[BAEL-4955] The DTO pattern (#11166)

* [BAEL-4955] The DTO pattern

* Fix encrypt logic

* Add tests

* Add tests

* Move packages

design-patterns/README.md

@@ -0,0 +1,5 @@
+## Article related
+
+- [The DTO Pattern (Data Transfer Object)]()
+
+

design-patterns/dto-pattern/pom.xml

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+<?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">
+
+    <groupId>com.baeldung.designpatterns.dtopattern</groupId>
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>dto-pattern</artifactId>
+    <name>dto-pattern</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-2</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-2</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <encoding>UTF-8</encoding>
+    </properties>
+
+</project>

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/Main.java

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+package com.baeldung.designpatterns.dtopattern;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Main {
+    public static void main(String[] args) {
+        SpringApplication.run(Main.class, args);
+    }
+}
+

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/api/Mapper.java

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+package com.baeldung.designpatterns.dtopattern.api;
+
+import com.baeldung.designpatterns.dtopattern.domain.Role;
+import com.baeldung.designpatterns.dtopattern.domain.User;
+import org.springframework.stereotype.Component;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.util.stream.Collectors.toList;
+
+@Component
+class Mapper {
+    public UserDTO toDto(User user) {
+        String name = user.getName();
+        List<String> roles = user
+                .getRoles()
+                .stream()
+                .map(Role::getName)
+                .collect(toList());
+
+        return new UserDTO(name, roles);
+    }
+
+    public User toUser(UserCreationDTO userDTO) {
+        return new User(userDTO.getName(), userDTO.getPassword(), new ArrayList<>());
+    }
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/api/UserController.java

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+package com.baeldung.designpatterns.dtopattern.api;
+
+import com.baeldung.designpatterns.dtopattern.domain.RoleService;
+import com.baeldung.designpatterns.dtopattern.domain.User;
+import com.baeldung.designpatterns.dtopattern.domain.UserService;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+import static java.util.stream.Collectors.toList;
+
+@RestController
+@RequestMapping("/users")
+class UserController {
+
+    private UserService userService;
+    private RoleService roleService;
+    private Mapper mapper;
+
+    public UserController(UserService userService,  RoleService roleService, Mapper mapper) {
+        this.userService = userService;
+        this.roleService = roleService;
+        this.mapper = mapper;
+    }
+
+    @GetMapping
+    @ResponseBody
+    public List<UserDTO> getUsers() {
+        return userService.getAll()
+            .stream()
+            .map(mapper::toDto)
+            .collect(toList());
+    }
+
+
+    @PostMapping
+    @ResponseBody
+    public UserIdDTO create(@RequestBody UserCreationDTO userDTO) {
+        User user = mapper.toUser(userDTO);
+
+        userDTO.getRoles()
+                .stream()
+                .map(role -> roleService.getOrCreate(role))
+                .forEach(user::addRole);
+
+        userService.save(user);
+
+        return new UserIdDTO(user.getId());
+    }
+
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/api/UserCreationDTO.java

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+package com.baeldung.designpatterns.dtopattern.api;
+
+import java.util.List;
+
+public class UserCreationDTO {
+
+    private String name;
+    private String password;
+    private List<String> roles;
+
+    UserCreationDTO() {}
+
+    public String getName() {
+        return name;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public List<String> getRoles() {
+        return roles;
+    }
+
+    void setName(String name) {
+        this.name = name;
+    }
+
+    void setPassword(String password) {
+        this.password = password;
+    }
+
+    void setRoles(List<String> roles) {
+        this.roles = roles;
+    }
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/api/UserDTO.java

@@ -0,0 +1,22 @@
+package com.baeldung.designpatterns.dtopattern.api;
+
+import java.util.List;
+
+public class UserDTO {
+    private String name;
+    private List<String> roles;
+
+    public UserDTO(String name, List<String> roles) {
+        this.name = name;
+        this.roles = roles;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public List<String> getRoles() {
+        return roles;
+    }
+
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/api/UserIdDTO.java

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+package com.baeldung.designpatterns.dtopattern.api;
+
+public class UserIdDTO {
+
+    private String id;
+
+    public UserIdDTO(String id) {
+        this.id = id;
+    }
+
+    public String getId() {
+        return id;
+    }
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/domain/InMemoryRepository.java

