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文章目录
SpringFramework

Spring 条件装配

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2021-01-17 / 0 评论 / 1 点赞 / 1790 阅读 / 0 字

主要功能当条件符合时进行装配 不符合则不进行装配

@Conditional 基于编程的条件装配

  • 例如要实现 当系统用户名为 65722 时进行装配 则代码如下

  • 注解类

package com.example.demo.condition;

import org.springframework.context.annotation.Conditional;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Spring条件装配
 * 当注解所标注的键值对与系统中的匹配时 才会进行装配
 *
 * @author mengshuo
 * @since 2021-01-17 10:01:37
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Conditional(OnSystemCondition.class)
public @interface SystemTypeConditional {

    /**
     * 系统参数键
     *
     * @return res
     */
    String key();

    /**
     * 系统参数值
     *
     * @return res
     */
    String value();
}
  • Condition 实现类 主要用与判断是否符合装配条件
package com.example.demo.condition;

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

import java.util.Map;

/**
 * 注入条件判断类
 *
 * @author mengshuo
 * @since 2021-01-17 10:05:41
 */
public class OnSystemCondition implements Condition {

    /**
     * 验证是否注解中属性是否与系统属性一致
     *
     * @param context  应用上下文
     * @param metadata 注解信息
     * @return 验证结果
     */
    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {

        Map<String, Object> attributes = metadata.getAnnotationAttributes(SystemTypeConditional.class.getName());
        if (attributes == null) return false;
        String key = String.valueOf(attributes.get("key"));
        String value = String.valueOf(attributes.get("value"));
        if (key.isEmpty() || value.isEmpty()) return false;
        //验证注解中的属性是否符合系统中的属性
        return System.getProperty(key).equals(value);
    }
}
  • 需要进行条件装配 的服务
package com.example.demo.condition;

import org.springframework.stereotype.Service;

/**
 * 系统服务bean
 *
 * @author mengshuo
 * @since 2021-01-17 11:09:17
 */
@SystemTypeConditional(key = "user.name", value = "65722")
@Service
public class SystemService {
    public void print() {
        System.out.println("---- 系统服务已经装配 ----");
    }
}
  • 启动类 这里因为没有使用@SpringBootApplication 注解所以需要手动去指定包扫描路径
package com.example.demo.condition;

import org.springframework.boot.WebApplicationType;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.ComponentScan;

/**
 * 主类
 *
 * @author mengshuo
 * @since 2021-01-17 11:05:37
 */
@ComponentScan(basePackages = "com.example.demo.condition")
public class ConditionRun {

    public static void main(String[] args) {
        ConfigurableApplicationContext run = new SpringApplicationBuilder(ConditionRun.class)
                .web(WebApplicationType.NONE)
                .run(args);
        SystemService service = run.getBean(SystemService.class);
        service.print();
        run.close();
    }
}
  • 运行结果
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.3.4.RELEASE)

2021-01-17 11:48:20.823  INFO 13472 --- [           main] com.example.demo.condition.ConditionRun  : Starting ConditionRun on DESKTOP-4M5DVU4 with PID 13472 (E:\WorkSpace\demo\target\classes started by 65722 in E:\WorkSpace\demo)
2021-01-17 11:48:20.838  INFO 13472 --- [           main] com.example.demo.condition.ConditionRun  : No active profile set, falling back to default profiles: default
2021-01-17 11:48:21.057  INFO 13472 --- [           main] com.example.demo.condition.ConditionRun  : Started ConditionRun in 0.743 seconds (JVM running for 1.379)
---- 系统服务已经装配 ----
与目标 VM 断开连接, 地址为: ''127.0.0.1:57658'，传输: '套接字''

进程已结束,退出代码0
  • 将SystemService 中@SystemTypeConditional(key = "user.name", value = "65722") 改为 @SystemTypeConditional(key = "user.name", value = "123456") 则获取不到该类型Bean 说明未被装配
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.3.4.RELEASE)

