如何真正使用Java构建GraphQL服务器

<dependencyManagement>

    <dependencies>

      ...

        <dependency>

            <groupId>com.netflix.graphql.dgs</groupId>

            <artifactId>graphql-dgs-platform-dependencies</artifactId>

            <version>4.9.16</version>

            <type>pom</type>

            <scope>import</scope>

        </dependency>

      ...

    </dependencies>

</dependencyManagement>



<dependencies>

  ...

    <dependency>

        <groupId>com.netflix.graphql.dgs</groupId>

        <artifactId>graphql-dgs-spring-boot-starter</artifactId>

    </dependency>

  ...

</dependencies>

type Query {

    shows(titleFilter: String): [Show]

    secureNone: String

    secureUser: String

    secureAdmin: String

}



type Mutation {

    addReview(review: SubmittedReview): [Review]

    addReviews(reviews: [SubmittedReview]): [Review]

    addArtwork(showId: Int!, upload: Upload!): [Image]! @skipcodegen

}



type Subscription {

    reviewAdded(showId: Int!): Review

}



type Show {

    id: Int

    title: String @uppercase

    releaseYear: Int

    reviews(minScore:Int): [Review]

    artwork: [Image]

}



type Review {

    username: String

    starScore: Int

    submittedDate: DateTime

}



input SubmittedReview {

    showId: Int!

    username: String!

    starScore: Int!

}



type Image {

    url: String

}



scalar DateTime

scalar Upload

directive @skipcodegen on FIELD_DEFINITION

directive @uppercase on FIELD_DEFINITION

package com.example.demo.datafetchers;



import com.example.demo.generated.types.*;

import com.example.demo.services.*;

import com.netflix.graphql.dgs.*;

import java.util.*;

import java.util.stream.*;

@DgsComponent            // Mark this class as DGS Component

public class ShowsDataFetcher {

    private final ShowsService showsService;



    public ShowsDataFetcher(ShowsService showsService) {

        this.showsService = showsService;

    }



    @DgsQuery            // Mark this class as a DGS DataFetcher

    public List<Show> shows(@InputArgument("titleFilter") String titleFilter) {

        if (titleFilter == null) return showsService.shows();

        return showsService.shows().stream().filter(s -> s.getTitle().contains(titleFilter)).collect(Collectors.toList());

    }

}

public class Show {

    private final UUID id;

    private final String title;

    private final Integer releaseYear;



    public Show(UUID id, String title, Integer releaseYear) {

        this.id = id;

        this.title = title;

        this.releaseYear = releaseYear;

    }



    public UUID getId() {

        return id;

    }



    public String getTitle() {

        return title;

    }



    public Integer getReleaseYear() {

        return releaseYear;

    }

}  

<dependencyManagement>

  <dependencies>

    ...

    <dependency>

      <groupId>org.hibernate.orm</groupId>

      <artifactId>hibernate-platform</artifactId>

      <version>6.4.4.Final</version>

      <type>pom</type>

      <scope>import</scope>

    </dependency>

    ...

  </dependencies>

</dependencyManagement>



<dependencies>

  ...

  <dependency>

    <groupId>org.hibernate.orm</groupId>

    <artifactId>hibernate-core</artifactId>

  </dependency>

  ...

</dependencies>

hibernate.connection.url=<JDBC url>

hibernate.connection.username=<DB role name>

hibernate.connection.password=<DB credential secret>

@Entity                // Mark this as a persistent Entity

@Table(name = "shows")        // Name its table if different

public class Show {

    @Id                // Mark the field as a primary key

    @GeneratedValue        // Specify that the db generates this

    private final UUID id;

    private final String title;

    private final Integer releaseYear;



    public Show(UUID id, String title, Integer releaseYear) {

        this.id = id;

        this.title = title;

        this.releaseYear = releaseYear;

    }



    public UUID getId() {

        return id;

    }



    public String getTitle() {

        return title;

    }



    public Integer getReleaseYear() {

        return releaseYear;

    }

}  

<!DOCTYPE hibernate-mapping PUBLIC

    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <class entity-name="Show">

      <id name="id" column="id" length="32" type="string"/> <!--no native UUID type in Hibernate mapping-->

      <property name="title" not-null="true" length="50" type="string"/>

      <property name="releaseYear" not-null="true" length="50" type="integer"/>

    </class>

</hibernate-mapping>

package com.example.demo.services;



import com.example.demo.generated.types.*;

import java.util.*;

import org.hibernate.cfg.*;

import org.springframework.stereotype.*;

import static org.hibernate.cfg.AvailableSettings.*;



@Service

public class ShowsServiceImpl implements ShowsService {

    private StandardServiceRegistry registry;

    private SessionFactory sessionFactory;



    public ShowsServiceImpl() {

        try {

            this.registry = new StandardServiceRegistryBuilder().build();

            this.sessionFactory = 

                new MetadataSources(this.registry)             

                .addAnnotatedClass(Show.class) // Add every Model class to the Hibernate metadata

                .buildMetadata()                  

                .buildSessionFactory();           

        }

        catch (Exception e) {

            StandardServiceRegistryBuilder.destroy(this.registry);

        }

    }



    @Override

    public List<Show> shows() {

        List<Show> shows = new ArrayList<>();

        sessionFactory.inTransaction(session -> {

                session.createSelectionQuery("from Show", Show.class) // 'Show' is mentioned twice

                    .getResultList()   

                    .forEach(show -> shows.add(show));

            });

        return shows;

    }

}

<dependencies>

  ...

  <dependency>

    <groupId>org.mockito</groupId>

    <artifactId>mockito-inline</artifactId>

    <version>{mockitoversion}</version>

  </dependency>

  <dependency>

    <groupId>org.mockito</groupId>

    <artifactId>mockito-junit-jupiter</artifactId>

    <version>{mockitoversion}</version>

    <scope>test</scope>

  </dependency>

  ...

</dependencies>

import com.netflix.graphql.dgs.*;

import com.netflix.graphql.dgs.autoconfig.*;

import java.util.*;

import org.junit.jupiter.api.*;

import org.mockito.*;

import org.springframework.beans.factory.annotation.*;

import org.springframework.boot.test.context.*;

import static org.assertj.core.api.Assertions.assertThat;



@SpringBootTest(classes = {DgsAutoConfiguration.class, ShowsDataFetcher.class})

public class ShowsDataFetcherTests {

    @Autowired

    DgsQueryExecutor dgsQueryExecutor;



    @MockBean

    ShowsService showsService;



    @BeforeEach

    public void before() {

        Mockito.when(showsService.shows()).thenAnswer(invocation -> List.of(new Show("mock title", 2020)));

    }



    @Test

    public void showsWithQueryApi() {

        GraphQLQueryRequest graphQLQueryRequest = new GraphQLQueryRequest(

                new ShowsGraphQLQuery.Builder().build(),

                new ShowsProjectionRoot().title()

        );

        List<String> titles = dgsQueryExecutor.executeAndExtractJsonPath(graphQLQueryRequest.serialize(), "data.shows[*].title");

        assertThat(titles).containsExactly("mock title");

    }

}