使用SimpleGraphQLServlet的GraphQL订阅

Question

我创建了一个Java应用程序来实现GraphQL服务器。工作正常。现在，我要添加订阅。我读过我必须实现一个Websocket，但我不明白如何使用SimpleGraphQLServlet。

这是我到目前为止的代码：

@WebServlet("/graphql") public class GraphQLEndpoint extends HttpServlet {

SimpleGraphQLServlet graphQLServlet;

@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    graphQLServlet.service(req, resp);
}

@Override
public void init() throws ServletException {
        graphQLServlet = SimpleGraphQLServlet.builder(buildSchema()).build();
}

private GraphQLSchema buildSchema() { 

    AllRepositories reps = new AllRepositories();

    Queries queries = new Queries(reps);

    return new GraphQLSchemaGenerator()
        .withOperationsFromSingletons(queries) 
        .generate(); 

}}

这些是我的依赖项：

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

<dependency>
    <groupId>com.graphql-java</groupId>
    <artifactId>graphql-java-tools</artifactId>
    <version>5.2.4</version>
</dependency>

<dependency>
    <groupId>com.graphql-java</groupId>
    <artifactId>graphql-java-servlet</artifactId>
    <version>5.2.0</version>
</dependency>

<dependency>
    <groupId>io.leangen.graphql</groupId>
    <artifactId>spqr</artifactId>
    <version>0.9.1</version>
</dependency>

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
    <scope>provided</scope>
</dependency>