Java Spring 如何进行多线程操作并等待完成

Question

So I have a get operation where a user supplys a list of items. For each item in the list I need to make an API call which is what takes the most time in my application.

Lets say the flow is List -> Operation A -> Operation B ( API Call ) -> Operation C

So instead of processing all the items in the list sequentially, I was thinking if I could create multiple threads. All the threads would have to finish Operation B before Operation C starts. Operations A and C don't need to be multithreaded.

Is there a straightforward way to do this?

Answer 1

You could try to use CompletableFuture for this, something along the lines of:

   ExecutorService executorService = Executors.newFixedThreadPool(3);

   CompletableFuture<?>[] all =
   youList.stream()
          .map(x -> CompletableFuture.supplyAsync(() -> operationA(x))
                       .thenApplyAsync(YourClass::operationB)
                       .thenApplyAsync(YouClass::operationC))
            .toArray(x -> new CompletableFuture[0]);

    CompletableFuture.allOf(all);