java spring boot 自动配置 条件注入

1.概要

满足条件的话，就会注入bean.

2 代码

2.1 要注入的可选bean

package com.example.demo;

public class User {
}

2.2 配置文件 

package com.example.demo;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;

@Configuration
public class UserCinfig {
    @Bean
    //@Conditional({CondiationClass.class})
    @CondationOnClass("redis.clients.jedis.Jedis")
    public User user(){
        return new User();
    }
}

2.3 条件配置类 

package com.example.demo;

import org.springframework.context.annotation.Conditional;

import java.lang.annotation.*;

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Conditional({CondiationClass.class})
public @interface CondationOnClass {
    String[] value();
}

 2.4 条件判断接口

package com.example.demo;

import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;

import java.util.Map;

public class CondiationClass implements Condition {
    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {

        final Map<String, Object> annotationAttributes = metadata.getAnnotationAttributes(CondationOnClass.class.getName());
        //System.out.println(annotationAttributes);
        assert annotationAttributes != null;
        String[] valuse = (String[]) annotationAttributes.get("value");
        boolean ret = true;
        try {
            for (String str:valuse){
                //Class<?> c = Class.forName("redis.clients.jedis.Jedis");
                Class<?> c = Class.forName(str);
            }
            //redis.clients.jedis.Jedis

        }catch (Exception e){
            ret = false;
        }
        return ret;
    }
}

2.5 执行的主函数 

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import com.example.demo.MyUser;
import com.example.demo.UserConfig;
import org.springframework.context.annotation.Import;

import java.util.Map;

@SpringBootApplication
//@Import(MyUser.class)
//@Import(UserConfig.class)
//@Import(MyImportSelecter.class)
//@Import(MyImportBeanDefinitionRegistrar.class)
public class Demo2Application {

    public static void main(String[] args) {

        ConfigurableApplicationContext configurableApplicationContext = SpringApplication.run(Demo2Application.class, args);
        User user = (User) configurableApplicationContext.getBean("user");
        System.out.println(user);
        //MyUser myUser = (MyUser) configurableApplicationContext.getBean("myUser2");
        //System.out.println(myUser);

        //Map<String,MyUser> map = configurableApplicationContext.getBeansOfType(MyUser.class);
        //System.out.println(map);
    }

