Spring Boot 2-WebClient：从一个控制器调用多个Rest API

Question

我正在使用Spring Boot微服务，并致电下游获取数据。

要求从多个下游获取数据，并将响应聚合为单个响应。

有人可以帮助我如何在Get请求中进行并行rest调用吗。

下面是我可以一个接一个地调用that的简单方法。但是，我正在寻找并行调用。

@RestController
Class{

@GetMapping
method(){
    req1 = endpoint1;
    req2 = endpoint2;

    response = req1+req2; //How to achieve this using parallel processing.
}

请协助。谢谢

Answer 1

有很多方法可以实现并行执行。

一种方法可能是使用流：

// First prepare tasks you want to run in parallel
List<Supplier<Result>> tasks = new ArrayList<>();
tasks.add(() -> {
    Result result = // get result from WebClient
    return result;
});

// Next execute in parallel all tasks and collect results
List<Result> results = tasks.parallelStream()
        .map(Supplier::get)
        .collect(Collectors.toList());

// Merge results into one

当然，如果您想更好地控制线程（一次可以并行运行多少任务，不必为每个endpoint调用生成新线程等），那么由于您使用的是Spring Boot，您可以使用例如AsyncTaskExecutor

class MyAwesomeController {
    private final AsyncTaskExecutor executor;

    public MyAwesomeController() {
        executor = new TaskExecutorBuilder()
                .corePoolSize(5) // how many threads to keep alive
                .maxPoolSize(20) // how many max threads (taks) can be executed at one
                // Some other settings (eg. how long to keep idle thread alive etc.
                .build();
    }

    public Result endpoint() {
        // First prepare tasks you want to run in parallel
        List<Future<Result>> tasks = new ArrayList<>();
        tasks.add(executor.submit(() -> {
            Result result = // get result from WebClient
            return result;
        }));

        // Next collect results from Future
        List<Result> results = tasks.stream()
                .map(Future::get)
                .collect(Collectors.toList());
        
        // Merge results into one
    }

}

有关遗嘱执行人的更多信息，请参见：https://www.baeldung.com/java-executor-service-tutorial