WIP with example

Author: jabrena

.cursor/rules/301-frameworks-spring-boot-core.mdc

@@ -18,6 +18,7 @@ These guidelines are built upon the following core principles:
 
 ## Table of contents
 
+- Rule 0: Spring Boot Main Application Class
 - Rule 1: Main Spring Boot Annotations Usage
 - Rule 2: Bean Definition and Management
 - Rule 3: Configuration Classes and Properties
@@ -27,6 +28,75 @@ These guidelines are built upon the following core principles:
 - Rule 7: Bean Minimization and Composition
 - Rule 8: Scheduled Tasks and Background Processing
 
+## Rule 0: Spring Boot Main Application Class
+
+Title: Create a Proper Spring Boot Main Application Class
+Description: Every Spring Boot application should have a main application class annotated with @SpringBootApplication. This class serves as the entry point and configuration root, combining @Configuration, @EnableAutoConfiguration, and @ComponentScan annotations.
+
+**Good example:**
+
+```java
+@SpringBootApplication
+public class MainApplication {
+    
+    public static void main(String[] args) {
+        SpringApplication.run(MainApplication.class, args);
+    }
+}
+
+// For more complex scenarios with custom configuration
+@SpringBootApplication(
+    scanBasePackages = {
+        "com.company.app.controller",
+        "com.company.app.service", 
+        "com.company.app.repository",
+        "com.company.app.config"
+    },
+    exclude = {
+        DataSourceAutoConfiguration.class,
+        SecurityAutoConfiguration.class
+    }
+)
+```
+
+**Bad Example:**
+
+```java
+// Missing @SpringBootApplication annotation
+public class MainApplication {
+    public static void main(String[] args) {
+        // Manual Spring context setup instead of SpringApplication.run()
+        ApplicationContext context = new AnnotationConfigApplicationContext();
+        // Manual configuration - loses Spring Boot benefits
+    }
+}
+
+// Using individual annotations instead of @SpringBootApplication
+@Configuration
+@EnableAutoConfiguration  
+@ComponentScan
+public class MainApplication { // Verbose and error-prone
+    public static void main(String[] args) {
+        SpringApplication.run(MainApplication.class, args);
+    }
+}
+
+// Poor naming and structure
+@SpringBootApplication
+public class App { // Non-descriptive name
+    
+    @Autowired
+    private UserService userService; // Business logic in main class
+    
+    public static void main(String[] args) {
+        SpringApplication.run(App.class, args);
+        
+        // Business logic in main method - should be in separate components
+        System.out.println("Processing users...");
+    }
+}
+```
+
 ## Rule 1: Main Spring Boot Annotations Usage
 
 Title: Use Appropriate Spring Boot Annotations for Component Definition

.github/workflows/maven.yaml

@@ -15,4 +15,6 @@ jobs:
           distribution: 'graalvm' # See 'Supported distributions' for available options
           java-version: '24'
       - name: Maven build
-        run: cd examples/maven-demo && ./mvnw --batch-mode --no-transfer-progress verify --file pom.xml
+        run: cd examples/maven-demo && ./mvnw --batch-mode --no-transfer-progress verify --file pom.xml
+      - name: Spring Boot build
+        run: cd examples/spring-boot-demo/implementation && ./mvnw --batch-mode --no-transfer-progress verify --file pom.xml

examples/README.md

@@ -2,4 +2,10 @@
 
 | Example  | Notes |
 |----------|-------|
-| 1. Maven demo | Simple Maven demo generated with `jbang setup@jabrena init --maven`. Used to test the behaviour of Cursor rules for Java. |
+| Maven demo | Simple Maven demo generated with `jbang setup@jabrena init --maven`. Used to test the behaviour of Cursor rules for Java. |
+| Spring Boot demo | Simple Maven demo generated with `jbang setup@jabrena init --spring-boot`. Used to test the behaviour of Cursor rules for Java & Spring Boot. |
+
+
+## References
+
+- https://github.com/jabrena/spring-boot-relational-database-poc/

examples/spring-boot-demo/implementation/.gitattributes

@@ -0,0 +1,2 @@
+/mvnw text eol=lf
+*.cmd text eol=crlf

examples/spring-boot-demo/implementation/.gitignore

@@ -0,0 +1,33 @@
+HELP.md
+target/
+.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

examples/spring-boot-demo/implementation/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,19 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+wrapperVersion=3.3.2
+distributionType=only-script
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.10/apache-maven-3.9.10-bin.zip