前言

Netflix 已開放其 Domain Graph Service（DGS）框架的源代碼 ，該框架是為了方便整合 GraphQL 使用，用于簡化 GraphQL 的實現。

GraphQL 主要是作用于數據接口，比如前端后端交互。無需定義或修改后臺 Controller、Service 等業務代碼即可實現靈活的數據變更，客戶端可以自由獲取服務端事先定義好的數據，提高了交互接口的靈活性

組件依賴

graphql-dgs-spring-boot-starter

<dependency>
    <groupId>com.netflix.graphql.dgs</groupId>
    <artifactId>graphql-dgs-spring-boot-starter</artifactId>
    <version>3.5.1</version>
</dependency>

DGS 必須從 jcenter 下載,不然部分依賴者無法下載。踩坑很久

    <profiles>
        <profile>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <repositories>
                <repository>
                    <snapshots>
                        <enabled>false</enabled>
                    </snapshots>
                    <id>central</id>
                    <name>bintray</name>
                    <url>https://jcenter.bintray.com</url>
                </repository>
            </repositories>
            <pluginRepositories>
                <pluginRepository>
                    <snapshots>
                        <enabled>false</enabled>
                    </snapshots>
                    <id>central</id>
                    <name>bintray-plugins</name>
                    <url>https://jcenter.bintray.com</url>
                </pluginRepository>
            </pluginRepositories>
            <id>bintray</id>
        </profile>
    </profiles>

定義接口 schema

/src/main/resources/schema/schema.graphqls

此文件定義了客戶端請求入參格式和查詢數據類型

type Query {
    shows(title: String ,releaseYear: Int): [Show]
}

type Show {
    title: String
    releaseYear: Int
}

定義數據抽取規則

@DgsComponent
public class ShowsDatafetcher {

    @DgsData(parentType = "Query", field = "shows")
    public List<Show> shows(@InputArgument("title") String title, @InputArgument("releaseYear") Integer releaseYear) {
        if (title == null) {
            return shows;
        }

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

    // 模擬 DB 查詢
    private final List<Show> shows = List.of(
            new Show("JAVA", 1995),
            new Show("php", 1995),
            new Show("Python", 1990),
            new Show("golang", 2009),
            new Show("rust", 2015)
    );
}

UI 前端調試

訪問:
http://localhost:8080/graphiql

條件查詢

接口調用

curl --location --request POST 'http://localhost:8080/graphql' 
--header 'Content-Type: Application/json' 
--data-raw '{"query":"{n  shows(title: "java", releaseYear: 1995) {n    titlen    releaseYearn  }n}n","variables":null}'

java 調用

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

    @Autowired
    DgsQueryExecutor dgsQueryExecutor;

    @Test
    void shows() {
        List<String> titles = dgsQueryExecutor.executeAndExtractJsonPath(
                " { shows { title releaseYear }}",
                "data.shows[*].title");
        assertThat(titles).contains("java");
    }
}