moving between packages

spring-boot/src/main/java/com/baeldung/properties/ConfigProperties.java

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+package com.baeldung.properties;
+
+import java.util.List;
+import java.util.Map;
+
+import javax.validation.constraints.Max;
+import javax.validation.constraints.Min;
+import javax.validation.constraints.Pattern;
+
+import org.hibernate.validator.constraints.Length;
+import org.hibernate.validator.constraints.NotBlank;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.PropertySource;
+import org.springframework.validation.annotation.Validated;
+
+@Configuration
+@PropertySource("classpath:configprops.properties")
+@ConfigurationProperties(prefix = "mail")
+@Validated
+public class ConfigProperties {
+
+    @Validated
+    public static class Credentials {
+
+        @Length(max = 4, min = 1)
+        private String authMethod;
+        private String username;
+        private String password;
+
+        public String getAuthMethod() {
+            return authMethod;
+        }
+
+        public void setAuthMethod(String authMethod) {
+            this.authMethod = authMethod;
+        }
+
+        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;
+        }
+    }
+
+    @NotBlank
+    private String host;
+
+    @Min(1025)
+    @Max(65536)
+    private int port;
+
+    @Pattern(regexp = "^[a-z0-9._%+-]+@[a-z0-9.-]+\\.[a-z]{2,6}$")
+    private String from;
+
+    private Credentials credentials;
+    private List<String> defaultRecipients;
+    private Map<String, String> additionalHeaders;
+
+    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 String getFrom() {
+        return from;
+    }
+
+    public void setFrom(String from) {
+        this.from = from;
+    }
+
+    public Credentials getCredentials() {
+        return credentials;
+    }
+
+    public void setCredentials(Credentials credentials) {
+        this.credentials = credentials;
+    }
+
+    public List<String> getDefaultRecipients() {
+        return defaultRecipients;
+    }
+
+    public void setDefaultRecipients(List<String> defaultRecipients) {
+        this.defaultRecipients = defaultRecipients;
+    }
+
+    public Map<String, String> getAdditionalHeaders() {
+        return additionalHeaders;
+    }
+
+    public void setAdditionalHeaders(Map<String, String> additionalHeaders) {
+        this.additionalHeaders = additionalHeaders;
+    }
+}

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

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

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

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+package com.baeldung.properties;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.stereotype.Component;
+
+@Component
+@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/com/baeldung/properties/JsonProperties.java

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+package com.baeldung.properties;
+
+import java.util.LinkedHashMap;
+import java.util.List;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.PropertySource;
+import org.springframework.stereotype.Component;
+
+@Component
+@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/com/baeldung/properties/JsonPropertyContextInitializer.java

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+package com.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:configprops.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/com/baeldung/properties/JsonPropertySourceFactory.java

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+package com.baeldung.properties;
+
+import java.io.IOException;
+import java.util.Map;
+
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.PropertySource;
+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 PropertySource<?> createPropertySource(String name, EncodedResource resource) throws IOException {
+        Map readValue = new ObjectMapper().readValue(resource.getInputStream(), Map.class);
+        return new MapPropertySource("json-property", readValue);
+    }
+
+}