java - 通过socket继续中断的下载

Question

我正在尝试继续从服务器到客户端的中断下载。

发送的服务器代码:

long fileLength = file.length();
        String fileName = file.getName();
        int bytesRead = 0;
        long bytesReadAmount = 0;
        byte[] byteArray = new byte[6 * PACKET_SIZE];

        OutputStream outputStream = socket.getOutputStream();

        try {
            BufferedInputStream bufferedIS = new BufferedInputStream(new FileInputStream(file));
            while ((bytesRead = bufferedIS.read(byteArray)) > 0) {
                outputStream.write(byteArray, (int)existingFileSize, bytesRead);
                bytesReadAmount += bytesRead;
                System.out.println("File sending " + fileName + " (send" + bytesReadAmount + " byte, remain " +
                        (fileLength - bytesReadAmount));
            }
            System.out.println("File transfer end");
        } catch (IOException e) {
            System.out.println("File transfer error");
            e.printStackTrace();
        } finally {
            dataOS.flush();
            socket.close();
        }

客户端接收代码

long bytesReadAmount = 0;
        int bytesRead = 0;
        long size = 0;
        byte[] byteArray = new byte[6 * Server.PACKET_SIZE];

        try {
            File file = new File(DIRECTORY_PATH + fileName);
            file.createNewFile();
            FileOutputStream fileOS = new FileOutputStream(file);
            BufferedOutputStream bufferedOS = new BufferedOutputStream(fileOS);

            while ((bytesRead = dataIS.read(byteArray)) != -1) {
                bufferedOS.write(byteArray, (int)existingFileSize, bytesRead);
                bytesReadAmount += bytesRead;
                System.out.println("File receiving " + fileName + " (" + bytesReadAmount + " bytes received)");
            }
            System.out.println("File " + fileName + " sending OK");
        } catch (IOException e) {
            System.out.println("Connection interrupted");
            e.printStackTrace();
        }
    }

从头到尾发送大文件效果很好，但中断后继续下载却不行(当我尝试继续中断的文件时，发送不起作用)。另外，当我发送完整文件时，副本的大小与原始文件的某些字节不同。请帮忙解决这个问题

Answer 1

您在 write(byteArray, (int)existingFileSize, bytesRead) 中使用的 offset 是 byteArray 中的偏移量，而不是原始偏移量文件。我建议您使用 skip() 跳过要读取或写入的数据，并在重新启动时附加到文件(通过在 FileOutputStream 构造函数中设置附加)