我尝试使用此分页代码从 mysql 数据库中获取图像（blob 类型），并显示在我的 jsp 页面上。我想让它像 Yotube 之类的网站一样发生，当用户搜索视频文件时，用户可以以分页方式查看缩略图格式的视频列表。我想做这样的事情。为此，我尝试了以下代码，但仅显示数据库中的一张图像。
<%@page import="java.io.InputStream"%>
<%@page import="java.io.OutputStream"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@page import="java.util.*,xugglerPack.bean"%>
<%@page import="java.sql.*"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<%
String myfile = session.getAttribute("myfile").toString();
%>
<html lang="en-US" xmlns="http://www.w3.org/1999/xhtml" dir="ltr">
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
</head>
<body>
<div>
<div>
<ul>
<li>
<%String user = (String) session.getAttribute("thisuser");%>
<%=user%>
</li>
<li>
<div>
<a href="logout.jsp"> Logout </a>
</div>
</li>
</ul>
</div>
<div> </div>
</div>
<div>
<%!
public int nullIntconvert(String str) {
int num = 0;
if (str == null) {
str = "0";
} else if ((str.trim()).equals("null")) {
str = "0";
} else if (str.equals("")) {
str = "0";
}
try {
num = Integer.parseInt(str);
} catch (Exception e) {
}
return num;
}
%>
<%
Blob image = null;
byte[] imgData = null;
Statement stmt = null;
ResultSet rs = null;
Connection conn = null;
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn =
DriverManager.getConnection("jdbc:mysql://localhost:3306/lakhya","root",
"pass");
ResultSet rs1 = null;
ResultSet rs2 = null;
PreparedStatement ps1 = null;
PreparedStatement ps2 = null;
int showRows = 2;
int totalRecords = 10;
int totalRows = nullIntconvert(request.getParameter("totalRows"));
int totalPages =
nullIntconvert(request.getParameter("totalPages"));
int iPageNo = nullIntconvert(request.getParameter("iPageNo"));
int cPageNo = nullIntconvert(request.getParameter("cPageNo"));
int startResult = 0;
int endResult = 0;
if (iPageNo == 0) {
iPageNo = 0;
} else {
iPageNo = Math.abs((iPageNo - 1) * showRows);
}
String query1 = "SELECT SQL_CALC_FOUND_ROWS thumbnail FROM files
where fname like '%" + myfile + "%' limit " + iPageNo + "," + showRows + "";
ps1 = conn.prepareStatement(query1);
rs1 = ps1.executeQuery();
String query2 = "SELECT FOUND_ROWS() as cnt";
ps2 = conn.prepareStatement(query2);
rs2 = ps2.executeQuery();
if (rs2.next()) {
totalRows = rs2.getInt("cnt");
}
if (totalRows == 0) {
%>
<table style="margin-left:450px">
<tr>
<td><b><font color="whitesmoke">No Results..</font> </b></td>
</tr>
</table>
<% } else {
%>
<form>
<input type="hidden" name="iPageNo" value="<%=iPageNo%>"/>
<input type="hidden" name="cPageNo" value="<%=cPageNo%>"/>
<input type="hidden" name="showRows" value="<%=showRows%>"/>
<table style="margin-left:450px;margin-top: 15px;"width="50%"
cellpadding="0" cellspacing="0">
<%
String imgLen = "";
if (rs1.next()) {
imgLen =
rs1.getString("thumbnail");
System.out.println("the image
length is" + imgLen.length());
}
String query11 = "SELECT thumbnail FROM
files where fname like '%" + myfile + "%'";
ps1 = conn.prepareStatement(query11);
rs1 = ps1.executeQuery();
while (rs1.next()) {
int len = imgLen.length();
byte[] rb = new byte[len];
InputStream readImg =
rs1.getBinaryStream(1);
int index = readImg.read(rb, 0, len);
System.out.println("the index is " +
index);
//stmt.close();
response.reset();
response.setContentType("image/jpg");
%>
<tr>
<td style="padding-bottom:2em">
<% response.getOutputStream().write(rb, 0, len);
response.getOutputStream().flush();
%>
</td>
</tr>
<%
}
}
%>
<%
try {
if (totalRows < (iPageNo + showRows)) {
endResult = totalRows;
} else {
endResult = (iPageNo + showRows);
}
startResult = (iPageNo + 1);
totalPages = ((int) (Math.ceil((double) totalRows /
showRows)));
} catch (Exception e) {
e.printStackTrace();
}
%>
</table>
<br/>
<table style="margin-left:450px">
<tr>
<td colspan="1">
<div>
<%
int i = 0;
int cPage = 0;
if (totalRows != 0) {
cPage = ((int) (Math.ceil((double)
endResult / (totalRecords * showRows))));
int prePageNo = (cPage * totalRecords) -
((totalRecords - 1) + totalRecords);
if ((cPage * totalRecords) - (totalRecords)
> 0) {
%>
<a href="add2list.jsp?iPageNo=<%=prePageNo%>&cPageNo=
<%=prePageNo%>"> << Previous</a>
<%
}
for (i = ((cPage * totalRecords) - (totalRecords - 1));
i <= (cPage * totalRecords); i++)
{
if (i == ((iPageNo / showRows) + 1))
{%>
<a href="add2list.jsp?iPageNo=<%=i%>"
style="cursor:pointer;color: red"><b><%=i%></b></a>
<%
} else if (i <= totalPages) {
%>
<a href="add2list.jsp?iPageNo=<%=i%>"><%=i%></a>
<%
}
}
if
(totalPages > totalRecords && i < totalPages) {
%>
<a href="add2list.jsp?iPageNo=<%=i%>&cPageNo=<%=i%>"> >>
Next</a>
<%
}
}
%>
<font color="whitesmoke"><b>Rows <%=startResult%> -
<%=endResult%> Total Rows <%=totalRows%> </b></font>
</div>
</td>
</tr>
</table>
</form>
<%
try {
if (ps1 != null) {
ps1.close();
}
if (rs1 != null) {
rs1.close();
}
if (ps2 != null) {
ps2.close();
}
if (rs2 != null) {
rs2.close();
}
if (conn != null) {
conn.close();
}
} catch (Exception e) {
e.printStackTrace();
}
%>
</div>
</body>
</html>