如何从 Java Spring Boot 应用程序调用 GraphQL API？是否有支持 GraphQL 查询形成的注释？

Question

我正在寻找一种解决方案来从 spring-boot 应用程序实现 GraphQL api 调用，查询架构如下：

query {
    getDetailsByRefNumber(RefNumbers: "")
    {
        field1,
        field2,
        field3 
    } 
}

有谁知道如何实现这个？通过以下链接之一，但没有找到任何解决方案

是否有任何基于 Java 的 Graphql 客户端可以从 java 代码调用 graphql 服务器？

Answer 1

您可以使用“graphql-webclient-spring-boot-starter”库，该库位于：

https://github.com/graphql-java-kickstart/graphql-spring-webclient

<!-- https://mvnrepository.com/artifact/com.graphql-java-kickstart/graphql-webclient-spring-boot-starter -->
<dependency>
  <groupId>com.graphql-java-kickstart</groupId>
  <artifactId>graphql-webclient-spring-boot-starter</artifactId>
  <version>1.0.0</version>
</dependency>

示例实现可以是这样的：

假设您有 MyEntity 对象：

public class MyEntity
{
    String field1;
    String field2;
    String field3;
    //getter and setters here
}

另外，“src/main/resources”文件夹下有两个 graphql 查询文件：

查询1.graphql：

#query1.graphql
#this query returns a list of some_detail_entity
query getDetailListByRefNumber($RefNumber: String!){
    some_detail_entity(where: {RefNumber : { _eq: $RefNumber } }) {
        field1
        field2
        field3 
    } 
}

查询2.graphql：

#query2.graphql
#this query returns a single some_detail_entity
query getDetailByRefNumber($RefNumber: String!){
    some_detail_entity_by_pk(RefNumber : $RefNumber) {
        field1
        field2
        field3 
    } 
}

您可以使用此代码片段调用 graphql 服务器来查询和获取一些数据：

ObjectMapper objectMapper = new ObjectMapper();

WebClient webClient = WebClient.builder()
.baseUrl("https://endpoint-url-of-graphql.com")//url of graphql instance
.defaultHeader("auth-token", "some-cryptic-code-if-required")//if auth header not required, just delete this line
.build();

GraphQLWebClient graphqlClient = GraphQLWebClient.newInstance(webClient, objectMapper);

//if expecting a single entity (not array)
MyObject entity = graphqlClient.post("query2.graphql", 
Map.of("RefNumber", "A7EED900-9BB4-486F-9F7C-2136E61E2278"), MyEntity.class)
            .block();   

            
//if expecting a list of entity (array)
var response = graphqlClient.post(GraphQLRequest.builder().resource("query1.graphql")
        .variables(Map.of("RefNumber", "A7EED900-9BB4-486F-9F7C-2136E61E2278")).build())
                .block();   

List<MyEntity> entityList = response.getFirstList(MyEntity.class);