}

3 运行结果

C:\Users\ThinkPad\.jdks\openjdk-21.0.2\bin\java.exe -XX:TieredStopAtLevel=1 -Dspring.output.ansi.enabled=always -Dcom.sun.management.jmxremote -Dspring.jmx.enabled=true -Dspring.liveBeansView.mbeanDomain -Dspring.application.admin.enabled=true "-Dmanagement.endpoints.jmx.exposure.include=*" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA 2023.3.2\lib\idea_rt.jar=54031:D:\Program Files\JetBrains\IntelliJ IDEA 2023.3.2\bin" -Dfile.encoding=UTF-8 -Dsun.stdout.encoding=UTF-8 -Dsun.stderr.encoding=UTF-8 -classpath C:\Users\ThinkPad\IdeaProjects\untitled7\demo2\target\classes;C:\Users\ThinkPad\.m2\repository\org\springframework\boot\spring-boot-starter-data-redis\3.2.2\spring-boot-starter-data-redis-3.2.2.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\boot\spring-boot-starter\3.2.2\spring-boot-starter-3.2.2.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\boot\spring-boot\3.2.2\spring-boot-3.2.2.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-context\6.1.3\spring-context-6.1.3.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-expression\6.1.3\spring-expression-6.1.3.jar;C:\Users\ThinkPad\.m2\repository\io\micrometer\micrometer-observation\1.12.2\micrometer-observation-1.12.2.jar;C:\Users\ThinkPad\.m2\repository\io\micrometer\micrometer-commons\1.12.2\micrometer-commons-1.12.2.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\boot\spring-boot-autoconfigure\3.2.2\spring-boot-autoconfigure-3.2.2.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\boot\spring-boot-starter-logging\3.2.2\spring-boot-starter-logging-3.2.2.jar;C:\Users\ThinkPad\.m2\repository\ch\qos\logback\logback-classic\1.4.14\logback-classic-1.4.14.jar;C:\Users\ThinkPad\.m2\repository\ch\qos\logback\logback-core\1.4.14\logback-core-1.4.14.jar;C:\Users\ThinkPad\.m2\repository\org\apache\logging\log4j\log4j-to-slf4j\2.21.1\log4j-to-slf4j-2.21.1.jar;C:\Users\ThinkPad\.m2\repository\org\apache\logging\log4j\log4j-api\2.21.1\log4j-api-2.21.1.jar;C:\Users\ThinkPad\.m2\repository\org\slf4j\jul-to-slf4j\2.0.11\jul-to-slf4j-2.0.11.jar;C:\Users\ThinkPad\.m2\repository\jakarta\annotation\jakarta.annotation-api\2.1.1\jakarta.annotation-api-2.1.1.jar;C:\Users\ThinkPad\.m2\repository\org\yaml\snakeyaml\2.2\snakeyaml-2.2.jar;C:\Users\ThinkPad\.m2\repository\io\lettuce\lettuce-core\6.3.1.RELEASE\lettuce-core-6.3.1.RELEASE.jar;C:\Users\ThinkPad\.m2\repository\io\netty\netty-common\4.1.105.Final\netty-common-4.1.105.Final.jar;C:\Users\ThinkPad\.m2\repository\io\netty\netty-handler\4.1.105.Final\netty-handler-4.1.105.Final.jar;C:\Users\ThinkPad\.m2\repository\io\netty\netty-resolver\4.1.105.Final\netty-resolver-4.1.105.Final.jar;C:\Users\ThinkPad\.m2\repository\io\netty\netty-buffer\4.1.105.Final\netty-buffer-4.1.105.Final.jar;C:\Users\ThinkPad\.m2\repository\io\netty\netty-transport-native-unix-common\4.1.105.Final\netty-transport-native-unix-common-4.1.105.Final.jar;C:\Users\ThinkPad\.m2\repository\io\netty\netty-codec\4.1.105.Final\netty-codec-4.1.105.Final.jar;C:\Users\ThinkPad\.m2\repository\io\netty\netty-transport\4.1.105.Final\netty-transport-4.1.105.Final.jar;C:\Users\ThinkPad\.m2\repository\io\projectreactor\reactor-core\3.6.2\reactor-core-3.6.2.jar;C:\Users\ThinkPad\.m2\repository\org\reactivestreams\reactive-streams\1.0.4\reactive-streams-1.0.4.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\data\spring-data-redis\3.2.2\spring-data-redis-3.2.2.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\data\spring-data-keyvalue\3.2.2\spring-data-keyvalue-3.2.2.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\data\spring-data-commons\3.2.2\spring-data-commons-3.2.2.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-tx\6.1.3\spring-tx-6.1.3.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-beans\6.1.3\spring-beans-6.1.3.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-oxm\6.1.3\spring-oxm-6.1.3.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-aop\6.1.3\spring-aop-6.1.3.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-context-support\6.1.3\spring-context-support-6.1.3.jar;C:\Users\ThinkPad\.m2\repository\redis\clients\jedis\5.2.0-alpha2\jedis-5.2.0-alpha2.jar;C:\Users\ThinkPad\.m2\repository\org\slf4j\slf4j-api\2.0.11\slf4j-api-2.0.11.jar;C:\Users\ThinkPad\.m2\repository\org\apache\commons\commons-pool2\2.12.0\commons-pool2-2.12.0.jar;C:\Users\ThinkPad\.m2\repository\org\json\json\20231013\json-20231013.jar;C:\Users\ThinkPad\.m2\repository\com\google\code\gson\gson\2.10.1\gson-2.10.1.jar;C:\Users\ThinkPad\IdeaProjects\untitled7\demo1\target\classes;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-core\6.1.3\spring-core-6.1.3.jar;C:\Users\ThinkPad\.m2\repository\org\springframework\spring-jcl\6.1.3\spring-jcl-6.1.3.jar com.example.demo.Demo2Application

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.2.2)

2024-01-30T22:01:26.023+08:00  INFO 12236 --- [           main] com.example.demo.Demo2Application        : Starting Demo2Application using Java 21.0.2 with PID 12236 (C:\Users\ThinkPad\IdeaProjects\untitled7\demo2\target\classes started by ThinkPad in C:\Users\ThinkPad\IdeaProjects\untitled7)
2024-01-30T22:01:26.027+08:00  INFO 12236 --- [           main] com.example.demo.Demo2Application        : No active profile set, falling back to 1 default profile: "default"
2024-01-30T22:01:26.531+08:00  INFO 12236 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Multiple Spring Data modules found, entering strict repository configuration mode
2024-01-30T22:01:26.536+08:00  INFO 12236 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data Redis repositories in DEFAULT mode.
2024-01-30T22:01:26.570+08:00  INFO 12236 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 13 ms. Found 0 Redis repository interfaces.
2024-01-30T22:01:27.424+08:00  INFO 12236 --- [           main] com.example.demo.Demo2Application        : Started Demo2Application in 1.903 seconds (process running for 2.882)
com.example.demo.User@1756f7cc

Process finished with exit code 0