@@ -0,0 +1,49 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+import org.springframework.stereotype.Service;
+
+import java.util.*;
+
+@Service
+class InMemoryRepository implements UserRepository, RoleRepository {
+
+    private Map<String, User> users = new LinkedHashMap<>();
+    private Map<String, Role> roles = new LinkedHashMap<>();
+
+    @Override
+    public List<User> getAll() {
+        return new ArrayList<>(users.values());
+    }
+
+    @Override
+    public void save(User user) {
+        user.setId(UUID.randomUUID().toString());
+        users.put(user.getId(), user);
+    }
+
+    @Override
+    public void save(Role role) {
+        role.setId(UUID.randomUUID().toString());
+        roles.put(role.getId(), role);
+    }
+
+    @Override
+    public Role getRoleById(String id) {
+        return roles.get(id);
+    }
+
+    @Override
+    public Role getRoleByName(String name) {
+        return roles.values()
+            .stream()
+            .filter(role -> role.getName().equalsIgnoreCase(name))
+            .findFirst()
+            .orElse(null);
+    }
+
+    @Override
+    public void deleteAll() {
+        users.clear();
+        roles.clear();
+    }
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/domain/Role.java

@@ -0,0 +1,28 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+import java.util.Objects;
+
+public class Role {
+    private String id;
+    private String name;
+
+    public Role(String name) {
+        this.name = Objects.requireNonNull(name);
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    void setId(String id) {
+        this.id = Objects.requireNonNull(id);
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = Objects.requireNonNull(name);
+    }
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/domain/RoleRepository.java

@@ -0,0 +1,7 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+public interface RoleRepository {
+    Role getRoleById(String id);
+    Role getRoleByName(String name);
+    void save(Role role);
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/domain/RoleService.java

@@ -0,0 +1,32 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+import org.springframework.stereotype.Service;
+
+import java.util.Objects;
+
+@Service
+public class RoleService {
+
+    private RoleRepository repository;
+
+    public RoleService(RoleRepository repository) {
+        this.repository = repository;
+    }
+
+    public Role getOrCreate(String name) {
+        Role role = repository.getRoleByName(name);
+
+        if (role == null) {
+            role = new Role(name);
+            repository.save(role);
+        }
+
+        return role;
+    }
+
+    public void save(Role role) {
+        Objects.requireNonNull(role);
+        repository.save(role);
+    }
+
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/domain/User.java

@@ -0,0 +1,80 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+import javax.crypto.*;
+import javax.crypto.spec.SecretKeySpec;
+import java.nio.charset.StandardCharsets;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+
+public class User {
+
+    private static SecretKeySpec KEY = initKey();
+
+    static SecretKeySpec initKey(){
+        try {
+            SecretKey secretKey = KeyGenerator.getInstance("AES").generateKey();
+            return new SecretKeySpec(secretKey.getEncoded(), "AES");
+        } catch (NoSuchAlgorithmException ex) {
+            return null;
+        }
+    }
+
+    private String id;
+    private String name;
+    private String password;
+    private List<Role> roles;
+
+    public User(String name, String password, List<Role> roles) {
+        this.name = Objects.requireNonNull(name);
+        this.password = this.encrypt(password);
+        this.roles = Objects.requireNonNull(roles);
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public void addRole(Role role) {
+        roles.add(role);
+    }
+
+    public List<Role> getRoles() {
+        return Collections.unmodifiableList(roles);
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    void setId(String id) {
+        this.id = id;
+    }
+
+    String encrypt(String password) {
+        Objects.requireNonNull(password);
+        try {
+            Cipher cipher = Cipher.getInstance("AES");
+            cipher.init(Cipher.ENCRYPT_MODE, KEY);
+            final byte[] encryptedBytes = cipher.doFinal(password.getBytes(StandardCharsets.UTF_8));
+            return new String(encryptedBytes, StandardCharsets.UTF_8);
+        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e) {
+            // do nothing
+            return "";
+        }
+    }
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/domain/UserRepository.java

