解决什么问题

根据请求控制返回结果

例如： 一个User对象，有id，name，mobile，email

有些接口只要返回id,name ，有些接口还要要返回 mobile

适用场景

• 弱文档管理，公司对文档要求不高
• 需求复杂变化快
• 单资源多种访问方式，组件复用
• 复杂API 还是restful好

开发流程

1.设计领域对象

2.定义GraphQL Schema

3.定义DataFetcher（实现数据访问层组件）

4.完成Data Wiring（GraphQlSourceBuilderCustomizer，旧版本RuntimeWiringBuilderCustomizer）

5.开启graph配置或者自己实现Controller

 spring.graphql.schema.printer.enabled=true

 spring.graphql.path=/wenl/query

GraphQL Server实例

前提

spring boot 2.7+，JDK1.8，maven 3.5+

maven pom如下：

	<parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.13-SNAPSHOT</version><relativePath/> <!-- lookup parent from repository --></parent><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-graphql</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webflux</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.graphql</groupId><artifactId>spring-graphql-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>3.1.0</version></plugin></plugins></build>

设计领域对象

@Data
public class Author {private Long id;private String firstName;private String lastName;
}

@Data
@NoArgsConstructor
public class Book {private String id;private String name;private int pageCount;private Author author;public static List<Book> books = Arrays.asList(new Book("book-1", "Effective Java", 416, "author-1"),new Book("book-2", "Hitchhiker's Guide to the Galaxy", 208, "author-2"),new Book("book-3", "Down Under", 436, "author-3"));public Book(String id, String name, int pageCount, String authorName) {this.id = id;this.name = name;this.pageCount = pageCount;Author author = new Author();author.setFirstName(authorName);author.setLastName("lastName");this.author=author;}
}

定义GraphQL Schema

文件位置固定文件名固定，resources/graphql/schema.graphqls

schema {query : Query
}type Query {books: [Book]bookById(id: String,name: String ): Book
}type Book {id: IDname: StringpageCount: Intauthor: Author
}type Author {id: IDfirstName: StringlastName: String
}

schema 是固定写法

type Query  内部是对应的查询方法。

books: [Book] 表示方法名称为books（client需要配置） ，返回的是list

bookById(id: String,name: String ): Book   这里返回单个Book，id，name是参数

其他的type 是返回值的类。

定义DataFetcher（实现数据访问层组件）

@Component
public class BookDataFetcher implements DataFetcher<Book> {@Overridepublic Book get(DataFetchingEnvironment dataFetchingEnvironment) throws Exception {String id = (String) dataFetchingEnvironment.getArguments().get("id");String name = (String) dataFetchingEnvironment.getArguments().get("name");return Book.books.stream().filter(book -> book.getId().equals(id)&&book.getName().equals(name)).findFirst().orElse(null);}}

@Component
public class BooksDataFetcher implements DataFetcher<List<Book>> {@Overridepublic List<Book> get(DataFetchingEnvironment dataFetchingEnvironment) throws Exception {return Book.books;}}

完成Data Wiring（GraphQlSourceBuilderCustomizer，旧版本RuntimeWiringBuilderCustomizer）

@Component
public class CustomerStaffDataWiring implements GraphQlSourceBuilderCustomizer {@Autowiredprivate BooksDataFetcher booksDataFetcher;@Autowiredprivate BookDataFetcher bookDataFetcher;@Overridepublic void customize(GraphQlSource.SchemaResourceBuilder builder) {builder.configureRuntimeWiring(new RuntimeWiringConfigurer() {@Overridepublic void configure(RuntimeWiring.Builder builder) {builder.type("Query", typeWiring -> typeWiring.dataFetcher("books", booksDataFetcher).dataFetcher("bookById",bookDataFetcher));}});}
}

开启graph配置或者自己实现Controller

 spring.graphql.schema.printer.enabled=true

 spring.graphql.path=/wenl/query

自实现Controller

@RestController
public class BookController {private GraphQL graphQL;@Autowiredpublic BookController(GraphQlSource graphQlSource) {graphQL = graphQlSource.graphQl();}@Datapublic static class GraphQLInput{String query;Map<String,Object> variables;}@PostMapping(value = "/wenl/query")public ResponseEntity<Object> query(@RequestBody GraphQLInput graphQLInput) {ExecutionInput.Builder executionInputBuilder = new ExecutionInput.Builder();executionInputBuilder.query(graphQLInput.getQuery());executionInputBuilder.variables(graphQLInput.getVariables());ExecutionResult result = graphQL.execute(executionInputBuilder);return ResponseEntity.ok(result.getData());}
}

GraphQL Client 调用方式

就是简单的POST 调用json方式，下面就使用Apifox 说明

返回值如下：

调用JSON说明

{
    "query":"query books($id:String,$name:String){ bookById(id:$id,name:$name){ id name pageCount author { firstName  }}}",
    "variables":{
        "id":"book-1",
        "name":"Effective Java"
    }
}

$id,$name 表示参数

query，variables与GraphQLInput 字段一一对应。