @ComponentScan
15 @EnableAutoConfiguration
16 public class ApplicationDemo {
17 
18     @Bean
19     public Runnable createRunnable() {
20 
21         return () -> {
22             System.out.println("Spring Boot is Run");
23         };
24 
25     }
26 }

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方法三：构造函数指定方式

 1 package com.springboot;
 2 
 3 import com.srpingboot.nostatic.ApplicationDemo;
 4 import org.springframework.boot.SpringApplication;
 5 import org.springframework.context.ConfigurableApplicationContext;
 6 
 7 import java.util.HashSet;
 8 import java.util.Set;
 9 
10 /**
11  * Created by
12  *
13  * @author: liuya
14  * @Date: 2018/5/20 2:18
15  * @Description: quick_start
16  * <p>
17  * 指定多个源,调用非springApplication方法
18  */
19 
20 
21 public class ManyApplication {
22 
23     public static void main(String[] args) {
24 
25         //构造函数指定方式
26         SpringApplication application = new SpringApplication(ApplicationDemo.class,User.class);
27 
28 
29 
30         ConfigurableApplicationContext applicationContext = application.run(args);
31         applicationContext.getBean(Runnable.class).run();
32         System.out.println(applicationContext.getBean(User.class));
33     }
34 
35 
36 }

View Code

源码地址：

https://github.com/liushaoye/quick_start

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