我是JSP和servlet的新手。请帮我解决我的问题。我已经完成了将多个文件上传到MySQL数据库的代码，并且成功。我有一个jsp页面（“ filelist.jsp”），其中包含所有用户上传的文件。因此，我想在jsp中使用更多过滤器选项来Search特定文件。我也尝试使用过滤，现在它已部分完成。我有一个（“ Search.jsp”）页面，其中将显示用户搜索的数据。我的代码中也有“ Download”列，以便用户可以下载该文件。 但是问题是我无法从search.jsp页面下载特定文件。我正在使用netbeans8，tomcat 8。
这是我的filelist.jsp页面
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Statement"%>
<%@page import="com.servlet.db.DB"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%
%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link href="bootstrap.css" rel="stylesheet" type="text/css">
<title>file_list Page</title>
<style>
tr,td,th{
padding: 20px;
text-align: center;
}
.container {
position:"absolute";
padding: 16px 0px;
top:0;
right:0;
display: flex;
justify-content: space-between;
align-items: center;
}
form.form-inline{
float: right;
}
#ddl{
width:150px;
}
#ddl2{
width:150px;
}
#cat{
width:175px;
}
</style>
</head>
<body>
<!-- <form action="" method="POST">
<div class="container">
<div class="form-group">
<div class="input-group">
<input type="text" name="search" class="form-control" placeholder="Search here..." autocomplete="off"/>
<button type="submit" value="Search" class="btn btn-primary">Search</button>
</div>
</div>
</div>
</form> -->
<h3>Search here..</h3>
<form action="logout.jsp" align="right">
<input type="submit" value="Logout"/>
</form>
<form name="empForm" action="search.jsp" method="post">
<div>
<table border="1" colspan="2">
<thead>
<tr>
<th style="alignment-adjust: auto">Z ID:</th>
<td><input type="text" name="zid" value="" /></td>
</tr>
<tr>
<th>First Name :</th>
<td><input type="text" name="firstname" value="" /></td>
</tr>
<tr>
<th>Last Name:</th>
<td><input type="text" name="lastname" value=""/></td>
</tr>
<tr style="display:none">
<th>Division:</th>
<td><input type="text" name="division" value=""/></td>
</tr>
<tr style="display:none">
<th>Reporting Unit:</th>
<td><input type="text" name="reportingunit" value=""/></td>
</tr>
<tr style="display:none">
<th>Document No.</th>
<td><input type="text" name="documentnumber" value=""/></td>
</tr>
<tr style="display:none">
<th>Document Name:</th>
<td><input type="text" name="documentname" value=""/></td>
</tr>
<tr style="display:none">
<th>Document Uploader:</th>
<td><input type="text" name="documentuploader" value=""/></td>
</tr>
<tr style="display:none">
<th>Document Owner:</th>
<td><input type="text" name="documentowner" value=""/></td>
</tr>
<tr>
<th>Document Type</th>
<td>
<select name="documenttype">
<option value=""></option>
<option value="Agreement">Agreement</option>
<option value="Contract">Contract</option>
<option value="PO">PO</option>
<option value="Invoice">Invoice</option>
<option value="COA">COA</option>
<option value="Lease Deed">Lease Deed</option>
<option value="AMC">AMC</option>
<option value="Direct Material">Direct Material</option>
<option value="Indirect Material/Services">Indirect Material/Services</option>
</select>
</td>
</tr>
<tr>
<th>Document Category</th>
<td>
<select name="documentcategory" id="cat">
<option value=""></option>
<option value="Customer">Customer</option>
<option value="Vendor">Vendor</option>
<option value="Internal">Internal</option>
</select>
</td>
</tr>
<tr style="display:none">
<th>By Function:</th>
<td><input type="text" name="byfunction" value=""/></td>
</tr>
<tr style="display:none">
<th>Creator:</th>
<td><input type="text" name="creator" value=""/></td>
</tr>
<tr style="display:none">
<th>Modifier:</th>
<td><input type="text" name="modifier" value=""/></td>
</tr>
<tr style="display:none">
<th>Approver:.</th>
<td><input type="text" name="approver" value=""/></td>
</tr>
<tr style="display:none">
<th>Mail Id:</th>
<td><input type="text" name="mailid" value=""/></td>
</tr>
<tr style="display:none">
<th>Added Date:</th>
<td><input type="text" name="added_date" value=""/></td>
</tr>
<tr style="display:none">
<th>Download:</th>
