커스톰 @conditional과 Condition 도입

build.gradle

@@ -13,8 +13,7 @@ repositories {
 }
 
 dependencies {
-	implementation 'org.springframework.boot:spring-boot-starter-web'
-	implementation 'org.springframework.boot:spring-boot-starter-jetty'
+	implementation('org.springframework.boot:spring-boot-starter-web')
 	testImplementation 'org.springframework.boot:spring-boot-starter-test'
 }
 

src/main/java/tobyspring/config/ConditionalMyOnClass.java

@@ -0,0 +1,15 @@
+package tobyspring.config;
+
+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;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.TYPE, ElementType.METHOD})
+@Conditional(MyOnClassCondition.class)
+public @interface ConditionalMyOnClass {
+    String value();
+}

src/main/java/tobyspring/config/MyOnClassCondition.java

@@ -0,0 +1,17 @@
+package tobyspring.config;
+
+import org.springframework.context.annotation.Condition;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+import org.springframework.util.ClassUtils;
+
+import java.util.Map;
+
+public class MyOnClassCondition implements Condition {
+    @Override
+    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
+        Map<String, Object> attrs = metadata.getAnnotationAttributes(ConditionalMyOnClass.class.getName());
+        String value = (String) attrs.get("value");
+        return ClassUtils.isPresent(value, context.getClassLoader());
+    }
+}

src/main/java/tobyspring/config/autoconfig/JettyWebServerConfig.java

@@ -8,20 +8,15 @@
 import org.springframework.context.annotation.ConditionContext;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.core.type.AnnotatedTypeMetadata;
+import org.springframework.util.ClassUtils;
+import tobyspring.config.ConditionalMyOnClass;
 import tobyspring.config.MyAutoConfiguration;
 
 @MyAutoConfiguration
-@Conditional(JettyWebServerConfig.JettyCondition.class)
+@ConditionalMyOnClass("org.eclipse.jetty.server.Server")
 public class JettyWebServerConfig {
     @Bean("jettyWebServerFactory")
     public ServletWebServerFactory servletWebServerFactory() {
         return new JettyServletWebServerFactory();
     }
-
-    static class JettyCondition implements Condition {
-        @Override
-        public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
-            return false;
-        }
-    }
 }

src/main/java/tobyspring/config/autoconfig/TomcatWebServerConfig.java

@@ -4,20 +4,15 @@
 import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
 import org.springframework.context.annotation.*;
 import org.springframework.core.type.AnnotatedTypeMetadata;
+import org.springframework.util.ClassUtils;
+import tobyspring.config.ConditionalMyOnClass;
 import tobyspring.config.MyAutoConfiguration;
 
 @MyAutoConfiguration
-@Conditional(TomcatWebServerConfig.TomcatCondition.class)
+@ConditionalMyOnClass("org.apache.catalina.startup.Tomcat")
 public class TomcatWebServerConfig {
     @Bean("tomcatWebServerFactory")
     public ServletWebServerFactory servletWebServerFactory() {
         return new TomcatServletWebServerFactory();
     }
-
-    static class TomcatCondition implements Condition {
-        @Override
-        public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
-            return false;
-        }
-    }
 }