BeanFactory

介绍

👋 Hi, I’m @DSXRIIIII
👀 该项目旨在帮助初学者对Bean注入方式的思考和理解👑
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在项目构建中当我们使用模板方法模式时我们需要创建一个规范化接口定义方法的行为准则
此时我们使用注解@Service或者@Component注解时可能会出现一些问题

设计代码

//定义接口
/**
 * @ProjectName: `Bean`Map
 * @Description: 定义行为规范
 * @Author: DSXRIIIII
 * @CreateDate: 2024/7/19 17:09
 * @Email: lihh53453@hundsun.com
 */
public interface IService {
    public void doLogin();
    public void doChange();
}

//定义实现类
@Service
public class UserService implements IService {
    @Override
    public void doLogin() {
        System.out.println("调用用户doLogin方法( •̀ ω •́ )✧");
    }

    @Override
    public void doChange() {
        System.out.println("调用用户doChange方法ヾ(≧ ▽ ≦)ゝ");
    }
}

@Service
public class CustomerService implements IService {
    @Override
    public void doLogin() {
        System.out.println("调用消费者doLogin方法( •̀ ω •́ )✧");
    }

    @Override
    public void doChange() {
        System.out.println("调用消费者doChange方法ヾ(≧ ▽ ≦)ゝ");
    }
}

//`Bean`注入自动调用
@Component
public class ServiceInvoke {
    @Resource
    private IService service;

    @`Bean`
    public void invoke_service(){
        service.doChange();
        service.doLogin();
    }
}

此时会报错：
:::danger
org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘serviceInvoke’: Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type ‘cn.dsxriiiii.middleware.protocol.IService’ available: expected single matching bean but found 2: customerService,userService
:::
说明此时IOC找到了两个Bean 但是不知道使用的是哪一个

方案一

使用**@Primary**注解：可以将其中一个bean标记为@Primary，这样当存在多个候选bean时，Spring将优先选择被标记为@Primary的bean进行自动装配。

//添加注解
@Primary
@Service
public class UserService implements IService {
    @Override
    public void doLogin() {
        System.out.println("调用UserService用户doLogin方法( •̀ ω •́ )✧");
    }

    @Override
    public void doChange() {
        System.out.println("调用UserService用户doChange方法ヾ(≧ ▽ ≦)ゝ");
    }
}

//此时启动项目时 
打印日志如下
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::               (v2.7.12)

2024-07-19 17:27:49.344  INFO 26980 --- [           main] cn.dsxriiiii.middleware.Application      : Starting Application using Java 1.8.0_401 on DESKTOP-50PSSHU with PID 26980 (D:\JAVAProject\HaHa\`Bean`Map\target\classes started by hspcadmin in D:\JAVAProject\HaHa\`Bean`Map)
2024-07-19 17:27:49.347  INFO 26980 --- [           main] cn.dsxriiiii.middleware.Application      : No active profile set, falling back to 1 default profile: "default"
2024-07-19 17:27:49.873  INFO 26980 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2024-07-19 17:27:49.878  INFO 26980 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2024-07-19 17:27:49.878  INFO 26980 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.75]
2024-07-19 17:27:50.034  INFO 26980 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2024-07-19 17:27:50.034  INFO 26980 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 649 ms
调用UserService用户doChange方法ヾ(≧ ▽ ≦)ゝ
调用UserService用户doLogin方法( •̀ ω •́ )✧
2024-07-19 17:27:50.306  INFO 26980 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2024-07-19 17:27:50.314  INFO 26980 --- [           main] cn.dsxriiiii.middleware.Application      : Started Application in 1.23 seconds (JVM running for 2.085)

方案二

使用**@Qualifier**注解：如果不想或不能使用@Primary，可以在自动装配的地方使用@Qualifier注解来指定需要注入的具体bean的名称。

//注入的时候添加注解
@Resource
@Qualifier("customerService")
private IService service;

