package com.example.config;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.stereotype.Component;
@Component
@ConditionalOnProperty(name = "custom.myComponent.enabled", havingValue = "true")
public class MyComponent {
    public MyComponent() {
        System.out.println("[MyComponent#MyComponent]");
    }
}

application.yml

custom:
myComponent:
enabled: true

運行結果：

[MyComponent#MyComponent]

若將application.yml的custom.myComponent.enabled去掉，或者設置為非true值，則不會輸出上邊的運行結果。

@Configuration+@Bean+條件注解

Bean

package com.example.config;
public class MyComponent {
    public MyComponent() {
        System.out.println("[MyComponent#MyComponent]");
    }
}

配置類

package com.example.config;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MyConfig {
    @Bean
    @ConditionalOnProperty(name = "custom.myComponent.enabled", havingValue = "true")
    public MyComponent getMyComponent() {
        return new MyComponent();
    }
}

application.yml

custom:
myComponent:
enabled: true

運行結果：

[MyComponent#MyComponent]

若將application.yml的custom.myComponent.enabled去掉，或者設置為非true值，則不會輸出上邊的運行結果。

@Configuration+條件注解+@Bean

Bean

package com.example.config;
public class MyComponent {
    public MyComponent() {
        System.out.println("[MyComponent#MyComponent]");
    }
}

配置類

package com.example.config;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
@ConditionalOnProperty(name = "custom.myComponent.enabled", havingValue = "true")
public class MyConfig {
    @Bean
    public MyComponent getMyComponent() {
        return new MyComponent();
    }
}

application.yml

custom:
myComponent:
enabled: true

運行結果：

[MyComponent#MyComponent]

若將application.yml的custom.myComponent.enabled去掉，或者設置為非true值，則不會輸出上邊的運行結果。

自定義Condition

自定義的condition的matches方法返回值為true時，才會創(chuàng)建bean。

條件類

//判斷當前系統(tǒng)是否是Mac

import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
public class MyCondition implements Condition {
    @Override
    public boolean matches(ConditionContext conditionContext, 
                           AnnotatedTypeMetadata annotatedTypeMetadata) {
        return conditionContext.getEnvironment().getProperty("os.name").contains("Mac");
    }
}

@Configuration
public class Config {
    @Conditional(MyCondition.class)
    @Bean
    public String condition() {
        System.err.println("This is mac");
        return "";
    }
}

到此這篇關于Spring示例講解條件注入方法的文章就介紹到這了,更多相關Spring條件注入內(nèi)容請搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關文章希望大家以后多多支持腳本之家！

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