java學習上傳和下載

小例子

上傳：

public class FileUpUtils {
    /**
     *  獲取文件的真實名稱 
     */
    public static String getRealName(String fileName) {
        int index = fileName.lastIndexOf("\\") + 1;
        return fileName.substring(index);
    }
    /**
     * 獲取隨機名稱
     */
    public static String getUUIDFileName(String fileName) {
        int index = fileName.lastIndexOf(".");
        if (index != -1) {
            //文件沒有後綴名，只返回名字
            return UUID.randomUUID().toString() + fileName.substring(index);
        } else {
            //文件有後綴名，返回隨即名字加後綴名
            return UUID.randomUUID().toString();
        }
    }
    /**
     * 目錄分離算法,例子只寫三層
     */
    public static String getRandomDirectory(String fileName){
        int hashcode = fileName.hashCode();
        int a = hashcode & 0xf;
        hashcode = hashcode >>> 4;
        int b = hashcode & 0xf;
        hashcode = hashcode >>> 4;
        int c = hashcode & 0xf;
        return "/" + a + "/" + b + "/" + c;
    }
}

---

public class UpLoad5 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        DiskFileItemFactory factory = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(factory);
        boolean flag = upload.isMultipartContent(request);
        if (flag) {
            response.getWriter().write("是文件上傳");
            upload.setHeaderEncoding("utf-8");
            try {
                List<FileItem> item = upload.parseRequest(request);
                for (FileItem items : item) {
                    if (!items.isFormField()) {
                        //上傳文件名稱
                        String name = items.getName();
                        //文件名字
                        String fileName = FileUpUtils.getRealName(name);
                        //隨機名字
                        String  uuidName = FileUpUtils.getUUIDFileName(fileName);
                        //隨機目錄
                        String randomDirectory = FileUpUtils.getRandomDirectory(fileName);

                        String path = this.getServletContext().getRealPath("/upload");

                        File f = new File(path , randomDirectory);
                        if(!f.exists()){
                            f.mkdirs();
                        }

                        InputStream in = items.getInputStream();
                        FileOutputStream fos = new FileOutputStream(new File(f , uuidName));
                        name.substring(name.lastIndexOf("\\") + 1);

                        IOUtils.copy(in, fos);

                        fos.close();
                        in.close();
                        //刪除臨時文件
                        items.delete();
                    }
                }
            } catch (FileUploadException e) {
                response.getWriter().write(e.getMessage());
                return;
            }
        } else {
            System.out.println("不是文件上傳操作");
            return;
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

下載：

public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

    // 1.得到要下載 的文件名稱
    String filename = request.getParameter("filename");

    filename = new String(filename.getBytes("iso8859-1"), "utf-8");// 解決中文亂碼

    // 2.在d:/upload目錄下查找這個文件是否存在
    File file = new File("d:/upload/" + filename);

        // /文件存在，完成下載
    if (file.exists()) {

        // 下載注意事項1--設置下載文件的mimeType
        String mimeType = this.getServletContext().getMimeType(filename);
        response.setContentType(mimeType);

        String agent = request.getHeader("user-agent");
        if (agent.contains("MSIE")) {
            // IE瀏覽器
            filename = URLEncoder.encode(filename, "utf-8");

        } else if (agent.contains("Firefox")) {
            // 火狐瀏覽器
            BASE64Encoder base64Encoder = new BASE64Encoder();
            filename = "=?utf-8?B?"
                    + base64Encoder.encode(filename.getBytes("utf-8"))
                    + "?=";
        } else {
            // 其它瀏覽器
            filename = URLEncoder.encode(filename, "utf-8");
        }

        // 下載注意事項2--永遠是下載
        response.setHeader("content-disposition", "attachment;filename="
                + filename);

        FileInputStream fis = new FileInputStream(file); // 讀取要下載文件的內容
        OutputStream os = response.getOutputStream(); // 將要下載的文件內容通過輸出流寫回到瀏覽器端.
        int len = -1;
        byte[] b = new byte[1024 * 100];

        while ((len = fis.read(b)) != -1) {
            os.write(b, 0, len);
            os.flush();
        }
        os.close();
        fis.close();

    } else {
        throw new RuntimeException("下載資源不存在.");
    }
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    doGet(request, response);
}