I would like to describe in detail the problems I have encountered. For example, I am going to publish an article, and this article contains not only text, but also a few pictures. If you directly request the interface, the background receives the file, after a series of processing, and return the image to the address in the server, and save it to the database together with the text message, then the problem comes now.

File upload I wrote a tool class, called this tool class, and then used jsonArry to receive the returned server address, while the backend interface continued to save the data before waiting for jsonArray to get the returned information, so every time the jsonArray was empty. After a while, the console printed out the upload completion, the return address prompt, roughly online search, all said to use thread pool, but did not specify how to use it. There is a comparison of food, but I don"t know how to read the code source. If you have done similar processing, please help me