package cs.yangtze.springboot_condition;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
@SpringBootApplication
public class SpringbootConditionApplication {
    public static void main(String[] args) {
        //啟動(dòng)springboot的應(yīng)用，返回spring的IOC容器
        ConfigurableApplicationContext context = SpringApplication.run(SpringbootConditionApplication.class, args);
        //獲取bean，redisTemplate
        Object redisTemplate = context.getBean("redisTemplate");
        System.out.println(redisTemplate);
    }
}

<dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

package cs.yangtze.springboot_condition.condition;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
public class ClassCondition implements Condition {
    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        //需求：導(dǎo)入jedis坐標(biāo)后創(chuàng)建Bean
        boolean flag = true;
        try {
            Class<?> aClass = Class.forName("redis.clients.jedis.Jedis");
        } catch (ClassNotFoundException e) {
            flag = false;
        }
        return flag;
    }
}

package cs.yangtze.springboot_condition.config;
import cs.yangtze.springboot_condition.condition.ClassCondition;
import cs.yangtze.springboot_condition.entity.User;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
@Configuration
public class UserConfig {
    @Bean//用于在容器中闖進(jìn)Bean對(duì)象
    @Conditional(ClassCondition.class)  //參數(shù)是一個(gè)或多個(gè)condition的實(shí)現(xiàn)類
    public User user(){
        return new User();
    }
}

package cs.yangtze.springboot_condition;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
@SpringBootApplication
public class SpringbootConditionApplication {
    public static void main(String[] args) {
        //啟動(dòng)springboot的應(yīng)用，返回spring的IOC容器
        ConfigurableApplicationContext context = SpringApplication.run(SpringbootConditionApplication.class, args);
        //獲取bean，redisTemplate
        Object redisTemplate = context.getBean("redisTemplate");
        System.out.println(redisTemplate);
 		//此處getBean方法中的參數(shù)是UserConfig類中的方法名稱，當(dāng)然也可以在@Bean注解后加入名稱，如@Bean("aaa"),那么此處的user就應(yīng)換成aaa
        Object user = context.getBean("user");
        System.out.println(user);
    }
}

  <dependency>
        <groupId>redis.clients</groupId>
        <artifactId>jedis</artifactId>
  </dependency>