Bael 2997 spring boot configuration processor (#7376)

* BAEL-2997: Adding spring boot configuration processor dependency.

* BAEL-2997: Added examples for spring boot configuration processor, simple and nested properties.

* BAEL-2997: Fixed the identation

* BAEL-2997: Formatted the added dependencies

* BAEL-2997: Added version for configuration-processor dependency.

spring-boot-autoconfiguration/pom.xml

@@ -38,6 +38,19 @@
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
         </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-configuration-processor</artifactId>
+            <version>2.1.6.RELEASE</version>
+            <optional>true</optional>
+        </dependency>
+
+        <dependency>
+            <groupId>org.hsqldb</groupId>
+            <artifactId>hsqldb</artifactId>
+            <scope>runtime</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -50,12 +63,10 @@
         </resources>
 
         <plugins>
-
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-war-plugin</artifactId>
             </plugin>
-
         </plugins>
 
     </build>

spring-boot-autoconfiguration/src/main/java/com/baeldung/autoconfiguration/annotationprocessor/AnnotationProcessorApplication.java

@@ -0,0 +1,15 @@
+package com.baeldung.autoconfiguration.annotationprocessor;
+
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.context.annotation.ComponentScan;
+
+import com.baeldung.autoconfiguration.MySQLAutoconfiguration;
+
+@EnableAutoConfiguration(exclude = { MySQLAutoconfiguration.class})
+@ComponentScan(basePackageClasses = {DatabaseProperties.class})
+public class AnnotationProcessorApplication {
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(AnnotationProcessorApplication.class).run();
+    }
+}

spring-boot-autoconfiguration/src/main/java/com/baeldung/autoconfiguration/annotationprocessor/DatabaseProperties.java

@@ -0,0 +1,73 @@
+package com.baeldung.autoconfiguration.annotationprocessor;
+
+import javax.validation.constraints.Max;
+import javax.validation.constraints.Min;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@ConfigurationProperties(prefix = "database")
+public class DatabaseProperties {
+
+    public static class Server {
+
+        /**
+         * The IP of the database server
+         */
+        private String ip;
+
+        /**
+         * The Port of the database server.
+         * The Default value is 443.
+         * The allowed values are in the range 400-4000.
+         */
+        @Min(400)
+        @Max(800)
+        private int port = 443;
+
+        public String getIp() {
+            return ip;
+        }
+
+        public void setIp(String ip) {
+            this.ip = ip;
+        }
+
+        public int getPort() {
+            return port;
+        }
+
+        public void setPort(int port) {
+            this.port = port;
+        }
+    }
+
+    private String username;
+    private String password;
+    private Server server;
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public Server getServer() {
+        return server;
+    }
+
+    public void setServer(Server server) {
+        this.server = server;
+    }
+}

spring-boot-autoconfiguration/src/test/java/com/baeldung/autoconfiguration/annotationprocessor/DatabasePropertiesIntegrationTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.autoconfiguration.annotationprocessor;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.TestPropertySource;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = AnnotationProcessorApplication.class)
+@TestPropertySource("classpath:databaseproperties-test.properties")
+public class DatabasePropertiesIntegrationTest {
+
+    @Autowired
+    private DatabaseProperties databaseProperties;
+
+    @Test
+    public void whenSimplePropertyQueriedThenReturnsPropertyValue() throws Exception {
+        Assert.assertEquals("Incorrectly bound Username property", "baeldung", databaseProperties.getUsername());
+        Assert.assertEquals("Incorrectly bound Password property", "password", databaseProperties.getPassword());
+    }
+    
+    @Test
+    public void whenNestedPropertyQueriedThenReturnsPropertyValue() throws Exception {
+    	Assert.assertEquals("Incorrectly bound Server IP nested property", "127.0.0.1", databaseProperties.getServer().getIp());
+        Assert.assertEquals("Incorrectly bound Server Port nested property", 3306, databaseProperties.getServer().getPort());
+    }   
+
+}

spring-boot-autoconfiguration/src/test/resources/databaseproperties-test.properties

@@ -0,0 +1,7 @@
+#Simple Properties
+database.username=baeldung
+database.password=password
+
+#Nested Properties
+database.server.ip=127.0.0.1
+database.server.port=3306