spring boot 使用GraphQL

在此之前需要简单了解GraphQL的基本知识，可通过以下来源进行学习

GraphQL官方中文网站 ：https://graphql.cn

GraphQL-java 官网： https://www.graphql-java.com

使用GraphQL需要

　　定义对象模型

　　定义查询类型

　　定义查询操作 schema

#对应的User定义如下
schema {    #定义查询
    query: UserQuery
}
type UserQuery {    #定义查询类型
    user(): User    #指定对象以及参数类型
}
type User { #定义对象
    id: Long!   #!表示非空
    name:String
    age:Int
}

java使用GraphQL需要引入GraphQL-java的依赖

        <!-- The dependence of graphql-java -->
        <dependency>
            <groupId>com.graphql-java</groupId>
            <artifactId>graphql-java</artifactId>
            <version>11.0</version>
        </dependency>

对应的User

public class User {
    private int age;
    private long id;
    private String name;

    public User(int age, long id, String name) {
        this.age = age;
        this.id = id;
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

操作静态数据

import clc.bean.User;
import graphql.ExecutionResult;
import graphql.GraphQL;
import graphql.Scalars;
import graphql.schema.GraphQLFieldDefinition;
import graphql.schema.GraphQLObjectType;
import graphql.schema.GraphQLSchema;
import graphql.schema.StaticDataFetcher;

/**
 * ClassName: GraphQLDemo<br/>
 * Description: <br/>
 * date: 2019/6/28 10:40 AM<br/>
 *
 * @author chengluchao
 * @since JDK 1.8
 */

public class GraphQLDemo {
    public static void main(String[] args) {
        //定义对象
        GraphQLObjectType userObjectType = GraphQLObjectType.newObject()
                .name("User")
                .field(GraphQLFieldDefinition.newFieldDefinition().name("id").type(Scalars.GraphQLLong))
                .field(GraphQLFieldDefinition.newFieldDefinition().name("age").type(Scalars.GraphQLInt))
                .field(GraphQLFieldDefinition.newFieldDefinition().name("name").type(Scalars.GraphQLString))
                .build();
        //user : User 指定对象及参数类型
        GraphQLFieldDefinition userFileldDefinition = GraphQLFieldDefinition.newFieldDefinition()
                .name("user")
                .type(userObjectType)
                //静态数据
                .dataFetcher(new StaticDataFetcher(new User(25, 2, "CLC")))
                .build();
        //type UserQuery 定义查询类型
        GraphQLObjectType userQueryObjectType = GraphQLObjectType.newObject()
                .name("UserQuery")
                .field(userFileldDefinition)
                .build();
        //Schema 定义查询
        GraphQLSchema qlSchema = GraphQLSchema.newSchema().query(userQueryObjectType).build();

        GraphQL graphQL = GraphQL.newGraphQL(qlSchema).build();
        String query = "{user{id,name,age}}";
        ExecutionResult result = graphQL.execute(query);
        System.out.println(result.toSpecification());
    }
}

操作动态数据，数据源可以是数据库，缓存或者是其他服务，

此例通过动态传递id获取user数据，模拟实现动态数据

import clc.bean.User;
import graphql.ExecutionResult;
import graphql.GraphQL;
import graphql.Scalars;
import graphql.schema.GraphQLArgument;
import graphql.schema.GraphQLFieldDefinition;
import graphql.schema.GraphQLObjectType;
import graphql.schema.GraphQLSchema;

/**
 * ClassName: GraphQLDemo<br/>
 * Description: <br/>
 * date: 2019/6/28 10:40 AM<br/>
 *
 * @author chengluchao
 * @since JDK 1.8
 */

public class GraphQLDemo2 {
    public static void main(String[] args) {
        //定义对象
        GraphQLObjectType userObjectType = GraphQLObjectType.newObject()
                .name("User")
                .field(GraphQLFieldDefinition.newFieldDefinition().name("id").type(Scalars.GraphQLLong))
                .field(GraphQLFieldDefinition.newFieldDefinition().name("age").type(Scalars.GraphQLInt))
                .field(GraphQLFieldDefinition.newFieldDefinition().name("name").type(Scalars.GraphQLString))
                .build();
        //user : User 指定对象及参数类型
        GraphQLFieldDefinition userFileldDefinition = GraphQLFieldDefinition.newFieldDefinition()
                .name("user")
                .type(userObjectType)
                .argument(GraphQLArgument.newArgument().name("id").type(Scalars.GraphQLLong).build())
                //动态数据
                .dataFetcher(environment -> {
                    Long id = environment.getArgument("id");
                    //查库或者调用其他服务
                    return new User(20, id, "模拟用户1");
                })
                .build();
        //type UserQuery 定义查询类型
        GraphQLObjectType userQueryObjectType = GraphQLObjectType.newObject()
                .name("UserQuery")
                .field(userFileldDefinition)
                .build();
        //Schema 定义查询
        GraphQLSchema qlSchema = GraphQLSchema.newSchema().query(userQueryObjectType).build();

        GraphQL graphQL = GraphQL.newGraphQL(qlSchema).build();
        String query = "{user(id:15){id,name,age}}";
        ExecutionResult result = graphQL.execute(query);
        System.out.println(result.toSpecification());
    }
}

以上两个例子都是通过GraphQLObjectType的field等方法来定义模型，除此之外还可以通过SDL文件来生成模型

在resource目录下创建user.graphqls文件

#对应的User定义如下
schema {    #定义查询
    query: UserQuery
}
type UserQuery {    #定义查询类型
    user(id:Long) : User    #指定对象以及参数类型
}
type User { #定义对象
    id: Long!   #!表示非空
    name:String
    age:Int
}

然后程序读取此文件即可解析成模型；

在此之前需要添加一个依赖包用于读取文件

     <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>

详情如下：

　　

import clc.bean.User;
import graphql.ExecutionResult;
import graphql.GraphQL;
import graphql.schema.GraphQLSchema;
import graphql.schema.idl.RuntimeWiring;
import graphql.schema.idl.SchemaGenerator;
import graphql.schema.idl.SchemaParser;
import graphql.schema.idl.TypeDefinitionRegistry;
import org.apache.commons.io.IOUtils;


/**
 * ClassName: GraphQLSDLDemo<br/>
 * Description: <br/>
 * date: 2019/6/28 11:19 AM<br/>
 *
 * @author chengluchao
 * @since JDK 1.8
 */

public class GraphQLSDLDemo {
    public static void main(String[] args) throws Exception {
        //读取graphqls文件
        String fileName = "user.graphqls";
        String fileContent = IOUtils.toString(GraphQLSDLDemo.class.getClassLoader().getResource(fileName), "UTF-8");
        //解析文件
        TypeDefinitionRegistry typeDefinitionRegistry = new SchemaParser().parse(fileContent);

        RuntimeWiring wiring = RuntimeWiring.newRuntimeWiring()
                .type("UserQuery", builder ->
                        builder.dataFetcher("user", environment -> {
                            Long id = environment.getArgument("id");
                            return new User(18, id, "user0" + id);
                        })
                )
                .build();

        GraphQLSchema graphQLSchema = new SchemaGenerator().makeExecutableSchema(typeDefinitionRegistry, wiring);

        GraphQL graphQL = GraphQL.newGraphQL(graphQLSchema).build();

        String query = "{user(id:15){id,name,age}}";
        ExecutionResult result = graphQL.execute(query);

        System.out.println("query: " + query);
        System.out.println(result.toSpecification());
    }
}

官方推荐第二种方式

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原文地址：https://www.cnblogs.com/chenglc/p/11103269.html