comments, tests and description

api-gateway/api-gateway-service/src/main/java/com/iluwatar/api/gateway/ImageClientImpl.java

@@ -35,7 +35,7 @@ import java.io.IOException;
  * An adapter to communicate with the Image microservice
  */
 @Component
-public class ImageClientImpl implements ImageClient{
+public class ImageClientImpl implements ImageClient {
   /**
    * Makes a simple HTTP Get request to the Image microservice
    * @return The path to the image

api-gateway/api-gateway-service/src/main/java/com/iluwatar/api/gateway/PriceClientImpl.java

@@ -35,7 +35,7 @@ import java.io.IOException;
  * An adapter to communicate with the Price microservice
  */
 @Component
-public class PriceClientImpl implements PriceClient{
+public class PriceClientImpl implements PriceClient {
   /**
    * Makes a simple HTTP Get request to the Price microservice
    * @return The price of the product

converter/README.md

@@ -10,16 +10,20 @@ tags:
 ---
 
 ## Intent
-TODO
+The purpose of the Converter Pattern is to provide a generic, common way of bidirectional
+conversion between corresponding types, allowing a clean implementation in which the types do not
+need to be aware of each other. Moreover, the Converter Pattern introduces bidirectional collection
+mapping, reducing a boilerplate code to minimum.
 
-![alt text](./etc/converter.png "TODO")
+![alt text](./etc/converter.png "Converter Pattern")
 
 ## Applicability
-TODO
+Use the Converter Pattern in the following situations:
 
-* TODO 1
-* TODO 2
+* When you have types that logically correspond which other and you need to convert entities between them
+* When you want to provide different ways of types conversions depending on a context
+* Whenever you introduce a DTO (Data transfer object), you will probably need to convert it into the domain equivalence
 
 ## Credits
 
-* [Converter](http://todo.com)
+* [Converter](http://www.xsolve.pl/blog/converter-pattern-in-java-8/)

converter/pom.xml

@@ -14,6 +14,10 @@
             <artifactId>junit</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+        </dependency>
     </dependencies>
     <artifactId>converter</artifactId>
 

converter/src/main/java/com/iluwatar/converter/App.java

@@ -22,6 +22,18 @@
  */
 package com.iluwatar.converter;
 
+
+import com.google.common.collect.Lists;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * The Converter pattern is a behavioral design pattern which allows a common way of bidirectional
+ * conversion between corresponding types (e.g. DTO and domain representations of the logically
+ * isomorphic types). Moreover, the pattern introduces a common way of converting a collection of
+ * objects between types.
+ */
 public class App {
   /**
    * Program entry point
@@ -30,11 +42,22 @@ public class App {
    */
   public static void main(String[] args) {
     Converter<UserDto, User> userConverter = new Converter<>(
-        userDto -> new User(userDto.getFirstName(), userDto.getLastName(), userDto.isActive()),
-        user -> new UserDto(user.getFirstName(), user.getLastName(), user.isActive()));
-    UserDto dtoUser = new UserDto("John", "Doe", true);
+        userDto -> new User(userDto.getFirstName(), userDto.getLastName(), userDto.isActive(),
+          userDto.getEmail()),
+        user -> new UserDto(user.getFirstName(), user.getLastName(), user.isActive(), user.getUserId()));
+
+    UserDto dtoUser = new UserDto("John", "Doe", true, "whatever[at]wherever.com");
     User user = userConverter.convertFromDto(dtoUser);
     UserDto dtoUserCopy = userConverter.convertFromEntity(user);
 
+    ArrayList<User> users = Lists.newArrayList(new User("Camile", "Tough", false, "124sad"),
+        new User("Marti", "Luther", true, "42309fd"), new User("Kate", "Smith", true, "if0243"));
+    System.out.println("Domain entities:");
+    users.forEach(System.out::println);
+
+    System.out.println("DTO entities converted from domain:");
+    List<UserDto> dtoEntities = userConverter.createFromEntities(users);
+    dtoEntities.forEach(System.out::println);
+
   }
 }

converter/src/main/java/com/iluwatar/converter/Converter.java

@@ -29,6 +29,9 @@ import java.util.function.Function;
 import java.util.stream.Collectors;
 
