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c# 讀取Northwind數(shù)據(jù)庫(kù)image字段

更新時(shí)間：2009年03月13日 22:36:36 作者：

我在寫(xiě)一個(gè)三層結(jié)構(gòu)Demo時(shí)，使用了Northwind這個(gè)范例數(shù)據(jù)庫(kù)。但是奇怪的是，讀取Categories表的Picture列（image類型）無(wú)法在image控件中正常顯示(解決方案在后面代碼中可以看到)。

這里值得一提的是，web控件image不像winForm控件那樣可以通過(guò)讀取二進(jìn)制流賦值給image屬性來(lái)顯示圖像?？梢酝ㄟ^(guò)變通的方法來(lái)實(shí)現(xiàn)，流行的做法是新建一個(gè)頁(yè)面專門(mén)用來(lái)顯示圖像，這里代碼直接用孟子E章前輩的（作了小修改，主要是剔除78個(gè)byte字節(jié)流來(lái)正常顯示northwind數(shù)據(jù)庫(kù)的圖片）：
ReadImage.aspx.cs

復(fù)制代碼代碼如下:

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; 

namespace WebApplication2 
{ 
public partial class ReadImage : System.Web.UI.Page 
{ 
protected void Page_Load(object sender, EventArgs e) 
{ 
string strImageID = Request.QueryString["id"]; 
SqlConnection myConnection = new SqlConnection("Data Source=.;Initial Catalog=northwind;User Id=sa;Password=123456;"); 
SqlCommand myCommand = new SqlCommand("Select Picture from Categories Where CategoryID=" 
+ strImageID, myConnection); 

try 
{ 
myConnection.Open(); 
SqlDataReader myDataReader; 
myDataReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection); 
if (myDataReader.Read()) 
{ 
Response.Clear(); 

Response.ContentType = "image/jpeg"; 
byte[] b = (byte[])myDataReader["Picture"]; 
//下面的方法就是用來(lái)讓圖片可以正常顯示 
byte[] temp=new byte [b.Length -78]; 
Array.Copy(b, 78, temp, 0, b.Length - 78); 
Response.BinaryWrite(temp); 
} 
myConnection.Close(); 
} 
catch (SqlException SQLexc) 
{ 
Response.Write(SQLexc.ToString ()); 
} 
Response.End(); 

} 
} 
}

在源頁(yè)面如Default.aspx.cs可以通過(guò)下面方法調(diào)用

復(fù)制代碼代碼如下:

protected void Page_Load(object sender, EventArgs e) 
{ 
if(!IsPostBack ) 
Image1.ImageUrl = FormatURL("1"); 

} 
protected string FormatURL(string strArgument) 
{ 
return "ReadImage.aspx?id=" + strArgument; 
}

如果不想新建一個(gè)頁(yè)面來(lái)承載圖像，也可以使用下面的方法：（注意：下面的類是自定義的，大家看得懂這個(gè)方法就可以了）

復(fù)制代碼代碼如下:

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; 

namespace WebApplication2 
{ 
public partial class ReadImage : System.Web.UI.Page 
{ 
protected void Page_Load(object sender, EventArgs e) 
{ 
string strImageID = Request.QueryString["id"]; 
SqlConnection myConnection = new SqlConnection("Data Source=.;Initial Catalog=northwind;User Id=sa;Password=123456;"); 
SqlCommand myCommand = new SqlCommand("Select Picture from Categories Where CategoryID=" 
+ strImageID, myConnection); 

try 
{ 
myConnection.Open(); 
SqlDataReader myDataReader; 
myDataReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection); 
if (myDataReader.Read()) 
{ 
Response.Clear(); 

Response.ContentType = "image/jpeg"; 
byte[] b = (byte[])myDataReader["Picture"]; 
byte[] temp=new byte [b.Length -78]; 
Array.Copy(b, 78, temp, 0, b.Length - 78); 
Response.BinaryWrite(temp); 
} 
myConnection.Close(); 
} 
catch (SqlException SQLexc) 
{ 
Response.Write(SQLexc.ToString ()); 
} 
Response.End(); 

} 
} 
}