学过文件上传下载之后，简单的来体会一下所学知识。
jsp展示
1.upload.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
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>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>
This is my JSP page. <br>
<form action="uploadServlet" method="post" enctype="multipart/form-data">
<p>请选择文件<input type="file" name="file"></p>
<p><input type="submit" value="提交"/></p>
</form>
</body>
</html>
对于上传文件的处理
2.uploadServlet
package servlet;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class UploadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//实例化磁盘文件解析工厂
DiskFileItemFactory dfif = new DiskFileItemFactory();
//实例化解析对象
ServletFileUpload sfu = new ServletFileUpload(dfif);
String filename =null;
InputStream is=null;
FileOutputStream fos=null;
//解析请求信息
try {
List<FileItem> list = sfu.parseRequest(request);
//找到form中上传的文件
for(FileItem fi : list){
if(!fi.isFormField()){
is = fi.getInputStream();
//截取文件名，放入指定的文件目录下
filename = fi.getName();
filename = filename.substring(filename.lastIndexOf("\\")+1);
fos = new FileOutputStream("D:\\javajava\\upload\\"+filename);//个人设定的所要下载的文件目录
//写入到指定文件
byte[] b = new byte[512];
int i;
while((i=is.read(b))!=-1){
fos.write(b);
}
//将文件名保存到数据库
insert(filename);
}
}
List namelist = getFileName();
request.getSession().setAttribute("namelist", namelist);
request.getRequestDispatcher("jsp/download.jsp").forward(request, response);
} catch (FileUploadException e) {
e.printStackTrace();
}finally{
fos.close();
is.close();
}
}
//将文件名称存储到数据库
public boolean insert(String str){
try{
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mytest?useUnicode=true&characterEncoding=utf-8","root","root");
PreparedStatement ps = conn.prepareStatement("insert into filename(name) values(?) ");
ps.setString(1, str);
int n=0;
if((n=ps.executeUpdate())>0){
return true;
}
ps.close();
conn.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return false;
}
@SuppressWarnings("null")
//从数据库中得到所有上传的文件名称
public List getFileName(){
List list=new ArrayList();
try {
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mytest?useUnicode=true&characterEncoding=utf-8","root","root");
PreparedStatement ps = conn.prepareStatement("select * from filename");
ResultSet rs = ps.executeQuery();
while(rs.next()){
String str=rs.getString(2);
list.add(str);
}
rs.close();
ps.close();
conn.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return list;
}
}
3.下载页面的jsp展示
download.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
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>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>
<font size="10" >您可以下载以下文件：</font>
<%
List list = (List)session.getAttribute("namelist");
String str=null;
for(int i=0;i<list.size();i++){
str = (String)list.get(i);
%>
<a href="downloadServlet?filename=<%=str %>"> <%=str %></a>
<%} %>
</body>
</html>
4.文件下载的后端处理
package servlet;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DownloadServlet extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.print("here");
request.setCharacterEncoding("utf-8");
String filename = request.getParameter("filename");
response.setContentType("multipart/form-data");
response.setHeader("Content-Disposition", "attachment;filename="+filename);
FileInputStream fis = new FileInputStream("D:\\javajava\\upload\\"+filename);
ServletOutputStream sos = response.getOutputStream();
byte[] b = new byte[512];
int i;
while((i=fis.read(b))!=-1){
sos.write(b);
}
fis.close();
sos.close();
}
}