2021-01-17 11:48:47.705  INFO 3932 --- [           main] com.example.demo.condition.ConditionRun  : Starting ConditionRun on DESKTOP-4M5DVU4 with PID 3932 (E:\WorkSpace\demo\target\classes started by 65722 in E:\WorkSpace\demo)
2021-01-17 11:48:47.721  INFO 3932 --- [           main] com.example.demo.condition.ConditionRun  : No active profile set, falling back to default profiles: default
2021-01-17 11:48:47.924  INFO 3932 --- [           main] com.example.demo.condition.ConditionRun  : Started ConditionRun in 0.686 seconds (JVM running for 1.372)
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.example.demo.condition.SystemService' available
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:351)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:342)
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1127)
	at com.example.demo.condition.ConditionRun.main(ConditionRun.java:21)
与目标 VM 断开连接, 地址为: ''127.0.0.1:57667'，传输: '套接字''

进程已结束,退出代码1

@Profile 基于配置的条件装配

  • 例如要实现 profiles 中有 root 字段则对 SystemService 进行装配

  • SystemService 代码

package com.example.demo.condition;

import org.springframework.context.annotation.Profile;
import org.springframework.stereotype.Service;

/**
 * 系统服务bean
 *
 * @author mengshuo
 * @since 2021-01-17 11:09:17
 */
@Profile("root")
@Service
public class SystemService {
    public void print() {
        System.out.println("---- 系统服务已经装配 ----");
    }
}
  • 启动类
package com.example.demo.condition;

import org.springframework.boot.WebApplicationType;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.ComponentScan;

/**
 * 主类
 *
 * @author mengshuo
 * @since 2021-01-17 11:05:37
 */
@ComponentScan(basePackages = "com.example.demo.condition")
public class ConditionRun {

    public static void main(String[] args) {
        ConfigurableApplicationContext run = new SpringApplicationBuilder(ConditionRun.class)
                .profiles("root")
                .web(WebApplicationType.NONE)
                .run(args);
        SystemService service = run.getBean(SystemService.class);
        service.print();
        run.close();
    }
}
  • 运行结果
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.3.4.RELEASE)

2021-01-17 11:45:34.508  INFO 9744 --- [           main] com.example.demo.condition.ConditionRun  : Starting ConditionRun on DESKTOP-4M5DVU4 with PID 9744 (E:\WorkSpace\demo\target\classes started by 65722 in E:\WorkSpace\demo)
2021-01-17 11:45:34.508  INFO 9744 --- [           main] com.example.demo.condition.ConditionRun  : The following profiles are active: root
2021-01-17 11:45:34.758  INFO 9744 --- [           main] com.example.demo.condition.ConditionRun  : Started ConditionRun in 0.72 seconds (JVM running for 1.386)
---- 系统服务已经装配 ----
与目标 VM 断开连接, 地址为: ''127.0.0.1:57639'，传输: '套接字''

进程已结束,退出代码0
  • 若将profiles 中 root 删除或者改为其他 则运行结果为
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.3.4.RELEASE)

2021-01-17 11:46:04.223  INFO 3084 --- [           main] com.example.demo.condition.ConditionRun  : Starting ConditionRun on DESKTOP-4M5DVU4 with PID 3084 (E:\WorkSpace\demo\target\classes started by 65722 in E:\WorkSpace\demo)
2021-01-17 11:46:04.226  INFO 3084 --- [           main] com.example.demo.condition.ConditionRun  : The following profiles are active: root1
2021-01-17 11:46:04.428  INFO 3084 --- [           main] com.example.demo.condition.ConditionRun  : Started ConditionRun in 0.675 seconds (JVM running for 1.314)
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.example.demo.condition.SystemService' available
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:351)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:342)
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1127)
	at com.example.demo.condition.ConditionRun.main(ConditionRun.java:22)
与目标 VM 断开连接, 地址为: ''127.0.0.1:57648'，传输: '套接字''

进程已结束,退出代码1
1
Spring手动装配
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