a spring module with an initial example of a circular dependency that…

… spring can't figure out without help

pom.xml

@@ -40,6 +40,7 @@
         <module>guava-concatenate-streams</module>
         <module>spring-data</module>
         <module>spring-mvc</module>
+        <module>spring</module>
     </modules>
     <properties>
 <!--

spring/pom.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>testbed</artifactId>
+        <groupId>testbed</groupId>
+        <version>1.1-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>spring</artifactId>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-core</artifactId>
+            <version>3.2.1.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-beans</artifactId>
+            <version>3.2.1.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-context</artifactId>
+            <version>3.2.1.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>1.0.9</version>
+        </dependency>
+        <dependency>
+            <groupId>cglib</groupId>
+            <artifactId>cglib</artifactId>
+            <version>2.2</version>
+        </dependency>
+    </dependencies>
+</project>

spring/src/main/java/rds/spring/CircularDependencies.java

@@ -0,0 +1,51 @@
+package rds.spring;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.DependsOn;
+import org.springframework.stereotype.Component;
+
+/**
+ * Created with IntelliJ IDEA.
+ * User: ryan
+ * Date: 3/3/13
+ * Time: 10:49 PM
+ */
+public class CircularDependencies {
+    @Component("a")
+    @DependsOn("b") // Without this annotation, Spring tries to create an A first and fails when creating the B that depends on the A that's in creation.
+    public static class A {
+        @Autowired
+        public A(B b) {
+        }
+    }
+
+    @Component("b")
+    public static class B {
+        private A a;
+
+        public B() {
+        }
+
+        @Autowired
+        public void setA(A a) {
+            this.a = a;
+        }
+    }
+
+    @Configuration
+    @ComponentScan
+    static class Config {
+    }
+
+    public static void main(String[] args) {
+        AnnotationConfigApplicationContext context =
+                new AnnotationConfigApplicationContext(Config.class);
+        A a = context.getBean(A.class);
+        B b = context.getBean(B.class);
+        System.out.println(a);
+        System.out.println(b);
+    }
+}