GraphQL是一个用于API的查询语言，通过GraphQL可以实现按需获取数据。最近Spring发布了Spring GraphQL项目，将GraphQL和Spring结合在一起，可以通过Spring Boot的方式使用GraphQL

引入依赖

    <dependencies>
        <dependency>
            <groupId>org.springframework.experimental</groupId>
            <artifactId>graphql-spring-boot-starter</artifactId>
            <version>1.0.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
    </dependencies>

    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </repository>
        <repository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
    </repositories>

编写yml配置文件

编写spring boot项目的配置文件，在配置文件中指定schema文件的位置

server:
  port: 8888
spring:
  graphql:
    schema:
      printer:
        enabled: true
    locations: /graphql  # 指定schema文件的位置， 默认在resources下的graphql文件夹下

编写schema

schema: 定义数据结构、类型和关系，在schema中定义的type和Java中的实体相对应

type: 对应Java中的实体对象

type Query: 定义查询，在查询时需要按照Query中的定义进行查询，不用映射成java对象，系统中必须存在

在resources/graphql目录下创建schema.graphqls文件，并写入如下内容：

# 定义查询
type Query {
    greeting: String
    author(id: ID!): Author
}

# 定义Author，和java中Author对象对应
type Author {
    id: ID!
    name: String!
    sex: SexEnum
    books: [Book]
}

# 定义Book，和java中Book对象对应
type Book {
    bookName: String!
    publish: Boolean!
    price: Float
}

# 定义枚举，和java中SexEnum对应
enum SexEnum {
    man,
    woman
}

编写实体类

实体类和schema中type定义的属性一致

@Data
public class Author {

    private Integer id;

    private String name;

    private SexEnum sex;

    private List<Book> books;
}


@Data
public class Book {

    private String bookName;

    private boolean publish;

    private float price;
}

public enum SexEnum {

    man, woman;
}

编写查询

@Component
public class CustomizeRuntimeWiring implements RuntimeWiringBuilderCustomizer {

    @Override
    public void customize(RuntimeWiring.Builder builder) {
        
        builder.type("Query", typeWiring -> {
            
            // 查询greeting,返回hello
            typeWiring.dataFetcher("greeting", env -> "hello");

            // 查询作者 
            typeWiring.dataFetcher("author", env -> {

                Integer id = Integer.valueOf(env.getArgument("id"));

                Author author = new Author();
                author.setId(id);
                author.setName("小明");
                author.setSex(SexEnum.man);

                Book book1 = new Book();
                book1.setBookName("无敌拳法十三式");
                book1.setPublish(false);
                book1.setPrice(new SecureRandom().nextFloat());

                Book book2 = new Book();
                book2.setBookName("独孤十三剑");
                book2.setPublish(true);
                book2.setPrice(new SecureRandom().nextFloat());

                author.setBooks(Arrays.asList(book1, book2));

                return author;
            });

            return typeWiring;
        });
    }
}

启动项目查询

项目启动后访问 http://localhost:8888/graphiql 进入查询页面

查询

查询greeting

查询作者信息

查询作者和书籍

CSDN