如何使用Apollo Express为Graphql后端中的特定解析器设置中间件？

const express = require('express');
const { ApolloServer } = require('apollo-server-express');

const { makeExecutableSchema } = require('graphql-tools');
const typeDefs = `
  type Query {
    hello: String
  }
`;
const resolvers = {
  Query: {
    hello: () => 'Hello, World!'
  }
};
const schema = makeExecutableSchema({ typeDefs, resolvers });

const server = new ApolloServer({ schema });

const customResolver = {
  Query: {
    hello: () => 'Custom Hello!'
  }
};

const app = express();
server.applyMiddleware({
  app,
  path: '/graphql',
  bodyParserConfig: true,
  introspection: true,
  playground: true,
  plugins: [
    {
      requestDidStart: () => ({
        didResolveOperation({ request, document }) {
          const operationName = request.operationName;
          if (operationName === 'hello') {
            // 添加你的中间件逻辑
            console.log('中间件处理特定解析器：hello');
          }
        },
      }),
    },
  ],
});

app.listen({ port: 4000 }, () => {
  console.log('Apollo Express服务器已启动！');
});