loading json props

spring-boot/src/main/java/org/baeldung/properties/ConfigPropertiesDemoApplication.java

@@ -1,13 +1,15 @@
 package org.baeldung.properties;
 
-import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
 import org.springframework.context.annotation.ComponentScan;
 
 @EnableAutoConfiguration
-@ComponentScan(basePackageClasses = ConfigProperties.class)
+@ComponentScan(basePackageClasses = { ConfigProperties.class, JsonProperties.class, CustomJsonProperties.class })
 public class ConfigPropertiesDemoApplication {
     public static void main(String[] args) {
-        SpringApplication.run(ConfigPropertiesDemoApplication.class);
+        new SpringApplicationBuilder(ConfigPropertiesDemoApplication.class).initializers(new JsonPropertyContextInitializer())
+            .run();
     }
+
 }

spring-boot/src/main/java/org/baeldung/properties/CustomJsonProperties.java

@@ -0,0 +1,71 @@
+package org.baeldung.properties;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@ConfigurationProperties(prefix = "custom")
+public class CustomJsonProperties {
+
+    private String host;
+
+    private int port;
+
+    private boolean resend;
+
+    private Person sender;
+
+    public static class Person {
+
+        private String name;
+        private String address;
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public String getAddress() {
+            return address;
+        }
+
+        public void setAddress(String address) {
+            this.address = address;
+        }
+    }
+
+    public String getHost() {
+        return host;
+    }
+
+    public void setHost(String host) {
+        this.host = host;
+    }
+
+    public int getPort() {
+        return port;
+    }
+
+    public void setPort(int port) {
+        this.port = port;
+    }
+
+    public boolean isResend() {
+        return resend;
+    }
+
+    public void setResend(boolean resend) {
+        this.resend = resend;
+    }
+
+    public Person getSender() {
+        return sender;
+    }
+
+    public void setSender(Person sender) {
+        this.sender = sender;
+    }
+}

spring-boot/src/main/java/org/baeldung/properties/JsonProperties.java

@@ -0,0 +1,64 @@
+package org.baeldung.properties;
+
+import java.util.LinkedHashMap;
+import java.util.List;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.PropertySource;
+
+@Configuration
+@PropertySource(value = "classpath:configprops.json", factory = JsonPropertySourceFactory.class)
+@ConfigurationProperties
+public class JsonProperties {
+
+    private String host;
+
+    private int port;
+
+    private boolean resend;
+
+    private List<String> topics;
+
+    private LinkedHashMap<String, ?> sender;
+
+    public LinkedHashMap<String, ?> getSender() {
+        return sender;
+    }
+
+    public void setSender(LinkedHashMap<String, ?> sender) {
+        this.sender = sender;
+    }
+
+    public List<String> getTopics() {
+        return topics;
+    }
+
+    public void setTopics(List<String> topics) {
+        this.topics = topics;
+    }
+
+    public int getPort() {
+        return port;
+    }
+
+    public void setPort(int port) {
+        this.port = port;
+    }
+
+    public boolean isResend() {
+        return resend;
+    }
+
+    public void setResend(boolean resend) {
+        this.resend = resend;
+    }
+
+    public String getHost() {
+        return host;
+    }
+
+    public void setHost(String host) {
+        this.host = host;
+    }
+}

spring-boot/src/main/java/org/baeldung/properties/JsonPropertyContextInitializer.java

@@ -0,0 +1,68 @@
+package org.baeldung.properties;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.PropertySource;
+import org.springframework.core.io.Resource;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class JsonPropertyContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
+
+    private final static String CUSTOM_PREFIX = "custom.";
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
+        try {
+            Resource resource = configurableApplicationContext.getResource("classpath:configpropscustom.json");
+            Map readValue = new ObjectMapper().readValue(resource.getInputStream(), Map.class);
+            Set<Map.Entry> set = readValue.entrySet();
+            List<MapPropertySource> propertySources = convertEntrySet(set, Optional.empty());
+            for (PropertySource propertySource : propertySources) {
+                configurableApplicationContext.getEnvironment()
+                    .getPropertySources()
+                    .addFirst(propertySource);
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private static List<MapPropertySource> convertEntrySet(Set<Map.Entry> entrySet, Optional<String> parentKey) {
+        return entrySet.stream()
+            .map((Map.Entry e) -> convertToPropertySourceList(e, parentKey))
+            .flatMap(Collection::stream)
+            .collect(Collectors.toList());
+    }
+
+    private static List<MapPropertySource> convertToPropertySourceList(Map.Entry e, Optional<String> parentKey) {
+        String key = parentKey.map(s -> s + ".")
+            .orElse("") + (String) e.getKey();
+        Object value = e.getValue();
+        return covertToPropertySourceList(key, value);
+    }
+
+    @SuppressWarnings("unchecked")
+    private static List<MapPropertySource> covertToPropertySourceList(String key, Object value) {
+        if (value instanceof LinkedHashMap) {
+            LinkedHashMap map = (LinkedHashMap) value;
+            Set<Map.Entry> entrySet = map.entrySet();
+            return convertEntrySet(entrySet, Optional.ofNullable(key));
+        }
+        String finalKey = CUSTOM_PREFIX + key;
+        return Collections.singletonList(new MapPropertySource(finalKey, Collections.singletonMap(finalKey, value)));
+    }
+
+}

