文件上传和下载

一般文件上传并不会放在数据库上，我这是为了测试一下咯

if ("post".equalsIgnoreCase(request.getMethod())) {
        DiskFileUpload diskFileUpload = new DiskFileUpload();//文件上传的类
        diskFileUpload.setHeaderEncoding("UTF-8");//设置utf-8
        List<FileItem> list = diskFileUpload.parseRequest(request);//解析request
        for (FileItem fileItem : list) {
            if (!fileItem.isFormField()) {
                String filename = fileItem.getName().replace("\", "/");//
                filename = filename
                        .substring(filename.lastIndexOf("/") + 1);//拼接名字
                Connection con = null;
                PreparedStatement preparedStatement = null;
                try {
                    String sql = "insert into blobTest values(?,?,?)";
                    con = DbManager.getConnection();
                    preparedStatement = con.prepareStatement(sql);
                    preparedStatement.setString(1, filename);//第一个参数和第二个参数放名字和文件类型
                    preparedStatement.setString(2,
                            fileItem.getContentType());
                    preparedStatement.setBinaryStream(3,
                            fileItem.getInputStream(),//fileItem直接打开流输入进去
                            (int) fileItem.getSize());
                    preparedStatement.executeUpdate();
                } 

下载类

in1 = resultSet.getBinaryStream("file");//从数据库获得字段名为file的文件
out1 = response.getOutputStream();