Spring注記-@Conditionalを使用して条件に従ってbeanを登録

1.異なる条件に従って異なるbeanを生成する必要がある場合があり、@Conditional注釈を使用する必要があります.一般的な使い方の1つは、オペレーティングシステムのタイプに応じて、異なるbeanを登録することです.BeanConfig構成クラスに3つのbeanを追加します.

package io.mieux.config;

import io.mieux.bean.Person;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class BeanConfig {

    @Bean(value = "zhangsan")
    public Person getPerson() {
        return new Person("zhangsan", 28);
    }

    @Bean(value = "linux")
    public Person getLinux() {
        return new Person("linux", 50);
    }

    @Bean(value = "windows")
    public Person getWindows() {
        return new Person("windows", 30);
    }

    @Bean(value = "mac")
    public Person getMac() {
        return new Person("mac", 24);
    }
}

現在のコンテナのPersonクラスのインスタンスを表示します.

package io.mieux;

import io.mieux.bean.Person;
import io.mieux.config.BeanConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class App04 {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(BeanConfig.class);
        String[] beanNames = annotationConfigApplicationContext.getBeanNamesForType(Person.class);
        for (String beanName : beanNames) {
            System.out.println("beanName: " + beanName);
        }
    }
}

実行効果:

beanName: zhangsan
beanName: linux
beanName: windows
beanName: mac

2.@Conditional注記を使用して、オペレーティングシステムによって異なるbeanを登録します.まずConditionインタフェースを実装し,3つのConditionインタフェースの実装クラスLinuxConditon,MacConditon,WindowsConditonを作成し,実行環境のオペレーティングシステムタイプを取得して判断する必要がある.
LinuxConditon:

package io.mieux.condition;

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

//       linux   
public class LinuxConditon implements Condition {

    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        Environment environment = context.getEnvironment();

        String operatingSystem = environment.getProperty("os.name");
        if ("linux".equals(operatingSystem)) {
            System.out.println("Operating System: " + environment.getProperty("os.name"));
            return true;
        }
        return false;
    }
}

WindowsConditon:

package io.mieux.condition;

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

//       windows   
public class WindowsConditon implements Condition {

    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        Environment environment = context.getEnvironment();

        String operatingSystem = environment.getProperty("os.name");
        if (operatingSystem.contains("Windows")) {
            System.out.println("Operating System: " + environment.getProperty("os.name"));
            return true;
        }
        return false;
    }
}

MacConditon:

package io.mieux.condition;

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

//       mac os   
public class MacConditon implements Condition {

    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        Environment environment = context.getEnvironment();

        String operatingSystem = environment.getProperty("os.name");
        if ("Mac OS X".equals(operatingSystem)) {
            System.out.println("Operating System: " + environment.getProperty("os.name"));
            return true;
        }
        return false;
    }
}

BeanConfig構成クラスに@Conditional注記を付けます.

package io.mieux.config;

import io.mieux.bean.Person;
import io.mieux.condition.LinuxConditon;
import io.mieux.condition.MacConditon;
import io.mieux.condition.WindowsConditon;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;

@Configuration
public class BeanConfig {

    @Bean(value = "zhangsan")
    public Person getPerson() {
        return new Person("zhangsan", 28);
    }

    @Bean(value = "linux")
    @Conditional(value = {LinuxConditon.class})
    public Person getLinux() {
        return new Person("linux", 50);
    }

    @Bean(value = "windows")
    @Conditional(value = {WindowsConditon.class})
    public Person getWindows() {
        return new Person("windows", 30);
    }

    @Bean(value = "mac")
    @Conditional(value = {MacConditon.class})
    public Person getMac() {
        return new Person("mac", 24);
    }
}

実行効果:

Operating System: Mac OS X
beanName: zhangsan
beanName: mac