spring-boot/src/main/java/org/baeldung/properties/JsonPropertySourceFactory.java

@@ -0,0 +1,20 @@
+package org.baeldung.properties;
+
+import java.io.IOException;
+import java.util.Map;
+
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.io.support.EncodedResource;
+import org.springframework.core.io.support.PropertySourceFactory;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class JsonPropertySourceFactory implements PropertySourceFactory {
+
+    @Override
+    public org.springframework.core.env.PropertySource<?> createPropertySource(String name, EncodedResource resource) throws IOException {
+        Map readValue = new ObjectMapper().readValue(resource.getInputStream(), Map.class);
+        return new MapPropertySource("json-property", readValue);
+    }
+
+}

spring-boot/src/main/resources/configprops.json

@@ -0,0 +1,10 @@
+{
+  "host" : "mailer@mail.com",
+  "port" : 9090,
+  "resend" : true,
+  "topics" : ["spring", "boot"],
+  "sender" : {
+    "name": "sender",
+    "address": "street"
+  }
+}

spring-boot/src/main/resources/configpropscustom.json

@@ -0,0 +1,9 @@
+{
+  "host" : "mailer.custom@mail.com",
+  "port" : 8081,
+  "resend" : true,
+  "sender" : {
+    "name": "sender.custom",
+    "address": "street.custom"
+  }
+}

spring-boot/src/test/java/org/baeldung/properties/JsonPropertiesIntegrationTest.java

@@ -0,0 +1,59 @@
+package org.baeldung.properties;
+
+import java.util.Arrays;
+
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@ContextConfiguration(classes = ConfigPropertiesDemoApplication.class, initializers = JsonPropertyContextInitializer.class)
+public class JsonPropertiesIntegrationTest {
+
+    @Autowired
+    private JsonProperties jsonProperties;
+
+    @Autowired
+    private CustomJsonProperties customJsonProperties;
+
+    @Test
+    public void givenJsonPropertySource_whenPropertySourceFactoryUsed_thenLoadFlatValues() {
+        Assert.assertEquals("mailer@mail.com", jsonProperties.getHost());
+        Assert.assertEquals(9090, jsonProperties.getPort());
+        Assert.assertTrue(jsonProperties.isResend());
+    }
+
+    @Test
+    public void givenJsonPropertySource_whenPropertySourceFactoryUsed_thenLoadListValues() {
+        Assert.assertThat(jsonProperties.getTopics(), Matchers.is(Arrays.asList("spring", "boot")));
+    }
+
+    @Test
+    public void givenJsonPropertySource_whenPropertySourceFactoryUsed_thenNestedValuesLoadedAsMap() {
+        Assert.assertEquals("sender", jsonProperties.getSender()
+            .get("name"));
+        Assert.assertEquals("street", jsonProperties.getSender()
+            .get("address"));
+    }
+
+    @Test
+    public void givenCustomJsonPropertySource_whenLoadedIntoEnvironment_thenFlatValuesPopulated() {
+        Assert.assertEquals("mailer.custom@mail.com", customJsonProperties.getHost());
+        Assert.assertEquals(8081, customJsonProperties.getPort());
+        Assert.assertTrue(customJsonProperties.isResend());
+    }
+
+    @Test
+    public void givenCustomJsonPropertySource_whenLoadedIntoEnvironment_thenValuesLoadedIntoClassObject() {
+        Assert.assertNotNull(customJsonProperties.getSender());
+        Assert.assertEquals("sender.custom", customJsonProperties.getSender()
+            .getName());
+        Assert.assertEquals("street.custom", customJsonProperties.getSender()
+            .getAddress());
+    }
+
+}