 /**
+ * Generic converter, thanks to Java8 features not only provides a way of generic bidirectional
+ * conversion between coresponding types, but also a common way of converting a collection of objects
+ * of the same type, reducing boilerplate code to the absolute minimum.
  * @param <T> DTO representation's type
  * @param <U> Domain representation's type
  */
@@ -47,37 +50,37 @@ public class Converter<T, U> {
   }
 
   /**
-   * @param arg DTO entity
+   * @param userDto DTO entity
    * @return The domain representation - the result of the converting function application on dto entity.
    */
-  public U convertFromDto(final T arg) {
-    return fromDto.apply(arg);
+  public final U convertFromDto(final T userDto) {
+    return fromDto.apply(userDto);
   }
 
   /**
-   * @param arg domain entity
+   * @param user domain entity
    * @return The DTO representation - the result of the converting function application on domain entity.
    */
-  public T convertFromEntity(final U arg) {
-    return fromEntity.apply(arg);
+  public final T convertFromEntity(final U user) {
+    return fromEntity.apply(user);
   }
 
   /**
-   * @param arg collection of DTO entities
+   * @param dtoUsers collection of DTO entities
    * @return List of domain representation of provided entities retrieved by
    *        mapping each of them with the convertion function
    */
-  public List<U> createFromDtos(final Collection<T> arg) {
-    return arg.stream().map(this::convertFromDto).collect(Collectors.toList());
+  public final List<U> createFromDtos(final Collection<T> dtoUsers) {
+    return dtoUsers.stream().map(this::convertFromDto).collect(Collectors.toList());
   }
 
   /**
-   * @param arg collection of domain entities
+   * @param users collection of domain entities
    * @return List of domain representation of provided entities retrieved by
    *        mapping each of them with the convertion function
    */
-  public List<T> createFromEntities(final Collection<U> arg) {
-    return arg.stream().map(this::convertFromEntity).collect(Collectors.toList());
+  public final List<T> createFromEntities(final Collection<U> users) {
+    return users.stream().map(this::convertFromEntity).collect(Collectors.toList());
   }
 
 }

converter/src/main/java/com/iluwatar/converter/User.java

@@ -23,44 +23,61 @@
 
 package com.iluwatar.converter;
 
+import java.util.Objects;
+
 public class User {
   private String firstName;
   private String lastName;
   private boolean isActive;
+  private String userId;
 
   /**
-   *
    * @param firstName user's first name
-   * @param lastName user's last name
-   * @param isActive flag indicating whether the user is active
+   * @param lastName  user's last name
+   * @param isActive  flag indicating whether the user is active
+   * @param userId user's identificator
    */
-  public User(String firstName, String lastName, boolean isActive) {
+  public User(String firstName, String lastName, boolean isActive, String userId) {
     this.firstName = firstName;
     this.lastName = lastName;
     this.isActive = isActive;
+    this.userId = userId;
   }
 
   public String getFirstName() {
     return firstName;
   }
 
-  public void setFirstName(String firstName) {
-    this.firstName = firstName;
-  }
-
   public String getLastName() {
     return lastName;
   }
 
-  public void setLastName(String lastName) {
-    this.lastName = lastName;
-  }
-
   public boolean isActive() {
     return isActive;
   }
 
-  public void setActive(boolean active) {
-    isActive = active;
+  public String getUserId() {
+    return userId;
+  }
+
+  @Override public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    User user = (User) o;
+    return isActive == user.isActive && Objects.equals(firstName, user.firstName) && Objects
+      .equals(lastName, user.lastName) && Objects.equals(userId, user.userId);
+  }
+
+  @Override public int hashCode() {
+    return Objects.hash(firstName, lastName, isActive, userId);
+  }
+
+  @Override public String toString() {
+    return "User{" + "firstName='" + firstName + '\'' + ", lastName='" + lastName + '\''
+      + ", isActive=" + isActive + ", userId='" + userId + '\'' + '}';
   }
 }

converter/src/main/java/com/iluwatar/converter/UserConverter.java

@@ -0,0 +1,40 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 Ilkka Seppälä
+ * <p>
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.converter;
+
+/**
+ * Example implementation of the simple User converter.
+ */
+public class UserConverter extends Converter<UserDto, User> {
+
+  /**
+   * Constructor.
+   */
+  public UserConverter() {
+    super(userDto -> new User(userDto.getFirstName(), userDto.getLastName(), userDto.isActive(),
+        userDto.getEmail()),
+        user -> new UserDto(user.getFirstName(), user.getLastName(), user.isActive(),
+        user.getUserId()));
+  }
+}

converter/src/main/java/com/iluwatar/converter/UserDto.java

@@ -24,44 +24,62 @@
 package com.iluwatar.converter;
 