<td><input type="text" name="download" value=""/></td>
</tr>
<tr>
<td colspan="3" >
<center> <input type="submit" value="Get File(s)" /></center>
</td>
</tr>
</thead>
</table>
</div>
</form>
<br><br>
<center>
<table border="2">
<tr>
<th style="width: 20%">ID</th>
<th style="width: 20%">First Name</th>
<th style="width: 20%">Last Name</th>
<th style="width: 20%">File Name</th>
<th style="width: 20%">File Path</th>
<th style="width: 20%">division</th>
<th style="width: 20%">Reporting Unit</th>
<th style="width: 20%">Document No.</th>
<th style="width: 20%">Document Name</th>
<th style="width: 20%">Document Uploader</th>
<th style="width: 20%">Document Owner</th>
<th style="width: 20%">Document Type</th>
<th style="width: 20%">Document Category</th>
<th style="width: 20%">By Function</th>
<th style="width: 20%">Creator</th>
<th style="width: 20%">Modifier</th>
<th style="width: 20%">Approver</th>
<th style="width: 20%">Z ID</th>
<th style="width: 20%">Mail ID</th>
<th style="width: 20%">Added Date</th>
<th style="width: 20%">Download</th>
</tr>
<%
Connection con = null;
PreparedStatement ps = null;
ResultSet rs = null;
%>
<%
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/newfieldsadded","root","");
String sql = "select * from newfiles";
ps = con.prepareStatement(sql);
Statement stmt = con.createStatement();
String query = request.getParameter("search");
String data;
if(query != null){
data = "select * from newfiles where id like'%"+query+"%' or firstname like'%"+query+"%' or lastname like'%"+query+"%' or filename like'%"+query+"%' or division like'%"+query+"%' or reportingunit like'%"+query+"%' or documentnumber like'%"+query+"%' or documentname like'%"+query+"%' or documentuploader like'%"+query+"%' or documentowner like'%"+query+"%' or documenttype like'%"+query+"%' or documentcategory like'%"+query+"%' or byfunction like'%"+query+"%' or creator like'%"+query+"%' or modifier like'%"+query+"%' or approver like'%"+query+"%' or zid like'%"+query+"%' or mailid like'%"+query+"%'";
}
else{
data = "select * from newfiles order by 1 asc";
}
rs = stmt.executeQuery(data);
while(rs.next()){
%>
<tr>
<td><%=rs.getInt("id")%></td>
<td><%=rs.getString("firstname")%></td>
<td><%=rs.getString("lastname")%></td>
<td><%=rs.getString("filename")%></td>
<td><%=rs.getString("path")%></td>
<td><%=rs.getString("division")%></td>
<td><%=rs.getString("reportingunit")%></td>
<td><%=rs.getString("documentnumber")%></td>
<td><%=rs.getString("documentname")%></td>
<td><%=rs.getString("documentuploader")%></td>
<td><%=rs.getString("documentowner")%></td>
<td><%=rs.getString("documenttype")%></td>
<td><%=rs.getString("documentcategory")%></td>
<td><%=rs.getString("byfunction")%></td>
<td><%=rs.getString("creator")%></td>
<td><%=rs.getString("modifier")%></td>
<td><%=rs.getString("approver")%></td>
<td><%=rs.getString("zid")%></td>
<td><%=rs.getString("mailid")%></td>
<td><%=rs.getTimestamp("added_date")%></td>
<td><a href="DownloadServletClass?fileName=<%=rs.getString(4)%>">Download</a></td>
</tr>
<%
}
%>
</table><br>
<a href="index.jsp">Home</a>
</center>
</body>
</html>这是我的Search.jsp页面
<%@ page import="java.io.*,java.util.*,java.sql.*"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql"%>
<%@ page isELIgnored="false"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<sql:setDataSource var="emp" driver="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost:3306/newfieldsadded" user="root" password="" />
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Search Page</title>
</head>
<body>
<h1>Searched Data</h1>
<form name="empForm" action="index.jsp" method="post">
<div>
<table border="2" style="width:100%">
<tr>
<th style="width:70%">Z ID</th>
<th style="width:70%">First Name</th>
<th>Last Name</th>
<th>Division</th>
<th>Reporting Unit</th>
<th>Document No.</th>
<th>Document Name</th>
<th>Document Uploader</th>
