.NET中如何将存入数据库中的二进制文件读取出来

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解决时间 2021-06-05 15:48

提问者网友：聂風
2021-06-05 09:10

我把一个压缩文件用二进制写入SQLserver数据库,但是要怎么把二进制数据读取出来，转化成压缩文件，求解

最佳答案

五星知识达人网友：青灯有味
2021-06-05 09:32

、建所需数据库和表，语句如下：

--建立数据库
create database test

--使用该数据库
use test

--建立存放图片的表
create table piclist(
id int Identity primary key,
pic Image not null
)

2、制作上传图片的模块，代码如下：
前台html代码：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="UpPhoto.aspx.cs" Inherits="Test_UpPhoto" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" " http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns=" http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>无标题页</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<input id="UpPhoto" name="UpPhoto" runat="server" type="file" />
<asp:Button id="btnAdd" runat="server" Text="上传" OnClick="btnAdd_Click"></asp:Button>
</div>
</form>
</body>
</html>

后台代码：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Data.SqlClient;

public partial class Test_UpPhoto : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}

protected void btnAdd_Click(object sender, EventArgs e)
{
//获得图象并把图象转换为byte[]
HttpPostedFile upPhoto = UpPhoto.PostedFile;
int upPhotoLength = upPhoto.ContentLength;
byte[] PhotoArray = new Byte[upPhotoLength];
Stream PhotoStream = upPhoto.InputStream;
PhotoStream.Read(PhotoArray, 0, upPhotoLength);

//连接数据库
string ConStr = "server=(local);user id=sa;pwd=sa;database=test";
SqlConnection conn = new SqlConnection(ConStr);

string strSql = "Insert into piclist(pic) values(@pic)";
SqlCommand cmd = new SqlCommand(strSql, conn);
cmd.Parameters.Add("@pic", SqlDbType.Image);
cmd.Parameters["@pic"].Value = PhotoArray;

conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
Response.Write("图片上传成功");
}
}

3、制作显示图片的模块(单独显示图片，即没用到datalist)：
后台代码：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.IO;

public partial class Test_ShowPhoto : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if(!Page.IsPostBack)
{
//连接数据库
string ConnStr = "server=(local);user id=sa;pwd=sa;database=test";
string strSql = "select * from piclist";
SqlConnection conn = new SqlConnection(ConnStr);
conn.Open();

SqlCommand cmd=new SqlCommand(strSql,conn);
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
Response.ContentType = "application/octet-stream";
Response.BinaryWrite((Byte[])reader["pic"]);
Response.Write("successful");
}
reader.Close();
conn.Close();
Response.End();
}
}
}

补充步骤3，用datalist显示图片方法：
建立两个asp.net 页面，名称为piclist.aspx和StreamImg.aspx。
piclist.aspx前台代码为：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="piclist.aspx.cs" Inherits="Test_Test" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" " http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns=" http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>无标题页</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DataList ID="dlContent" runat="server" Width="554px">
<ItemTemplate>
<table cellpadding="0" cellspacing="0">
<tr>
<td >
<img id='img1' src='StreamImg.aspx?id= <%# DataBinder.Eval(Container.DataItem,"id") %>'>
</a>
</a>
</td>
</tr>
</table>
</ItemTemplate>
</asp:DataList>
</div>
</form>
</body>
</html>

piclist.aspx后台代码为：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.IO;

public partial class Test_Test : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
//连接数据库
string ConnStr = "server=(local);user id=sa;pwd=sa;database=test";
SqlConnection sqlcon = new SqlConnection(ConnStr);
sqlcon.Open();
string sqlstr = "select id from piclist";
SqlDataAdapter MyAdapter = new SqlDataAdapter(sqlstr, sqlcon);
DataSet ds = new DataSet();
MyAdapter.Fill(ds, "tb_pic");
this.dlContent.DataSource = ds;
this.dlContent.DataBind();
sqlcon.Close();
}
}
}

StreamImg.aspx无前台代码，后台代码为：
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;
using System.IO;

public partial class StreamImg : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
//string type = Request.QueryString["pt"];
int id = Convert.ToInt32(Request.QueryString["id"]);
ShowPic(id);
}
private void ShowPic(int id)
{
//连接数据库
string ConnStr = "server=(local);user id=sa;pwd=sa;database=test";
string strSql = "select * from piclist where id='"+ id +"'";
SqlConnection conn = new SqlConnection(ConnStr);
conn.Open();

SqlCommand cmd = new SqlCommand(strSql, conn);
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
Response.ContentType = "application/octet-stream";
Response.BinaryWrite((Byte[])reader["pic"]);
Response.Write("successful");
}
reader.Close();
conn.Close();
Response.End();
}
} 9

回答者： pgdoryoku - 见习主管五级

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2021-06-05 11:10

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