没写过，你试试chatgpt的回答吧

import java.io.IOException;
import java.io.OutputStream;
import java.util.function.Consumer;

public class TimedOutputStream extends OutputStream {
    private final OutputStream delegate;
    private final Consumer<Long> completionCallback;
    private final long startTime;

    public TimedOutputStream(OutputStream delegate, Consumer<Long> completionCallback) {
        this.delegate = delegate;
        this.completionCallback = completionCallback;
        this.startTime = System.currentTimeMillis();
    }

    @Override
    public void write(int b) throws IOException {
        delegate.write(b);
    }

    @Override
    public void close() throws IOException {
        delegate.close();
        long endTime = System.currentTimeMillis();
        long timeConsumed = endTime - startTime;
        completionCallback.accept(timeConsumed);
    }
}


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

import java.io.OutputStream;
import java.util.concurrent.Executors;

@RestController
@RequestMapping("/download")
public class FileDownloadController {

    @GetMapping("/stream")
    public ResponseBodyEmitter streamData() {
        ResponseBodyEmitter emitter = new ResponseBodyEmitter();

        // Wrap the emitter's OutputStream with the TimedOutputStream
        OutputStream outputStream = new TimedOutputStream(emitter.getOutputStream(),
            timeConsumed -> {
                // Handle completion here, e.g., logging the time consumed
                System.out.println("Time consumed: " + timeConsumed + " ms");
            });

        // Simulate streaming data (replace with your actual data source)
        Executors.newSingleThreadExecutor().submit(() -> {
            try {
                for (int i = 0; i < 10; i++) {
                    outputStream.write(("Data " + i + "\n").getBytes());
                    Thread.sleep(500); // Simulate data processing
                }
            } catch (Exception e) {
                emitter.completeWithError(e);
            } finally {
                try {
                    outputStream.close();
                } catch (IOException e) {
                    emitter.completeWithError(e);
                }
            }
            emitter.complete();
        });

        return emitter;
    }
}



【 在 feng321 的大作中提到: 】
: 能给个可以跑的样例代码吗？真是不太会。。。。
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