SpringMvc: StreamResponseBody的用法

package cn.edu.tju.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;

import java.io.IOException;
import java.io.OutputStream;

@RestController
public class DownloadController {
    @GetMapping("/download")
    public StreamingResponseBody handle() {
        return new StreamingResponseBody() {
            @Override
            public void writeTo(OutputStream outputStream) throws IOException {
                outputStream.write("this is a book".getBytes());
            }
        };
    }
}