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    oracle数据库基本语句 [用JSP实现数据库图片的存储与显示实例]

    时间:2018-08-15 16:34:46 来源:精彩博文网 本文已影响 精彩博文网手机站

    1. 引言

    数据库应用程序,特别是基于WEB的数据库应用程序,常会涉及到图片信息的存储和显示。

    通常我们使用的方法是将所要显示的图片存在特定的目录下,在数据库中保存相应的图片的名称,在JSP中建立相应的数据源,利用数据库访问技术处理图片信息。但是,如果我们想动态的显示图片,上述方法就不能满足需要了。我们必须把图片存入数据库,然后通过编程动态地显示我们需要的图片。实际操作中,可以利用JSP的编程模式来实现图片的数据库存储和显示。

    2. 建立后台数据库

    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.向数据库存储二进制图片

    启动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"><br>
    题目<input name="picname" type="text"><br>
    图片<input name="pic" type="file"><br>
    <input type="Submit" name="button1" value="提交"><br>
    </form>
    </body>
    </html>

    将此文件保存为InputImage.jsp文件,其中testimage.jsp文件是用来将图片数据存入数据库的,具体代码如下所示:

    <%@ 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");
    //建立Statement对象
    String picname=request.getParameter("picname");
    String pic=request.getParameter("pic");
    //获得所要显示图片的标题、存储路径、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>

    4. 网页中动态显示图片

    接下来我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();
    //输入完毕,清除缓冲
    sout.close();
    }
    %>
    </body>
    </html>

    将此文件保存为testimageout.jsp文件。下一步要做的工作就是使用HTML标记:

    <%@ 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>

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