1. Introduction
Database applications, especially WEB-based database applications, usually involve the storage and display of image information.
The common method is to store the image to be displayed in a specific directory, store the name of the image in the database, and create the corresponding data source in JSP, use Database Access technology to process image information. However, if we want to dynamically display images, the above method cannot meet our needs. We must store images in the database and dynamically display the images we need through programming. In practice, the JSP programming mode can be used to store and display image databases.
2. Create a background database
if exists (select * from dbo.sysobjects
where id =
object_id(N'[dbo].[p]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop
table [dbo].[p]
GO
CREATE TABLE [dbo].[p] (
[picid] [int] IDENTITY
(1, 1) NOT NULL ,
[picname] [varchar] (50) COLLATE Chinese_PRC_CI_AS NULL
,
[pic] [image] NULL
) ON [PRIMARY] TEXTIMAGE_ON
[PRIMARY]
GO |
3. store binary images to the database
Start Dreamweaver MX and create a new JSP file. The Code is as follows.
<% @ Page
ContentType = "text/html; charset = gb2312" %>
<%
String path =
Request. getContextPath ();
String basePath =
Request. getScheme () + ": //" + request. getServerName ()
+ ":" + Request. getServerPort () + path + "/";
%>
<! DOCTYPE
Html public "-// W3C // dtd html 4.01
Transitional // EN ">
<Html>
<Head>
<Base
Href = "<% = basePath %>">
<Title> My JSP 'inputimage. jsp'
Starting page </title>
<Meta http-equiv = "pragma"
Content = "no-cache">
<Meta http-equiv = "cache-control"
Content = "no-cache">
<Meta http-equiv = "expires"
Content = "0">
<Meta http-equiv = "keywords"
Content = "keyword1, keyword2, keyword3">
<Meta
Http-equiv = "description" content = "This is my page">
<! --
<Link rel = "stylesheet" type = "text/css" href = "styles.css">
-->
</Head>
<Body>
<Form action = "testimage. jsp"
Method = "Post"> <br>
Question <input name = "picname"
Type = "text"> <br>
Image <input name = "pic"
Type = "file"> <br>
<Input type = "Submit" name = "button1"
Value = "Submit"> <br>
</Form>
</Body>
</Html> |
Save this file as an InputImage. jsp file. The testimage. jsp file is used to store image data to the database. The specific code is as follows:
<% @ Page contenttype = "text/html; charset = gb2312" %>
<% @ Page
Import = "Java. SQL. *" %>
<% @ Page import = "Java. util. *" %>
<% @
Page import = "Java. Text. *" %>
<% @ Page
Import = "Java. Io. *" %>
<JSP: usebean id = "conn" Scope = "page"
Class = "dbconn. dbresult"/>
<%
String Path =
Request. getcontextpath ();
String basepath =
Request. getscheme () + ": //" + request. getservername () +
":" + Request. getserverport () + path + "/";
%>
<! Doctype
HTML public "-// W3C // dtd html 4.01
Transitional // en ">
<HTML>
<Head>
<Base
Href = "<% = basepath %>">
<Title> my JSP 'testimage. jsp 'starting
Page </title>
<Meta http-equiv = "Pragma"
Content = "no-Cache">
<Meta http-equiv = "cache-control"
Content = "no-Cache">
<Meta http-equiv = "expires"
Content = "0">
<Meta http-equiv = "keywords"
Content = "keyword1, keyword2, keyword3">
<Meta
HTTP-equiv = "Description" content = "this is my page">
<! --
<LINK rel = "stylesheet" type = "text/CSS" href = "styles.css">
-->
</Head>
<Body>
<%
Request. setcharacterencoding ("gb2312 ");
// Create a statement object
String
Picname = request. getparameter ("picname ");
String
PIC = request. getparameter ("pic ");
// Obtain the title, storage path, and content of the image to be displayed, and encode it in Chinese.
Fileinputstream
STR = new fileinputstream (PIC );
String SQL = "insert into P (picname, PIC)
Values (?,?) ";
Preparedstatement
Pstmt = conn. getpreparedstatement (SQL );
Pstmt. setstring (1, picname );
Pstmt. setbinarystream (2, STR, str. Available ());
Pstmt.exe cute ();
// Store data into the database
Out. println ("Success, You
Have Insert an Image
Successfully ");
%>
</Body>
</Html> |
4. dynamically display images on the webpage
Next, we will program to retrieve images from the database. The Code is as follows.
<% @ Page contentType = "text/html; charset = gb2312" %>
<% @ Page
Import = "java. SQL. *" %>
<% @ Page import = "java. util. *" %>
<% @
Page import = "java. text. *" %>
<% @ Page
Import = "java. io. *" %>
<Jsp: useBean id = "conn" scope = "page"
Class = "dbconn. DBResult"/>
<%
String path =
Request. getContextPath ();
String basePath =
Request. getScheme () + ": //" + request. getServerName () +
":" + Request. getServerPort () + path + "/";
%>
<! DOCTYPE
Html public "-// W3C // dtd html 4.01
Transitional // EN ">
<Html>
<Head>
<Base
Href = "<% = basePath %>">
<Title> My JSP 'testimageout. jput'
Starting page </title>
<Meta http-equiv = "pragma"
Content = "no-cache">
<Meta http-equiv = "cache-control"
Content = "no-cache">
<Meta http-equiv = "expires"
Content = "0">
<Meta http-equiv = "keywords"
Content = "keyword1, keyword2, keyword3">
<Meta
Http-equiv = "description" content = "This is my page">
<! --
<Link rel = "stylesheet" type = "text/css" href = "styles.css">
-->
</Head>
<Body>
<%
Int id =
Integer. parseint (request. getparameter ("picid "));
String SQL = "select PIC
From P where picid = "+ ID;
Resultset rs = conn. getresult (SQL );
While (Rs. Next ())
{
Servletoutputstream sout =
Response. getoutputstream ();
// Output stream of image output
Inputstream in =
Rs. getbinarystream (1 );
Byte B [] = new byte [0x7a120];
For (int
I = in. Read (B); I! =
-1 ;)
{
Sout. Write (B );
// Output the buffer input to the page
In. Read (B );
}
Sout. Flush ();
// After the input is complete, clear the buffer.
Sout. Close ();
}
%>
</Body>
</Html> |
Save this file as a testimageout. jsp file. The next step is to use HTML tags:
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page
import="java.sql.*" %>
<%@ page import="java.util.*"%>
<%@
page import="java.text.*"%>
<%@ page
import="java.io.*"%>
<jsp:useBean id="conn" scope="page"
class="dbconn.DBResult"/>
<%
String path =
request.getContextPath();
String basePath =
request.getScheme()+"://"+request.getServerName()+
":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE
HTML PUBLIC "-//W3C//DTD HTML 4.01
Transitional//EN">
<base
href="<%=basePath%>">
<title>My JSP 'lookpic.jsp' starting
page</title>
<meta http-equiv="pragma"
content="no-cache">
<meta http-equiv="cache-control"
content="no-cache">
<meta http-equiv="expires"
content="0">
<meta http-equiv="keywords"
content="keyword1,keyword2,keyword3">
<meta
http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<body>
<%
String sql = "select *
from p";
ResultSet rs=conn.getResult(sql);
while(rs.next())
{
%>
<ccid_file values="testimageout" % />" width="100"
height="100">
<br>
<%
}
rs.close();
%>
</body>
|