 
+import java.util.Objects;
+
 public class UserDto {
+
   private String firstName;
   private String lastName;
   private boolean isActive;
+  private String email;
 
   /**
-   *
    * @param firstName user's first name
-   * @param lastName user's last name
-   * @param isActive flag indicating whether the user is active
+   * @param lastName  user's last name
+   * @param isActive  flag indicating whether the user is active
+   * @param email     user's email address
    */
-  public UserDto(String firstName, String lastName, boolean isActive) {
+  public UserDto(String firstName, String lastName, boolean isActive, String email) {
     this.firstName = firstName;
     this.lastName = lastName;
     this.isActive = isActive;
+    this.email = email;
   }
 
   public String getFirstName() {
     return firstName;
   }
 
-  public void setFirstName(String firstName) {
-    this.firstName = firstName;
-  }
-
   public String getLastName() {
     return lastName;
   }
 
-  public void setLastName(String lastName) {
-    this.lastName = lastName;
-  }
-
   public boolean isActive() {
     return isActive;
   }
 
-  public void setActive(boolean active) {
-    isActive = active;
+  public String getEmail() {
+    return email;
+  }
+
+  @Override public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    UserDto userDto = (UserDto) o;
+    return isActive == userDto.isActive && Objects.equals(firstName, userDto.firstName) && Objects
+      .equals(lastName, userDto.lastName) && Objects.equals(email, userDto.email);
+  }
+
+  @Override public int hashCode() {
+    return Objects.hash(firstName, lastName, isActive, email);
+  }
+
+  @Override public String toString() {
+    return "UserDto{" + "firstName='" + firstName + '\'' + ", lastName='" + lastName + '\''
+      + ", isActive=" + isActive + ", email='" + email + '\'' + '}';
   }
 }

converter/src/test/java/com/iluwatar/converter/ConverterTest.java

@@ -0,0 +1,59 @@
+package com.iluwatar.converter;
+
+import com.google.common.collect.Lists;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class ConverterTest {
+
+  private UserConverter userConverter = new UserConverter();
+
+  /**
+   * Tests whether a converter created of opposite functions holds equality as a bijection.
+   */
+  @Test public void testConversionsStartingFromDomain() {
+    User u1 = new User("Tom", "Hanks", true, "tom@hanks.com");
+    User u2 = userConverter.convertFromDto(userConverter.convertFromEntity(u1));
+    assertEquals(u1, u2);
+  }
+
+  /**
+   * Tests whether a converter created of opposite functions holds equality as a bijection.
+   */
+  @Test public void testConversionsStartingFromDto() {
+    UserDto u1 = new UserDto("Tom", "Hanks", true, "tom@hanks.com");
+    UserDto u2 = userConverter.convertFromEntity(userConverter.convertFromDto(u1));
+    assertEquals(u1, u2);
+  }
+
+  /**
+   * Tests the custom users converter. Thanks to Java8 lambdas, converter can be easily and
+   * cleanly instantiated allowing various different conversion strategies to be implemented.
+   */
+  @Test public void testCustomConverter() {
+    Converter<UserDto, User> converter = new Converter<>(
+      userDto -> new User(userDto.getFirstName(), userDto.getLastName(), userDto.isActive(),
+        String.valueOf(new Random().nextInt())),
+      user -> new UserDto(user.getFirstName(), user.getLastName(), user.isActive(),
+        user.getFirstName().toLowerCase() + user.getLastName().toLowerCase() + "@whatever.com"));
+    User u1 = new User("John", "Doe", false, "12324");
+    UserDto userDto = converter.convertFromEntity(u1);
+    assertEquals(userDto.getEmail(), "johndoe@whatever.com");
+  }
+
+  /**
+   * Test whether converting a collection of Users to DTO Users and then converting them back to domain
+   * users returns an equal collection.
+   */
+  @Test public void testCollectionConversion() {
+    ArrayList<User> users = Lists.newArrayList(new User("Camile", "Tough", false, "124sad"),
+      new User("Marti", "Luther", true, "42309fd"), new User("Kate", "Smith", true, "if0243"));
+    List<User> fromDtos = userConverter.createFromDtos(userConverter.createFromEntities(users));
+    assertEquals(fromDtos, users);
+  }
+}