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用JSP實現(xiàn)數(shù)據(jù)庫圖片的存儲與顯示
1. 序言
數(shù)據(jù)庫應(yīng)用程序，特別是基于WEB的數(shù)據(jù)庫應(yīng)用程序，常會涉及到圖片信息的存儲和顯示。
通常我們使用的方法是將所要顯示的圖片存在特定的目錄下，在數(shù)據(jù)庫中保存相應(yīng)的圖片的名稱，在JSP中建立相應(yīng)的數(shù)據(jù)源，利用數(shù)據(jù)庫訪問技術(shù)處理圖片信息。但是，如果我們想動態(tài)的顯示圖片，上述方法就不能滿足需要了。我們必須把圖片存入數(shù)據(jù)庫，然后通過編程動態(tài)地顯示我們需要的圖片。實際操作中，可以利用JSP的編程模式來實現(xiàn)圖片的數(shù)據(jù)庫存儲和顯示。
2. 建立后臺數(shù)據(jù)庫
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.向數(shù)據(jù)庫存儲二進制圖片
啟動Dreamweaver MX后，新建一個JSP文件。其代碼如下所示。
﹤%@ 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﹥ 題目﹤input name="picname" type="text"﹥﹤br﹥ 圖片﹤input name="pic" type="file"﹥﹤br﹥ ﹤input type="Submit" name="button1" value="提交"﹥﹤br﹥ ﹤/form﹥ ﹤/body﹥ ﹤/html﹥ |
將此文件保存為InputImage.jsp文件，其中testimage.jsp文件是用來將圖片數(shù)據(jù)存入數(shù)據(jù)庫的，具體代碼如下所示：
﹤%@ 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");
//建立Statement對象
String picname=request.getParameter("picname");
String pic=request.getParameter("pic");
//獲得所要顯示圖片的標題、存儲路徑、內(nèi)容，并進行中文編碼
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.execute();
//將數(shù)據(jù)存入數(shù)據(jù)庫
out.println("Success,You Have Insert an Image Successfully");
%﹥
﹤/body﹥
﹤/html﹥
|
4. 網(wǎng)頁中動態(tài)顯示圖片
接下來我們要編程從數(shù)據(jù)庫中取出圖片，其代碼如下所示。
﹤%@ 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.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﹥
﹤%
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();
//圖片輸出的輸出流
InputStream in = rs.getBinaryStream(1);
byte b[] = new byte[0x7a120];
for(int i = in.read(b); i != -1;)
{
sout.write(b);
//將緩沖區(qū)的輸入輸出到頁面
in.read(b);
}
sout.flush();
//輸入完畢，清除緩沖
sout.close();
}
%﹥
﹤/body﹥
﹤/html﹥
|
將此文件保存為testimageout.jsp文件。下一步要做的工作就是使用HTML標記：
﹤%@ 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 '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"﹥
--﹥
﹤/head﹥
﹤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﹥
﹤/html﹥
|
網(wǎng)頁題目：用JSP實現(xiàn)數(shù)據(jù)庫圖片的存儲與顯示
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