在Microsoft SQL Server2008以后的版本中,将删除image数据类型。在新的开发工作中将不适用此数据类型,并打算修改当前使用此数据类型的应用程序,改用varbinary(max)数据类型。
ASP.NET向SQL Server导入文件主要用到FileUpload控件的FileBytes属性。该属性从FileUpload控件所指定的文件返回一个字节数组 。
1.数据库准备
为了方便大家能够理解,这里我们只设计两个字段,一个是文件类型字段,字段名为FileType,另一个是存放文件内容字段,字段名为FileContent。创建数据库
,数据库名为VarFile,语句如下:
CREATE DATABASE VARFILE
GO
创建表,表名为FileInOut,语句如下:
USE VARFILE
GO
CREATE TABLE FILEINTOU
(
FileType nvarchar(30) not null,
FileContent varbinary(max) null
)
2.添加控件
运行VS2008并新建一个网站,在页面Default.aspx中添加一个FileUpload控件,ID 为FileUpload1.同时添加三个Button按钮,ID分别为fileUp和fileLoad。Text属性分别设置为“上传文件”和“下载文件”。
3.添加代码
(1)添加命名空间,因为和SQL Server数据库连接,所以添加using System.Data.Sqlclient和using System.Data命名空间。又因为要设置输出流的HTTP的字符集为"gb2312"字符编码,所以添加using System.Text命名空间。同时又因为要把导出文件强类型化为字符串,所以添加using System.Collections.Specialized命名空间。
(2)添加“上传文件”按钮的事件代码。当单击“上传文件”按钮后,获取FileUpload控件所选择的文件的文件类型以及文件的字节数组插入数据库中。切换到设计视图,双击“上传文件”按钮,添加"上传文件"按钮事件代码,代码如下:
代码如下:
protected void fileUp_Click(object sender,EventArgs e)
{
if(FileUpload1.FileName==string.Empty)
{
Response.Write("<script>altert(‘请选择要上传的文件')</script>");
return;
}
string mailto:connstr=@%22Data Source=69F638102711447\SQL2008;Initial Catalog=VarFile;Integrated Security=Ture"; //数据库连接字符串
string the Selected=FileUpload1.FileName; //获取上传文件的后缀名
string extension=theSelected.Substring(theSelected.LastIndexOf(".")).ToLower();
if(CheckFileType(extension)) //如果有指定的文件类型
{
string contentType=GetContentType(extension);
string sqlstr="insert into FileInOut values(@FileType,@FileCount)"; //上传文件的SQL语句
string sqlstrclear="truncate table FileInOut"; //清空数据库SQL语句
SqlConnection con=new SqlConnection(connstr); //实例化数据库连接对象
SqlCommand cmd=new SqlCommand(sqlstr,con); //实例化上传文件SQL命令
SqlCommand cmdclear=new SqlCommand(sqlstrclear,con); //实例化清空数据库SQL命令
//定义问价类型参数
cmd.Parameters.Add(new SqlParameter("@FileType”,SlqDbType.NvarChar,30));
cmd.Parameters["@FileType"].Value=contentType; //定义文件内容参数
cmd.Parameters.Add(new SqlParameter("@FileCount",SqlDbType.NVarChar,30)); //将文件转化为字节数组作为@FileCount的值
cmd.Parameters["@FileCount"].Value=FileUpload1.FileBytes;
con.Open();
cmdclear.ExecuteNonQuery(); //执行清空数据库命令
cmd.ExecuteNonQuery(); //执行上传文件命令
}
}
(3)添加获取文件类型和获得文件导出方式的函数方法。首先查看所要上传文件类型是否在指定问价类型内,如果在,则可以直接导入文件,然后根据文件类型
获取此文件导出方式并存放在FileType字段中,代码如下:
代码如下:
public static bool CheckFileType(string type)
{
StringDictionary sd=new StringDictionary(); //实例化集合StringDictionary类
sd.Add(".doc","application/msword");
sd.Add(".ppt","application/vnd.ms-powerpoint");
sd.Add(".xsl","application/vnd.ms-excel");
sd.Add(".rtf","application/msword");
sd.Add(".html","text/html");
sd.Add(".htm","text/html");
sd.Add(".txt","text/plain");
sd.Add(".pdf","application/pdf");
return sd.ContainsKey(type); //确定StringDictionary是否包含特定键
}
public static string GetContentType(string extension) //获取输出文件方式
{StringDictionary sd=new StringDictionary();
sd.Add(".doc","application/msword");
sd.Add(".ppt","application/vnd.ms-powerpoint");
sd.Add(".xsl","application/vnd.ms-excel");
sd.Add(".rtf","application/msword");
sd.Add(".html","text/html");
sd.Add(".htm","text/html");
sd.Add(".txt","text/plain");
sd.Add(".pdf","application/pdf");
return sd[extension]; //返回对应键的值
}
(4)上传文件,选择一个pdf文件,单击"上传文件"按钮后,打开数据库中的FileInOut表,如图所示可以看到。

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