<th>Document Owner</th>
<th>Document Type</th>
<th>Document Category</th>
<th>By Function</th>
<th>Creator</th>
<th>Modifier</th>
<th>Approver</th>
<th>Mail Id</th>
<th>Added date</th>
<th>Download</th>
</tr>
<tbody>
<%
// out.println("select * from newfiles emp where emp.zid like '%"+request.getParameter("zid")+"%' and "
// + " emp.firstname like '%"+request.getParameter("firstname")+"%' and" + " emp.lastname like '%"+request.getParameter("lastname")+"%' and" + " emp.documenttype like '%"+request.getParameter("documenttype")+"%' and"
// + " emp.documentcategory like '%"+request.getParameter("documentcategory")+"%' ");
//out.println("select count(*) from newfiles");
%>
<sql:query var="empData" dataSource="${emp}">
select * from newfiles emp where emp.zid like '%
<%=request.getParameter("zid")%>%' and emp.firstname like '%
<%=request.getParameter("firstname")%>%' and emp.lastname like '%
<%=request.getParameter("lastname")%>%' and emp.division like '%
<%=request.getParameter("division")%>%' and emp.reportingunit like '%
<%=request.getParameter("reportingunit")%>%' and emp.documentnumber like '%
<%=request.getParameter("documentnumber")%>%' and emp.documentname like '%
<%=request.getParameter("documentname")%>%' and emp.documentuploader like '%
<%=request.getParameter("documentuploader")%>%' and emp.documentowner like '%
<%=request.getParameter("documentowner")%>%' and emp.documenttype like '%
<%=request.getParameter("documenttype")%>%' and emp.documentcategory like '%
<%=request.getParameter("documentcategory")%>%' and emp.byfunction like '%
<%=request.getParameter("byfunction")%>%' and emp.creator like '%
<%=request.getParameter("creator")%>%' and emp.modifier like '%
<%=request.getParameter("modifier")%>%' and emp.approver like '%
<%=request.getParameter("approver")%>%' and emp.mailid like '%
<%=request.getParameter("mailid")%>%' and emp.added_date like '%
<%=request.getParameter("added_date")%>%'
</sql:query>
<c:forEach var="row" items="${empData.rows}">
<tr>
<td>
<c:out value="${row.zid}" />
</td>
<td>
<c:out value="${row.firstname}" />
</td>
<td>
<c:out value="${row.lastname}" />
</td>
<td>
<c:out value="${row.division}" />
</td>
<td>
<c:out value="${row.reportingunit}" />
</td>
<td>
<c:out value="${row.documentnumber}" />
</td>
<td>
<c:out value="${row.documentname}" />
</td>
<td>
<c:out value="${row.documentuploader}" />
</td>
<td>
<c:out value="${row.documentowner}" />
</td>
<td>
<c:out value="${row.documenttype}" />
</td>
<td>
<c:out value="${row.documentcategory}" />
</td>
<td>
<c:out value="${row.byfunction}" />
</td>
<td>
<c:out value="${row.creator}" />
</td>
<td>
<c:out value="${row.modifier}" />
</td>
<td>
<c:out value="${row.approver}" />
</td>
<td>
<c:out value="${row.mailid}" />
</td>
<td>
<c:out value="${row.added_date}" />
</td>
<td><a href="DownloadServletClass?fileName=<%=request.getParameter(" filename ") %>">Download</a></td>
</tr>
</c:forEach>
</tbody>
</table>
</div>
</form>
<br>
<center> <a href="index.jsp">Home</a></center>
</body>
</html>首先，我不会将数据库代码与.jsp代码混合使用。阅读有关jstl的信息，并尝试将其分开。其次，如果您发布了错误（如果有的话），那就太好了。 DownloadServletClass的代码在哪里？当您单击下载时会发生什么？
我有一个小示例，它使用称为testservlet的servlet下载文件。 .jsp端：
<form action="testservlet" method="GET">
<input type="text" placeholder="filename" name="filename" />
<input type="submit" value="Download file" />
</form>
这里是servlet部分：
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String filename = req.getParameter("filename");
resp.setContentType("APPLICATION/OCTET-STREAM");
resp.setHeader("Content-Disposition", "attachment;filename=\""+filename+"\"");
try(FileInputStream fileInputStream = new FileInputStream("C:/Users/user/Documents/"+filename+"")){
int i;
PrintWriter out = resp.getWriter();
while((i=fileInputStream.read()) != -1) {
out.write(i);
}
}catch(Exception e) {
e.printStackTrace();
}
}
运行此文件，我可以从我的文档文件夹中下载在文本字段中键入name.extension的任何文件。