From 7eb74160f1bd95b8c817b46e087e2267b8aabf0b Mon Sep 17 00:00:00 2001
From: Mher Baghinyan <mbaghinyan@gmail.com>
Date: Sat, 17 Mar 2018 13:30:44 +0400
Subject: [PATCH] @Lazy annotation (#3809)

---
 .../java/com/baeldung/lazy/AppConfig.java     | 23 ++++++++++++
 .../src/main/java/com/baeldung/lazy/City.java | 13 +++++++
 .../main/java/com/baeldung/lazy/Country.java  |  8 ++++
 .../main/java/com/baeldung/lazy/Region.java   | 19 ++++++++++
 .../baeldung/Lazy/LazyAnnotationUnitTest.java | 37 +++++++++++++++++++
 5 files changed, 100 insertions(+)
 create mode 100644 spring-core/src/main/java/com/baeldung/lazy/AppConfig.java
 create mode 100644 spring-core/src/main/java/com/baeldung/lazy/City.java
 create mode 100644 spring-core/src/main/java/com/baeldung/lazy/Country.java
 create mode 100644 spring-core/src/main/java/com/baeldung/lazy/Region.java
 create mode 100644 spring-core/src/test/java/com/baeldung/Lazy/LazyAnnotationUnitTest.java

diff --git a/spring-core/src/main/java/com/baeldung/lazy/AppConfig.java b/spring-core/src/main/java/com/baeldung/lazy/AppConfig.java
new file mode 100644
index 0000000000..0d76876cd8
--- /dev/null
+++ b/spring-core/src/main/java/com/baeldung/lazy/AppConfig.java
@@ -0,0 +1,23 @@
+package com.baeldung.lazy;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Lazy;
+
+@Lazy
+@Configuration
+@ComponentScan(basePackages = "com.baeldung.lazy")
+public class AppConfig {
+
+    @Lazy
+    @Bean
+    public Region getRegion(){
+        return new Region();
+    }
+
+    @Bean
+    public Country getCountry(){
+        return new Country();
+    }
+}
diff --git a/spring-core/src/main/java/com/baeldung/lazy/City.java b/spring-core/src/main/java/com/baeldung/lazy/City.java
new file mode 100644
index 0000000000..27073b5fe7
--- /dev/null
+++ b/spring-core/src/main/java/com/baeldung/lazy/City.java
@@ -0,0 +1,13 @@
+package com.baeldung.lazy;
+
+import org.springframework.context.annotation.Lazy;
+import org.springframework.stereotype.Component;
+
+@Lazy
+@Component
+public class City {
+
+    public City() {
+        System.out.println("City bean initialized");
+    }
+}
diff --git a/spring-core/src/main/java/com/baeldung/lazy/Country.java b/spring-core/src/main/java/com/baeldung/lazy/Country.java
new file mode 100644
index 0000000000..dbac1a2bdc
--- /dev/null
+++ b/spring-core/src/main/java/com/baeldung/lazy/Country.java
@@ -0,0 +1,8 @@
+package com.baeldung.lazy;
+
+public class Country {
+
+    public Country() {
+        System.out.println("Country bean initialized");
+    }
+}
diff --git a/spring-core/src/main/java/com/baeldung/lazy/Region.java b/spring-core/src/main/java/com/baeldung/lazy/Region.java
new file mode 100644
index 0000000000..5211e5d622
--- /dev/null
+++ b/spring-core/src/main/java/com/baeldung/lazy/Region.java
@@ -0,0 +1,19 @@
+package com.baeldung.lazy;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Lazy;
+
+public class Region {
+
+    @Lazy
+    @Autowired
+    private City city;
+
+    public Region() {
+        System.out.println("Region bean initialized");
+    }
+
+    public City getCityInstance() {
+        return city;
+    }
+}
diff --git a/spring-core/src/test/java/com/baeldung/Lazy/LazyAnnotationUnitTest.java b/spring-core/src/test/java/com/baeldung/Lazy/LazyAnnotationUnitTest.java
new file mode 100644
index 0000000000..187d573557
--- /dev/null
+++ b/spring-core/src/test/java/com/baeldung/Lazy/LazyAnnotationUnitTest.java
@@ -0,0 +1,37 @@
+package com.baeldung.Lazy;
+
+import com.baeldung.lazy.AppConfig;
+import com.baeldung.lazy.Country;
+import com.baeldung.lazy.Region;
+import org.junit.Test;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+
+public class LazyAnnotationUnitTest {
+
+    @Test
+    public void givenLazyAnnotation_whenConfigClass_thenLazyAll() {
+        // Add @Lazy to AppConfig.class while testing
+        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+        ctx.register(AppConfig.class);
+        ctx.refresh();
+        ctx.getBean(Region.class);
+        ctx.getBean(Country.class);
+    }
+
+    @Test
+    public void givenLazyAnnotation_whenAutowire_thenLazyBean() {
+        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+        ctx.register(AppConfig.class);
+        ctx.refresh();
+        Region region = ctx.getBean(Region.class);
+        region.getCityInstance();
+    }
+
+    @Test
+    public void givenLazyAnnotation_whenBeanConfig_thenLazyBean() {
+        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+        ctx.register(AppConfig.class);
+        ctx.refresh();
+        ctx.getBean(Region.class);
+    }
+}