java大文件斷點續(xù)傳

上傳大文件經(jīng)常遇到上傳一半由于網(wǎng)絡(luò)或者其他一些原因上傳失敗摧扇。然后又得重新上傳（很麻煩），所以就想能不能做個斷點上傳的功能殴泰。于是網(wǎng)上搜索于宙，發(fā)現(xiàn)市面上很少有斷點上傳的案例，有找到一個案例也是采用SOCKET作為上傳方式（大文件上傳悍汛，不適合使用POST,GET形式）捞魁。由于大文件夾不適合http上傳的方式，所以就想能不能把大文件切割成n塊小文件离咐，然后上傳這些小文件谱俭，所有小文件全部上傳成功后再在服務(wù)器上進(jìn)行拼接。這樣不就可以實現(xiàn)斷點上傳健霹，又解決了http不適合上傳大文件的難題了嗎Ｍ稀！糖埋！

服務(wù)端：
需要寫兩個接口
接口一：根據(jù)上傳文件名稱filename 判斷是否之前上傳過宣吱，沒有則返回客戶端chunck=1，有則讀取記錄chunck并返回瞳别。

接口二：上傳文件征候，如果上傳塊數(shù)chunck=chuncks，遍歷所有塊文件拼接成一個完整文件祟敛。

接口一代碼如下：

@WebServlet(urlPatterns = { "/ckeckFileServlet" })
public class CkeckFileServlet extends HttpServlet {

    private FileUploadStatusServiceI statusService;
    String repositoryPath;
    String uploadPath;

    @Override
    public void init(ServletConfig config) throws ServletException {
        ServletContext servletContext = config.getServletContext();
        WebApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(servletContext);
        statusService = (FileUploadStatusServiceI) context.getBean("fileUploadStatusServiceImpl");

        repositoryPath = FileUtils.getTempDirectoryPath();
        uploadPath = config.getServletContext().getRealPath("datas/uploader");
        File up = new File(uploadPath);
        if (!up.exists()) {
            up.mkdir();
        }
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub

        String fileName = new String(req.getParameter("filename"));
        //String chunk = req.getParameter("chunk");
        //System.out.println(chunk);
        System.out.println(fileName);
        resp.setContentType("text/json; charset=utf-8");

        TfileUploadStatus file = statusService.get(fileName);

        try {
            if (file != null) {
                int schunk = file.getChunk();
                deleteFile(uploadPath + schunk + "_" + fileName);
                //long off = schunk * Long.parseLong(chunkSize);
                resp.getWriter().write("{\"off\":" + schunk + "}");

            } else {
                resp.getWriter().write("{\"off\":1}");
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

接口二代碼如下：

@WebServlet(urlPatterns = { "/uploaderWithContinuinglyTransferring" })
public class UploaderServletWithContinuinglyTransferring extends HttpServlet {

    private static final long serialVersionUID = 1L;

    private FileUploadStatusServiceI statusService;
    String repositoryPath;
    String uploadPath;

    @Override
    public void init(ServletConfig config) throws ServletException {
        ServletContext servletContext = config.getServletContext();
        WebApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(servletContext);
        statusService = (FileUploadStatusServiceI) context.getBean("fileUploadStatusServiceImpl");

        repositoryPath = FileUtils.getTempDirectoryPath();
        System.out.println("臨時目錄：" + repositoryPath);
        uploadPath = config.getServletContext().getRealPath("datas/uploader");
        System.out.println("目錄：" + uploadPath);
        File up = new File(uploadPath);
        if (!up.exists()) {
            up.mkdir();
        }
    }

    @SuppressWarnings("unchecked")
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setCharacterEncoding("UTF-8");
        Integer schunk = null;// 分割塊數(shù)
        Integer schunks = null;// 總分割數(shù)
        String name = null;// 文件名
        BufferedOutputStream outputStream = null;
        if (ServletFileUpload.isMultipartContent(request)) {
            try {
                DiskFileItemFactory factory = new DiskFileItemFactory();
                factory.setSizeThreshold(1024);
                factory.setRepository(new File(repositoryPath));// 設(shè)置臨時目錄
                ServletFileUpload upload = new ServletFileUpload(factory);
                upload.setHeaderEncoding("UTF-8");
                upload.setSizeMax(5 * 1024 * 1024 * 1024);// 設(shè)置附近大小
                List<FileItem> items = upload.parseRequest(request);
                // 生成新文件名

