前言

.NETflix 已开放其 DomAIn Graph Service（DGS）框架的源代码 ，该框架是为了方便整合 GraphQL 使用，用于简化 GraphQL 的实现。

GraphQL 主要是作用于数据接口，比如前端后端交互。无需定义或修改后台 Controller、Service 等业务代码即可实现灵活的数据变更，客户端可以自由获取服务端事先定义好的数据，提高了交互接口的灵活性

组件依赖

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 必须从 jcenter 下载,不然部分依赖者无法下载。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>

定义接口 schema

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

此文件定义了客户端请求入参格式和查询数据类型

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

type Show {
    title: String
    releaseYear: Int
}

定义数据抽取规则

@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());
    }

    // 模拟 DB 查询
    private final List<Show> shows = List.of(
            new Show("JAVA", 1995),
            new Show("php", 1995),
            new Show("Python/ target=_blank class=infotextkey>Python", 1990),
            new Show("golang", 2009),
            new Show("Rust", 2015)
    );
}

UI 前端调试

访问:
http://localhost:8080/graphiql

条件查询

接口调用

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 调用

@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");
    }
}