如何使用SpringBootCondition更自由地定义条件化配置

import com.example.conditional.MyConditional;

import org.springframework.context.annotation.Conditional;

import java.lang.annotation.*;

@Target ({ElementType.TYPE,ElementType.METHOD})

@Retention (RetentionPolicy.RUNTIME)

@Documented

@Conditional (MyConditional. class )

public @interface MyConditionalIAnnotation {

   String key();

   String value();

}

import com.example.conditional.interfaceI.MyConditionalIAnnotation;

import org.springframework.boot.autoconfigure.condition.ConditionOutcome;

import org.springframework.boot.autoconfigure.condition.SpringBootCondition;

import org.springframework.context.annotation.ConditionContext;

import org.springframework.context.annotation.Conditional;

import org.springframework.core.type.AnnotatedTypeMetadata;

import java.util.Map;

public class MyConditional extends SpringBootCondition {

   @Override

   public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {

     Map<String, Object> annotationAttributes = metadata.getAnnotationAttributes(MyConditionalIAnnotation. class .getName());

     Object key = annotationAttributes.get( "key" ); //

     Object value = annotationAttributes.get( "value" );

     if (key == null || value == null ){

       return new ConditionOutcome( false , "error" );

     }

     //获取environment中的值

     String key1 = context.getEnvironment().getProperty(key.toString());

     if (value.equals(key1)) {

       //如果environment中的值与指定的value一致，则返回true

       return new ConditionOutcome( true , "ok" );

     }

     return new ConditionOutcome( false , "error" );

   }

}

import com.example.conditional.interfaceI.MyConditionalIAnnotation;

import com.example.conditional.service.MyConditionalService;

import org.apache.log4j.Logger;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;

import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;

import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.ComponentScan;

import org.springframework.context.annotation.Configuration;

@Configuration

public class MyConditionalConfig {

   public static Logger logger=Logger.getLogger(MyConditionalService. class );

   /**

    * 判断MyConditional 是否符合条件，是则运行MyConditionalService

    * @return

    */

   @MyConditionalIAnnotation (key = "com.example.conditional" , value = "lbl" )

   @ConditionalOnClass (MyConditionalService. class )

   @Bean

   public MyConditionalService initMyConditionService() {

     logger.info( "MyConditionalService已加载。" );

     return new MyConditionalService();

   }

}

spring.application.name=gateway

server.port=8084

#conditional 动态配置，判断该值是否等于lbl，是则创建MyConditionalService实例

com.example.conditional=lbl

#支持自定义aop

spring.aop.auto= true

@ConditionalOnProperty (prefix = "pkslow" , name = "service" , havingValue = "larry" )

@ConditionalOnBean （仅仅在当前上下文中存在某个对象时，才会实例化一个Bean）

@ConditionalOnClass （某个 class 位于类路径上，才会实例化一个Bean）

@ConditionalOnExpression （当表达式为 true 的时候，才会实例化一个Bean）

@ConditionalOnMissingBean （仅仅在当前上下文中不存在某个对象时，才会实例化一个Bean）

@ConditionalOnMissingClass （某个 class 类路径上不存在的时候，才会实例化一个Bean）

@ConditionalOnNotWebApplication （不是web应用）

public class PkslowCondition extends SpringBootCondition {

  @Override

  public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {

   BindResult<List<String>> maxBindResult = Binder.get(context.getEnvironment()).bind( "pkslow.condition.max" , Bindable.listOf(String. class ));

   BindResult<List<String>> minBindResult = Binder.get(context.getEnvironment()).bind( "pkslow.condition.min" , Bindable.listOf(String. class ));

   if ( (maxBindResult.isBound() && !maxBindResult.get().isEmpty()) && (minBindResult.isBound() && !minBindResult.get().isEmpty()) ) {

    List<String> maxs = maxBindResult.get();

    List<String> mins = minBindResult.get();

    int max = Integer.parseInt(maxs.get( 0 ));

    int min = Integer.parseInt(mins.get( 0 ));

    if (max < 1000 && min > 0 ) {

     return ConditionOutcome.match();

    }

   }

   return ConditionOutcome.noMatch( "pkslow.condition.max/pkslow.condition.min not matches" );

  }

}

@Conditional (PkslowCondition. class )

@Configuration

public class PkslowConfig {

   @PostConstruct

   public void postConstruct() {

     System.out.println( "PkslowConfig called" );

   }

}