BAEL-3091: The Prototype Pattern in Java (changed code based on valid comments from a reader)

feign/src/main/java/com/baeldung/feign/BookControllerFeignClientBuilder.java

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+package com.baeldung.feign;
+
+import com.baeldung.feign.clients.BookClient;
+import feign.Feign;
+import feign.Logger;
+import feign.gson.GsonDecoder;
+import feign.gson.GsonEncoder;
+import feign.okhttp.OkHttpClient;
+import feign.slf4j.Slf4jLogger;
+import lombok.Getter;
+
+@Getter
+public class BookControllerFeignClientBuilder {
+    private BookClient bookClient = createClient(BookClient.class, "http://localhost:8081/api/books");
+
+    private static <T> T createClient(Class<T> type, String uri) {
+        return Feign.builder()
+            .client(new OkHttpClient())
+            .encoder(new GsonEncoder())
+            .decoder(new GsonDecoder())
+            .logger(new Slf4jLogger(type))
+            .logLevel(Logger.Level.FULL)
+            .target(type, uri);
+    }
+}

feign/src/main/java/com/baeldung/feign/clients/BookClient.java

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+package com.baeldung.feign.clients;
+
+import com.baeldung.feign.models.Book;
+import com.baeldung.feign.models.BookResource;
+import feign.Headers;
+import feign.Param;
+import feign.RequestLine;
+
+import java.util.List;
+
+public interface BookClient {
+    @RequestLine("GET /{isbn}")
+    BookResource findByIsbn(@Param("isbn") String isbn);
+
+    @RequestLine("GET")
+    List<BookResource> findAll();
+
+    @RequestLine("POST")
+    @Headers("Content-Type: application/json")
+    void create(Book book);
+}

feign/src/main/java/com/baeldung/feign/models/Book.java

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+package com.baeldung.feign.models;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import lombok.ToString;
+
+@Data
+@ToString
+@NoArgsConstructor
+@AllArgsConstructor
+public class Book {
+    private String isbn;
+    private String author;
+    private String title;
+    private String synopsis;
+    private String language;
+}

feign/src/main/java/com/baeldung/feign/models/BookResource.java

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+package com.baeldung.feign.models;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import lombok.ToString;
+
+@Data
+@ToString
+@NoArgsConstructor
+@AllArgsConstructor
+public class BookResource {
+    private Book book;
+}

feign/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

feign/src/test/java/com/baeldung/feign/clients/BookClientLiveTest.java

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+package com.baeldung.feign.clients;
+
+import com.baeldung.feign.BookControllerFeignClientBuilder;
+import com.baeldung.feign.models.Book;
+import com.baeldung.feign.models.BookResource;
+import lombok.extern.slf4j.Slf4j;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+import java.util.List;
+import java.util.UUID;
+import java.util.stream.Collectors;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Consumes https://github.com/Baeldung/spring-hypermedia-api
+ */
+@Slf4j
+@RunWith(JUnit4.class)
+public class BookClientLiveTest {
+    private BookClient bookClient;
+
+    @Before
+    public void setup() {
+        BookControllerFeignClientBuilder feignClientBuilder = new BookControllerFeignClientBuilder();
+        bookClient = feignClientBuilder.getBookClient();
+    }
+
+    @Test
+    public void givenBookClient_shouldRunSuccessfully() throws Exception {
+        List<Book> books = bookClient.findAll()
+            .stream()
+            .map(BookResource::getBook)
+            .collect(Collectors.toList());
+        assertTrue(books.size() > 2);
+        log.info("{}", books);
+    }
+
+    @Test
+    public void givenBookClient_shouldFindOneBook() throws Exception {
+        Book book = bookClient.findByIsbn("0151072558")
+            .getBook();
+        assertThat(book.getAuthor(), containsString("Orwell"));
+        log.info("{}", book);
+    }
+
+    @Test
+    public void givenBookClient_shouldPostBook() throws Exception {
+        String isbn = UUID.randomUUID()
+            .toString();
+        Book book = new Book(isbn, "Me", "It's me!", null, null);
+        bookClient.create(book);
+
+        book = bookClient.findByIsbn(isbn)
+            .getBook();
+        assertThat(book.getAuthor(), is("Me"));
+        log.info("{}", book);
+    }
+}