java 实现断点续传的上传功能

下面是一个简单的实现Java断点续传上传功能的代码示例，其中使用了HttpURLConnection和RandomAccessFile类：

public class ResumableUploader {
    private static final int BUFFER_SIZE = 4096;
    private static final String FILE_PATH = "yourFilePath";
    private static final String UPLOAD_URL = "yourUploadUrl";
    private static final int MAX_NUM_RETRIES = 5;
    public static void main(String[] args) throws Exception {
        File file = new File(FILE_PATH);
        // 获取文件大小
        long fileSize = file.length();
        // 创建 HttpURLConnection
        HttpURLConnection conn = (HttpURLConnection) new URL(UPLOAD_URL).openConnection();
        // 设置请求头信息
        conn.setRequestMethod("POST");
        conn.setConnectTimeout(10000);
        conn.setReadTimeout(10000);
        conn.setDoOutput(true);
        conn.setRequestProperty("Content-Type", "application/octet-stream");
        conn.setRequestProperty("Content-Length", String.valueOf(fileSize));
        // 获取已上传的文件大小
        long uploadedSize = 0L;
        String range = conn.getRequestProperty("Range");
        if (range != null) {
            String[] rs = range.substring("bytes=".length()).split("-");
            uploadedSize = Long.parseLong(rs[0]);
        }
        // 设置请求体
        OutputStream os = conn.getOutputStream();
        RandomAccessFile raf = new RandomAccessFile(file, "r");
        raf.seek(uploadedSize);
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead;
        while ((bytesRead = raf.read(buffer)) != -1) {
            os.write(buffer, 0, bytesRead);
        }
        os.close();
        raf.close();
        // 处理响应
        int responseCode = conn.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_CREATED) {
            System.out.println("文件上传成功！");
        } else {
            System.out.println("文件上传失败，响应码：" + responseCode);
            int numRetries = 0;
            while (responseCode >= 500 && responseCode < 600 && numRetries < MAX_NUM_RETRIES) {
                System.out.println("服务器错误，正在重新上传...");
                Thread.sleep(5000);
                conn = (HttpURLConnection) new URL(UPLOAD_URL).openConnection();
                conn.setRequestProperty("Content-Type", "application/octet-stream");
                conn.setRequestProperty("Content-Length", String.valueOf(fileSize));
                conn.setRequestProperty("Range", "bytes=" + uploadedSize + "-");
                os = conn.getOutputStream();
                raf = new RandomAccessFile(file, "r");
                raf.seek(uploadedSize);
                buffer = new byte[BUFFER_SIZE];
                bytesRead = 0;
                while ((bytesRead = raf.read(buffer)) != -1) {
                    os.write(buffer, 0, bytesRead);
                }
                os.close();
                raf.close();
                responseCode = conn.getResponseCode();
                numRetries++;
            }
            if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_CREATED) {
                System.out.println("文件上传成功！");
            } else {
                System.out.println("文件上传失败，响应码：" + responseCode);
            }
        }
    }
}

注：该代码仅供参考，实际使用时需要根据具体业务需求进行修改。

参考文章：http://blog.ncmem.com/wordpress/2023/10/23/java-实现断点续传的上传功能/