//输出日志
  .   ____          _            __ _ _
  /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
  ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
  =========|_|==============|___/=/_/_/_/
  :: Spring Boot ::               (v2.7.12)

  2024-07-19 17:42:02.941  INFO 25308 --- [           main] cn.dsxriiiii.middleware.Application      : Starting Application using Java 1.8.0_401 on DESKTOP-50PSSHU with PID 25308 (D:\JAVAProject\HaHa\`Bean`Map\target\classes started by hspcadmin in D:\JAVAProject\HaHa\`Bean`Map)
  2024-07-19 17:42:02.946  INFO 25308 --- [           main] cn.dsxriiiii.middleware.Application      : No active profile set, falling back to 1 default profile: "default"
  2024-07-19 17:42:03.769  INFO 25308 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
  2024-07-19 17:42:03.775  INFO 25308 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
  2024-07-19 17:42:03.776  INFO 25308 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.75]
  2024-07-19 17:42:03.939  INFO 25308 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
  2024-07-19 17:42:03.939  INFO 25308 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 912 ms
  调用CustomerService消费者doChange方法ヾ(≧ ▽ ≦)ゝ
  调用CustomerService消费者doLogin方法( •̀ ω •́ )✧
  2024-07-19 17:42:04.319  INFO 25308 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
  2024-07-19 17:42:04.329  INFO 25308 --- [           main] cn.dsxriiiii.middleware.Application      : Started Application in 1.768 seconds (JVM running for 2.738)

方案三

使用构造方法注入：当存在多个相同类型的Bean需要注入时，可以使用构造方法注入，并将这些Bean作为参数传递。Spring框架会自动识别并注入所有匹配的Bean，你可以通过在构造方法参数上使用@Qualifier注解来区分它们。此外，Spring允许将所有匹配的Bean自动装配到一个Map集合中，其中Map的键是Bean的名称，值是Bean实例本身

//创建Factory工厂类
//定义调用方法
public interface IServiceFactory {
    void process();
}

//在实现类上 我们需要定义一个Map Spring框架可以自动注入
@Service
public class ServiceFactory implements IServiceFactory {

    private final Map<String, IService> ServiceGroup;

    public ServiceFactory(Map<String, IService> ServiceNodeGroup) {
        this.ServiceGroup = ServiceNodeGroup;
    }

    @Override
    public void process() {
        ServiceGroup.get("userService").doLogin();
        ServiceGroup.get("customerService").doLogin();
    }
}

日志如下
.   ____          _            __ _ _
/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/  ___)| |_)| | | | | || (_| |  ) ) ) )
'  |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot ::               (v2.7.12)

2024-07-19 18:08:06.972  INFO 20964 --- [           main] cn.dsxriiiii.middleware.Application      : Starting Application using Java 1.8.0_401 on DESKTOP-50PSSHU with PID 20964 (D:\JAVAProject\HaHa\`Bean`Map\target\classes started by hspcadmin in D:\JAVAProject\HaHa\`Bean`Map)
2024-07-19 18:08:06.976  INFO 20964 --- [           main] cn.dsxriiiii.middleware.Application      : No active profile set, falling back to 1 default profile: "default"
2024-07-19 18:08:07.731  INFO 20964 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2024-07-19 18:08:07.738  INFO 20964 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2024-07-19 18:08:07.738  INFO 20964 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.75]
2024-07-19 18:08:07.879  INFO 20964 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2024-07-19 18:08:07.879  INFO 20964 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 846 ms
调用UserService用户doLogin方法( •̀ ω •́ )✧
调用CustomerService消费者doLogin方法( •̀ ω •́ )✧
2024-07-19 18:08:08.173  INFO 20964 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2024-07-19 18:08:08.182  INFO 20964 --- [           main] cn.dsxriiiii.middleware.Application      : Started Application in 1.61 seconds (JVM running for 2.81)

BeanFactory

介绍

设计代码

方案一

方案二

方案三

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