Hexagonal Architecture - brucedjyan@gmail.com

spring-boot-data/src/main/java/com/baeldung/adapters/FriendDAOAdapter.java

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+package com.baeldung.adapters;
+
+import com.baeldung.domain.Friend;
+import com.baeldung.ports.FriendDAOPort;
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+
+@Service
+public class FriendDAOAdapter implements FriendDAOPort {
+    @Override
+    public List<Friend> list(Long id) {
+        // Call external component to query friends data and convert the entities to friends domain
+        return null;
+    }
+}

spring-boot-data/src/main/java/com/baeldung/adapters/FriendUIAdapter.java

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+package com.baeldung.adapters;
+
+import com.baeldung.domain.Friend;
+import com.baeldung.ports.FriendUIPort;
+import com.baeldung.service.FriendService;
+import org.springframework.stereotype.Service;
+
+import javax.annotation.Resource;
+import java.util.List;
+import java.util.Map;
+
+@Service
+public class FriendUIAdapter implements FriendUIPort {
+    @Resource
+    private FriendService friendService;
+
+    @Override
+    public Map<String, List<Friend>> getFriends(Long id) {
+        return friendService.friends(id);
+    }
+}

spring-boot-data/src/main/java/com/baeldung/domain/Friend.java

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+package com.baeldung.domain;
+
+public class Friend {
+    private Long id;
+    private String name;
+    private Integer age;
+    private Long updateTime;
+    private String group;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+
+    public void setAge(Integer age) {
+        this.age = age;
+    }
+
+    public Long getUpdateTime() {
+        return updateTime;
+    }
+
+    public void setUpdateTime(Long updateTime) {
+        this.updateTime = updateTime;
+    }
+
+    public String getGroup() {
+        return group;
+    }
+
+    public void setGroup(String group) {
+        this.group = group;
+    }
+}

spring-boot-data/src/main/java/com/baeldung/ports/FriendDAOPort.java

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+package com.baeldung.ports;
+
+import com.baeldung.domain.Friend;
+
+import java.util.List;
+
+public interface FriendDAOPort {
+    List<Friend> list(Long id);
+}

spring-boot-data/src/main/java/com/baeldung/ports/FriendUIPort.java

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+package com.baeldung.ports;
+
+import com.baeldung.domain.Friend;
+
+import java.util.List;
+import java.util.Map;
+
+public interface FriendUIPort {
+    Map<String, List<Friend>> getFriends(Long id);
+}

spring-boot-data/src/main/java/com/baeldung/service/FriendService.java

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+package com.baeldung.service;
+
+import com.baeldung.domain.Friend;
+import com.baeldung.ports.FriendDAOPort;
+import org.springframework.stereotype.Service;
+
+import javax.annotation.Resource;
+import java.util.List;
+import java.util.Map;
+
+import static java.util.Comparator.comparingLong;
+import static java.util.stream.Collectors.groupingBy;
+
+@Service
+public class FriendService {
+    @Resource
+    private FriendDAOPort friendDAOPort;
+
+    public Map<String, List<Friend>> friends(Long id) {
+        List<Friend> friends = friendDAOPort.list(id);
+        return friends.stream()
+                .sorted(comparingLong(Friend::getUpdateTime).reversed())
+                .collect(groupingBy(Friend::getGroup));
+    }
+}