java：【@Import】和【ImportSelector】的简单示例

本文主要是介绍java：【@Import】和【ImportSelector】的简单示例，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

# 代码结构

在这里插入图片描述

# 项目【myBeanBranch】

【pom.xml】

<dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.2.15.RELEASE</version>
</dependency>
<dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>5.2.15.RELEASE</version>
</dependency>
<dependency><groupId>ch.qos.logback</groupId><artifactId>logback-classic</artifactId><version>1.2.11</version>
</dependency>
<dependency><groupId>jakarta.annotation</groupId><artifactId>jakarta.annotation-api</artifactId><version>1.3.5</version>
</dependency>

【BranchBean.java】

package com.chz.myBeanBranch.bean;@Slf4j
@Getter
@Setter
// 被【ImportSelector】指过来的类不需要添加【@Component】
public class BranchBean {private String name;@PostConstructpublic void init(){name = "BranchBeanName put in from @PostConstruct";}
}

【BranchController.java】

package com.chz.myBeanBranch.controller;// 被【ImportSelector】指过来的类不需要添加【@RestController】，但要加【@ResponseBody】
@Slf4j
@ResponseBody
@RequestMapping("/branch")
public class BranchController {@Autowiredprivate BranchBean branchBean;@GetMapping("/test1")public String test1() {return "test1: " + branchBean.getName();}
}

【BranchImportBean.java】

package com.chz.myBeanBranch.importSelector;// 被【@Bean】指过来的类不需要添加【@Component】
@Getter
@Setter
public class BranchImportBean 
{private Integer id = 1;private String name = "BranchImportBeanName";
}

【BranchImportConfiguration.java】

package com.chz.myBeanBranch.importSelector;// 被【ImportSelector】指过来的类不需要添加【@Configuration】
public class BranchImportConfiguration 
{@Beanpublic BranchImportBean branchImportBean() {BranchImportBean branchBean = new BranchImportBean();branchBean.setId(19);branchBean.setName("I am branchImportBean!!!");return branchBean;}
}

【BranchImportSelector.java】

package com.chz.myBeanBranch.importSelector;public class BranchImportSelector implements ImportSelector
{@Overridepublic String[] selectImports(AnnotationMetadata annotationMetadata){// 这里想让哪个类变成bean就在返回值里面返回，所以ImportSelector可以用来做为动态添加bean的一个方法，// 比如扫描某一个自定义注解，然后返回类名，变成beanreturn new String[]{BranchImportConfiguration.class.getName(),BranchController.class.getName(),BranchBean.class.getName()};}
}

【EnableBranchImportSelector.java】

package com.chz.myBeanBranch.importSelector;@Retention(RetentionPolicy.RUNTIME)
@Documented
@Target(ElementType.TYPE)
@Import(BranchImportSelector.class)   // 这里使用了@ImportSelector
public @interface EnableBranchImportSelector {
}

# 项目【myBeanMain】

【pom.xm】

<dependency><groupId>com.chz</groupId><artifactId>myBeanBranch</artifactId><version>${project.version}</version>
</dependency>
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId><version>2.3.12.RELEASE</version>
</dependency>
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId><version>2.3.12.RELEASE</version>
</dependency>
<dependency><groupId>ch.qos.logback</groupId><artifactId>logback-classic</artifactId><version>1.2.11</version>
</dependency>

【application.properties】

server.port=8080
spring.application.name=myBeanMainmanagement.server.port=7001
management.endpoints.web.exposure.include=*

【MainBean.java】

package com.chz.myBeanMain.bean;@Getter
@Setter
@Component
public class MainBean
{@Autowiredprivate NotAnnotatedBean notAnnotatedBean;@Autowiredprivate BranchBean branchBean;@Autowiredprivate BranchImportBean branchImportBean;
}

【NotAnnotatedBean.java】

package com.chz.myBeanMain.bean;// 被【@Import】指过来的bean不需要添加【@Component】
@Getter
@Setter
public class NotAnnotatedBean 
{private String name = "I am " + this.getClass().getSimpleName();
}

【MainController.java】

package com.chz.myBeanMain.controller;@Slf4j
@RestController
@RequestMapping("/main")
public class MainController 
{@Autowiredprivate MainBean mainBean;@GetMapping("/notAnnotatedBean")public String notAnnotatedBean() {return "notAnnotatedBean: " + mainBean.getNotAnnotatedBean().getName();}@GetMapping("/branchBean")public String branchBean() {return "branchBean: " + mainBean.getBranchBean().getName();}@GetMapping("/branchImportBean")public String branchImportBean() {return "branchImportBean: " + mainBean.getBranchImportBean().getName();}
}

【MyBeanMainTest.java】

package com.chz.myBeanMain;@Import(NotAnnotatedBean.class)         // 这里使用了@Import
@EnableBranchImportSelector             // 这里使用了@ImportSelector
@SpringBootApplication
public class MyBeanMainTest 
{public static void main(String[] args) {SpringApplication.run(MyBeanMainTest.class, args);}
}

# 测试

启动【MyBeanMainTest】，然后：

访问【http://localhost:8080/branch/test1】
在这里插入图片描述
访问【http://localhost:8080/main/branchBean】

访问【http://localhost:8080/main/branchImportBean】

访问【http://localhost:8080/main/notAnnotatedBean】