@@ -0,0 +1,9 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+import java.util.List;
+
+public interface UserRepository {
+    List<User> getAll();
+    void save(User user);
+    void deleteAll();
+}

design-patterns/dto-pattern/src/main/java/com/baeldung/designpatterns/dtopattern/domain/UserService.java

@@ -0,0 +1,25 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+import java.util.Objects;
+
+@Service
+public class UserService {
+
+    private UserRepository repository;
+
+    public UserService(UserRepository repository) {
+        this.repository = repository;
+    }
+
+    public List<User> getAll() {
+        return repository.getAll();
+    }
+
+    public void save(User user) {
+        Objects.requireNonNull(user);
+        repository.save(user);
+    }
+}

design-patterns/dto-pattern/src/test/java/com/baeldung/designpatterns/dtopattern/api/MapperUnitTest.java

@@ -0,0 +1,56 @@
+package com.baeldung.designpatterns.dtopattern.api;
+
+import com.baeldung.designpatterns.dtopattern.domain.Role;
+import com.baeldung.designpatterns.dtopattern.domain.User;
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class MapperUnitTest {
+
+    @Test
+    void toDto_shouldMapFromDomainToDTO() {
+        String name = "Test";
+        String password = "test";
+        Role admin = new Role("admin");
+        List<String> expectedRoles = Collections.singletonList("admin");
+
+        List<Role> roles = new ArrayList<>();
+        roles.add(admin);
+
+        User user = new User(name, password, roles);
+        Mapper mapper = new Mapper();
+
+        UserDTO dto = mapper.toDto(user);
+
+        assertEquals(name, dto.getName());
+        assertEquals(expectedRoles, dto.getRoles());
+    }
+
+    @Test
+    void toUser_shouldMapFromDTOToDomain() {
+        String name = "Test";
+        String password = "test";
+        String role = "admin";
+
+        UserCreationDTO dto = new UserCreationDTO();
+        dto.setName(name);
+        dto.setPassword(password);
+        dto.setRoles(Collections.singletonList("admin"));
+
+        User expectedUser = new User(name, password, new ArrayList<>());
+
+        Mapper mapper = new Mapper();
+
+        User user = mapper.toUser(dto);
+
+        assertEquals(name, user.getName());
+        assertEquals(expectedUser.getPassword(), user.getPassword());
+        assertEquals(Collections.emptyList(), user.getRoles());
+    }
+
+}

design-patterns/dto-pattern/src/test/java/com/baeldung/designpatterns/dtopattern/api/UserControllerIntegrationTest.java

@@ -0,0 +1,80 @@
+package com.baeldung.designpatterns.dtopattern.api;
+
+import com.baeldung.designpatterns.dtopattern.domain.Role;
+import com.baeldung.designpatterns.dtopattern.domain.RoleRepository;
+import com.baeldung.designpatterns.dtopattern.domain.User;
+import com.baeldung.designpatterns.dtopattern.domain.UserRepository;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.restassured.http.ContentType;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.web.server.LocalServerPort;
+
+import java.util.Collections;
+
+import static io.restassured.RestAssured.given;
+import static org.hamcrest.CoreMatchers.*;
+import static org.springframework.http.HttpStatus.OK;
+
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+class UserControllerIntegrationTest {
+
+    @Autowired
+    private TestRestTemplate restTemplate;
+
+    @Autowired
+    private UserRepository userRepository;
+
+    @Autowired
+    private RoleRepository roleRepository;
+
+    @LocalServerPort
+    int port;
+
+    @Autowired
+    private ObjectMapper objectMapper;
+
+    @Test
+    void create_shouldReturnUseId() throws Exception {
+        UserCreationDTO request = new UserCreationDTO();
+        request.setName("User 1");
+        request.setPassword("Test@123456");
+        request.setRoles(Collections.singletonList("admin"));
+
+        given()
+            .contentType(ContentType.JSON)
+            .body(objectMapper.writeValueAsString(request))
+        .when()
+            .port(port)
+            .post("/users")
+        .then()
+            .statusCode(OK.value())
+            .body("id", notNullValue());
+    }
+
+    @Test
+    void getAll_shouldReturnUseDTO() {
+
+        userRepository.deleteAll();
+
+        String roleName = "admin";
+        Role admin = new Role(roleName);
+        roleRepository.save(admin);
+
+        String name = "User 1";
+        User user = new User(name, "Test@123456", Collections.singletonList(admin));
+        userRepository.save(user);
+
+        given()
+            .port(port)
+        .when()
+            .get("/users")
+        .then()
+            .statusCode(OK.value())
+            .body("size()", is(1))
+            .body("[0].name", equalTo(name))
+            .body("[0].roles", hasItem(roleName));
+    }
+}

