BAEL-5664 code for the using environment varibales in application.properties article

spring-core-6/pom.xml

@@ -1,7 +1,7 @@
 <?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">
+         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">
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>com.baeldung</groupId>
@@ -10,23 +10,36 @@
     <name>spring-core-6</name>
     <url>http://www.baeldung.com</url>
 
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.source>11</maven.compiler.source>
         <maven.compiler.target>11</maven.compiler.target>
+        <spring.boot.version>2.7.2</spring.boot.version>
     </properties>
 
     <dependencies>
         <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <version>4.11</version>
-            <scope>test</scope>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+            <version>${spring.boot.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-starter-web</artifactId>
-            <version>2.0.0.RELEASE</version>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <version>${spring.boot.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit-jupiter.version}</version>
+            <scope>test</scope>
         </dependency>
     </dependencies>
 

spring-core-6/src/main/java/com/baeldung/envvariables/BaeldungProperties.java

@@ -0,0 +1,20 @@
+package com.baeldung.envvariables.valueinjection;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.stereotype.Component;
+
+@Component
+@ConfigurationProperties(prefix = "baeldung")
+public class BaeldungProperties {
+
+    private String presentation;
+
+    public String getPresentation() {
+        return presentation;
+    }
+
+    public void setPresentation(String presentation) {
+        this.presentation = presentation;
+    }
+
+}

spring-core-6/src/main/java/com/baeldung/envvariables/MyController.java

@@ -0,0 +1,60 @@
+package com.baeldung.envvariables.valueinjection;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.core.env.Environment;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class MyController {
+
+    @Value("${environment.name}")
+    private String environmentName;
+
+    @Value("${java.home.and.environment}")
+    private String javaHomeAndEnvironmentName;
+
+    @Value("${thispropertydoesnotexist}")
+    private String nonExistentProperty;
+
+    @Value("${baeldung.presentation}")
+    private String baeldungPresentation;
+
+    @Autowired
+    private Environment environment;
+
+    @Autowired
+    private BaeldungProperties baeldungProperties;
+
+    @GetMapping("/environment_name")
+    String getEnvironmentName_FromEnvironmentVariables() {
+        return environmentName;
+    }
+
+    @GetMapping("/java_home_and_environment")
+    String getJavaHomeAndEnvironmentName_FromEnvironmentVariables() {
+        return javaHomeAndEnvironmentName;
+    }
+
+    @GetMapping("non_existent_property")
+    String getNonexistentProperty_FromEnvironmentVariables() {
+        return nonExistentProperty;
+    }
+
+    @GetMapping("baeldung_presentation_from_value")
+    String getBaeldungPresentation_FromValue() {
+        return baeldungPresentation;
+    }
+
+    @GetMapping("baeldung_presentation_from_environment")
+    String getBaeldungPresentation_FromEnvironment() {
+        return environment.getProperty("baeldung.presentation");
+    }
+
+    @GetMapping("baeldung_configuration_properties")
+    String getBaeldungPresentation_FromConfigurationProperties() {
+        return baeldungProperties.getPresentation();
+    }
+
+}

spring-core-6/src/main/resources/application.properties

@@ -0,0 +1,4 @@
+environment.name=${OS}
+java.home.and.environment=${JAVA_HOME}+${OS}
+not.existing.system.property=${thispropertydoesnotexist}
+baeldung.presentation=${HELLO_BAELDUNG}. Java is installed in the folder: ${JAVA_HOME}

spring-core-6/src/test/java/com/baeldung/envvariables/MyControllerIntegrationTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.envvariables.valueinjection;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.web.servlet.MockMvc;
+
+@SpringBootTest(classes = MyController.class)
+@AutoConfigureMockMvc
+public class MyControllerIntegrationTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    /** NB : these tests are commented out because they are environment dependent
+     * If you want to run one of them on your machine, follow the instruction above it
+     *
+     * expects the value of your system environment property 'OS' (it is already defined at least in Windows_NT)
+     @Test void givenExistingSystemProperty_whenInjected_thenHasSystemPropertyValue() throws Exception {
+     mockMvc.perform(get("/environment_name"))
+     .andExpect(content().string(equalTo("Windows_NT")));
+     }
+
+      * expects the value of the JAVA_HOME environment variable (you need to define it if you haven't yet), with a + and the 'OS' environment property in the end
+     @Test void givenCombinationOfSystemPropertyAndEnvironmentVariable_whenInjected_thenHasExpectedValue() throws Exception {
+     mockMvc.perform(get("/java_home_and_environment"))
+     .andExpect(content().string(equalTo("C:\\Program Files\\Java\\jdk-11.0.14+Windows_NT")));
+     }
+
+      * expects the content to be ${thispropertydoesnotexist} ; if you have defined an environment property called thispropertydoesnotexist, it would fail
+     @Test void givenNonExistentProperty_whenInjected_thenKeepsTheStringValue() throws Exception {
+     mockMvc.perform(get("/non_existent_property"))
+     .andExpect(content().string(equalTo("${thispropertydoesnotexist}")));
+     }
+     */
+}