Exercise 7

app/app/src/main/java/com/workshop/magic/app/WorkshopApplication.java

@@ -7,6 +7,7 @@ import org.springframework.boot.autoconfigure.SpringBootApplication;
 public class WorkshopApplication {
 
     public static void main(String[] args) {
+        System.setProperty("my.custom.condition", "true");
         SpringApplication.run(WorkshopApplication.class, args);
     }
 }

app/app/src/main/resources/application.properties

@@ -1,3 +1,3 @@
 debug=true
 workshop.greeting.text=Gude
-workshop.greeting.type=logger
+workshop.greeting.type=none

components/library-autoconfigure/src/main/java/com/workshop/magic/config/GreetingAutoConfiguration.java

@@ -1,6 +1,7 @@
 package com.workshop.magic.config;
 
 import com.workshop.magic.service.GreetingService;
+import com.workshop.magic.service.slf4j.BeepGreetingService;
 import com.workshop.magic.service.slf4j.LoggerGreetingService;
 import com.workshop.magic.service.stdout.StdOutGreetingService;
 
@@ -32,4 +33,11 @@ public class GreetingAutoConfiguration {
         return new LoggerGreetingService(properties.getText());
     }
 
+    @Bean
+    @ConditionalOnMissingBean
+    @MyCustomCondition
+    @ConditionalOnClass(BeepGreetingService.class)
+    GreetingService beepGreetingService(GreetingProperties properties) {
+        return new BeepGreetingService(properties.getText());
+    }
 }

components/library-autoconfigure/src/main/java/com/workshop/magic/config/MyCustomCondition.java

@@ -0,0 +1,16 @@
+package com.workshop.magic.config;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.context.annotation.Conditional;
+
+@Target({ElementType.TYPE, ElementType.METHOD})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Conditional({OnCustomCondition.class})
+@interface MyCustomCondition {
+}

components/library-autoconfigure/src/main/java/com/workshop/magic/config/OnCustomCondition.java

@@ -0,0 +1,22 @@
+package com.workshop.magic.config;
+
+import java.util.Locale;
+
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+
+class OnCustomCondition extends SpringBootCondition {
+    @Override
+    public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
+        String value = System.getProperty("my.custom.condition");
+        if (value == null) {
+            return ConditionOutcome.noMatch("No 'my.custom.condition' system property found");
+        }
+        if (value.toLowerCase(Locale.ROOT).equals("true")) {
+            return ConditionOutcome.match("'my.custom.condition' system property is true");
+        }
+        return ConditionOutcome.noMatch("'my.custom.condition' system property is '%s'".formatted(value));
+    }
+}