                String newFileName = null; 
                for (FileItem item : items) {
                    if (!item.isFormField()) {// 如果是文件類型
                        name = newFileName;// 獲得文件名
                        if (name != null) {
                            String nFname = newFileName;
                            if (schunk != null) {
                                nFname = schunk + "_" + name;
                            }
                            File savedFile = new File(uploadPath, nFname);
                            item.write(savedFile);
                        }
                    } else {
                        // 判斷是否帶分割信息
                        if (item.getFieldName().equals("chunk")) {
                            schunk = Integer.parseInt(item.getString());
                            //System.out.println(schunk);
                        }
                        if (item.getFieldName().equals("chunks")) {
                            schunks = Integer.parseInt(item.getString());
                        }

                        if (item.getFieldName().equals("name")) {
                            newFileName = new String(item.getString());

                        }

                    }

                }
                //System.out.println(schunk + "/" + schunks);
                if (schunk != null && schunk == 1) {
                    TfileUploadStatus file = statusService.get(newFileName);
                    if (file != null) {
                        statusService.updateChunk(newFileName, schunk);
                    } else {
                        statusService.add(newFileName, schunk, schunks);
                    }

                } else {
                    TfileUploadStatus file = statusService.get(newFileName);
                    if (file != null) {
                        statusService.updateChunk(newFileName, schunk);
                    }
                }
                if (schunk != null && schunk.intValue() == schunks.intValue()) {
                    outputStream = new BufferedOutputStream(new FileOutputStream(new File(uploadPath, newFileName)));
                    // 遍歷文件合并
                    for (int i = 1; i <= schunks; i++) {
                        //System.out.println("文件合并:" + i + "/" + schunks);
                        File tempFile = new File(uploadPath, i + "_" + name);
                        byte[] bytes = FileUtils.readFileToByteArray(tempFile);
                        outputStream.write(bytes);
                        outputStream.flush();
                        tempFile.delete();
                    }
                    outputStream.flush();
                }
                response.getWriter().write("{\"status\":true,\"newName\":\"" + newFileName + "\"}");
            } catch (FileUploadException e) {
                e.printStackTrace();
                response.getWriter().write("{\"status\":false}");
            } catch (Exception e) {
                e.printStackTrace();
                response.getWriter().write("{\"status\":false}");
            } finally {
                try {
                    if (outputStream != null)
                        outputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

關(guān)鍵點：
1 需要與數(shù)據(jù)庫交互疤坝，數(shù)據(jù)庫存放文件名，第幾塊馆铁，總共幾塊這幾個字段
2 上傳時先調(diào)用接口一跑揉，通過文件名查詢數(shù)據(jù)，如果有數(shù)據(jù)埠巨，則表示接下來要續(xù)傳历谍，接著調(diào)用第二個接口進(jìn)行上傳剩下的文件塊
3 如果沒有數(shù)據(jù)則表示是新文件上傳，調(diào)用接口二辣垒，從第一塊開始上傳望侈，接口二主要作用記錄并更新文件的上傳信息（數(shù)據(jù)庫數(shù)據(jù)），在滿足當(dāng)前上傳區(qū)塊等于總塊數(shù)時進(jìn)行合并文件勋桶。

另外數(shù)據(jù)庫新建表可以執(zhí)行如下數(shù)據(jù)庫語句
DROP TABLE IF EXISTS sys_file_upload_status;
CREATE TABLE sys_file_upload_status (
obj_id varchar(36) NOT NULL,
file_name varchar(1000) DEFAULT NULL,
chunk int(11) DEFAULT NULL,
chunks int(11) DEFAULT NULL,
PRIMARY KEY (obj_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

數(shù)據(jù)庫交互大家使用自己熟悉的方式即可脱衙，比如jdbc侥猬，hibernate，mybatis等等捐韩，哪個好用用哪個退唠。