Java 操作GraphQL Java 通过API操作GraphQL（java模拟器）

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<dependency>
    <groupId>com.graphql-java</groupId>
    <artifactId>graphql-java</artifactId>
    <version>11.0</version>
</dependency>

/**
 * 简单展示 GraphQL的查询，以及通过JavaAPI响应数据
 */
public class GraphQLSimpleDemo {


    public static void main(String[] args) {
        // 定义数据响应对象
        GraphQLObjectType userType = createGraphQLObjectType();
        // 根据定义的数据响应对象构建响应的数据
        GraphQLFieldDefinition userDefinition = createGraphQLFieldDefinition(userType);
        // 创建查询响应
        GraphQLSchema graphQLSchema = createGraphQLSchema(userDefinition);
        GraphQL graphQL = GraphQL.newGraphQL(graphQLSchema).build();

        // 查询语句
        String graph1 = "{User{id, name}}";
        // 查询多个字段
        String graph2 = "{User{id, name, age}}";

        // 执行查询
        ExecutionResult execute = graphQL.execute(graph1);
        // 获取结果
        System.out.println(execute.toSpecification());

        // 执行查询
        ExecutionResult execute2 = graphQL.execute(graph2);
        // 获取结果
        System.out.println(execute2.toSpecification());
    }

    // 创建GraphQLSchema
    public static GraphQLSchema createGraphQLSchema(GraphQLFieldDefinition userDefinition) {
        GraphQLObjectType userQuery = GraphQLObjectType.newObject()
                                                               .name("userQuery")
                                                               .field(userDefinition)
                                                               .build();
        return GraphQLSchema.newSchema().query(userQuery).build();
    }

    /**
     * 创建GraphQLFieldDefinition对象
     *
     * 根据定义的查询对象做真正的查询，返回查询数据
     *
     * 这里使用静态对象构建数据，如果是查询数据，可以在这里进行做查询
     *
     */
    public static GraphQLFieldDefinition createGraphQLFieldDefinition(GraphQLObjectType userType) {
        return GraphQLFieldDefinition.newFieldDefinition()
                .name("User")
                .type(userType)
                // 静态数据
                .dataFetcher(new StaticDataFetcher(new User(1L, "测试", 10)))
                .build();
    }

    /**
     * 定义GraphQLObjectType对象
     * 该对象是用来做查询响应对象的名称和查询的字段的定义
     */
    public static GraphQLObjectType createGraphQLObjectType() {
        return GraphQLObjectType.newObject()
                .name("User")
                .field(GraphQLFieldDefinition.newFieldDefinition().name("id").type(Scalars.GraphQLLong))
                .field(GraphQLFieldDefinition.newFieldDefinition().name("name").type(Scalars.GraphQLString))
                .field(GraphQLFieldDefinition.newFieldDefinition().name("age").type(Scalars.GraphQLInt))
                .build();
    }

}

/**
 * 简单展示 GraphQL的查询，以及通过JavaAPI响应数据
 *
 * 传递参数进行查询
 */
public class GraphQLSimpleDemoWithArgs {


    public static void main(String[] args) {
        GraphQLObjectType userType = createGraphQLObjectType();
        GraphQLFieldDefinition userDefinition = createGraphQLFieldDefinition(userType);
        GraphQLSchema graphQLSchema = createGraphQLSchema(userDefinition);
        GraphQL graphQL = GraphQL.newGraphQL(graphQLSchema).build();

        String graph3 = "{User(id:1){id, name, age}}";
        ExecutionResult execute3 = graphQL.execute(graph3);
        // 获取结果
        System.out.println(execute3.toSpecification());
    }

    // 创建GraphQLSchema
    public static GraphQLSchema createGraphQLSchema(GraphQLFieldDefinition userDefinition) {
        GraphQLObjectType userQuery = GraphQLObjectType.newObject()
                                                               .name("userQuery")
                                                               .field(userDefinition)
                                                               .build();
        return GraphQLSchema.newSchema().query(userQuery).build();
    }

    /**
     * 创建GraphQLFieldDefinition对象
     *
     * 根据定义的查询对象做真正的查询，返回查询数据
     *
     * 这里使用静态对象构建数据，如果是查询数据，可以在这里进行做查询
     *
     */
    public static GraphQLFieldDefinition createGraphQLFieldDefinition(GraphQLObjectType userType) {
        return GraphQLFieldDefinition.newFieldDefinition()
                .name("User")
                .type(userType)
                // 设置参数查询数据
                .argument(GraphQLArgument.newArgument().name("id").type(Scalars.GraphQLLong).build())
                .dataFetcher(environment -> {
                    Long id = environment.getArgument("id");
                    return new User(id, "name" + id, id.intValue());
                })

                .build();
    }

    /**
     * 定义GraphQLObjectType对象
     * 该对象是用来做查询响应对象的名称和查询的字段的定义
     */
    public static GraphQLObjectType createGraphQLObjectType() {
        return GraphQLObjectType.newObject()
                .name("User")
                .field(GraphQLFieldDefinition.newFieldDefinition().name("id").type(Scalars.GraphQLLong))
                .field(GraphQLFieldDefinition.newFieldDefinition().name("name").type(Scalars.GraphQLString))
                .field(GraphQLFieldDefinition.newFieldDefinition().name("age").type(Scalars.GraphQLInt))
                .build();
    }
    
}