design-patterns/dto-pattern/src/test/java/com/baeldung/designpatterns/dtopattern/domain/InMemoryRepositoryUnitTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+class InMemoryRepositoryUnitTest {
+
+    @Test
+    void getAll_shouldReturnAllUsers() {
+
+        String name = "Test";
+        String password = "test123";
+        List<Role> roles = new ArrayList<>();
+
+        User user = new User(name, password, roles);
+        List<User> expectedUsers = Collections.singletonList(user);
+
+        InMemoryRepository repository = new InMemoryRepository();
+        repository.save(user);
+
+        List<User> users = repository.getAll();
+
+        assertEquals(expectedUsers, users);
+    }
+
+    @Test
+    void save_whenSavingUser_shouldSetId() {
+        String name = "Test";
+        String password = "test123";
+        List<Role> roles = new ArrayList<>();
+
+        User user = new User(name, password, roles);
+
+        InMemoryRepository repository = new InMemoryRepository();
+        repository.save(user);
+
+        assertNotNull(user.getId());
+    }
+
+    @Test
+    void save_whenSavingRole_shouldSetId() {
+        String name = "Test";
+        Role role = new Role(name);
+
+        InMemoryRepository repository = new InMemoryRepository();
+        repository.save(role);
+
+        assertNotNull(role.getId());
+    }
+
+    @Test
+    void getRoleById_shouldReturnRoleById() {
+        String name = "Test";
+        Role expectedRole = new Role(name);
+
+        InMemoryRepository repository = new InMemoryRepository();
+        repository.save(expectedRole);
+
+        Role role = repository.getRoleById(expectedRole.getId());
+
+        assertEquals(expectedRole, role);
+    }
+
+    @Test
+    void getRoleByName_shouldReturnRoleByName() {
+        String name = "Test";
+        Role expectedRole = new Role(name);
+
+        InMemoryRepository repository = new InMemoryRepository();
+        repository.save(expectedRole);
+
+        Role role = repository.getRoleByName(name);
+
+        assertEquals(expectedRole, role);
+    }
+
+}

design-patterns/dto-pattern/src/test/java/com/baeldung/designpatterns/dtopattern/domain/UserUnitTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.designpatterns.dtopattern.domain;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class UserUnitTest {
+
+
+    @Test
+    void whenUserIsCreated_shouldEncryptPassword() {
+        User user = new User("Test", "test", new ArrayList<>());
+
+        assertEquals(user.encrypt("test"), user.getPassword());
+        assertNotEquals(user.encrypt("Test"), user.getPassword());
+    }
+
+    @Test
+    void whenUserIsCreated_shouldFailIfNameIsNull() {
+        assertThrows(NullPointerException.class, () ->
+            new User(null, "test", new ArrayList<>()));
+    }
+
+    @Test
+    void whenUserIsCreated_shouldFailIfPasswordIsNull() {
+        assertThrows(NullPointerException.class, () ->
+            new User("Test", null, new ArrayList<>()));
+    }
+
+    @Test
+    void whenUserIsCreated_shouldFailIfRolesIsNull() {
+        assertThrows(NullPointerException.class, () ->
+            new User("Test", "Test", null));
+    }
+
+}

design-patterns/pom.xml

@@ -0,0 +1,22 @@
+<?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">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.designpatterns</groupId>
+    <artifactId>design-patterns</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+    <name>design-patterns</name>
+    <packaging>pom</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <modules>
+        <module>dto-pattern</module>
+    </modules>
+
+</project>

pom.xml

@@ -387,6 +387,7 @@
                 <module>core-groovy-strings</module>
 
                 <module>core-java-modules</module>
+                <module>design-patterns</module>
 
                 <module>couchbase</module>
                 <module>custom-pmd</module>