本文将介绍如何利用JSP，实现基于WEB的数据库图片存储和显示的方法。在传统的JSP方法中，无法存储动态的显示图片，利用数据库我们就能做到这点
数据库应用程序，特别是根据WEB的数据库应用程序，常会涉及到图片信息的存储和显现 。
一般咱们运用的办法是将所要显现的图片存在特定的目录下，在数据库中保存相应的图片 的称号，在JSP中树立相应的数据源，运用数据库拜访技能处理图片信息。可是，假如咱们想 动态的显现图片，上述办法就不能满足需求了。咱们有必要把图片存入数据库，然后经过编程动 态地显现咱们需求的图片。实际操作中，能够运用JSP的编程形式来完成图片的数据库存储和 显现。
树立后台数据库
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向数据库存储二进制图片
发动Dreamweaver MX后，新建一个JSP文件。其代码如下所示。
<%@ 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"> 标题<input name="picname" type="text"> 图片<input name="pic" type="file"> <input type="Submit" name="button1" value="提交"> </form> </body></html>
将此文件保存为InputImage.JSP文件，雁足传书testimage.jsp文件是用来将图片数据存入数据 库的，详细代码如下所示：
<%@ 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");//树立 Statement光辉String picname=request.getParameter("picname");String pic=request.getParameter("pic");//取得所要显现图片的标题、存储途径、内容，并进行中 文编码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();//将数据存入数据库out.println("Success,You Have Insert an Image Successfully");%></body></html>
网页中动态显现图片
接下来咱们要编程从数据库中取出图片，其代码如下所示。
<%@ 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(); // 图片输出的输出流 InputStream in = rs.getBinaryStream(1); byte b[] = new byte[0x7a120]; for(int i = in.read(b); i != -1;) { sout.write(b); //将缓冲区的输入 输出到页面 in.read(b); } sout.flush (); //输入结束，铲除缓冲 sout.close(); } %> </body></html>
将此文件保存为testimageout.jsp文件。下一步要做的作业便是运用HTML符号：
<%@ 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"> <% } rs.close(); %></body></html>
【修改引荐】
- 在 JDBC规划中责怪JSP拜访数据库
- 比照 JSP和ASP.NET的存储进程
- 怎么 从JSP页面传送动态图片
