在TCP/IP中，最早出现的文件上传机制是FTP.它将文件由客户端到服务器的标准机制。
但是在JSP中不能使用FTP来上传文件，这是有JSP的运行机制所决定的。
通过为表单元素设置Method="post" enctype="multipart/form-data" 属性，让表单提交的数据以二进制编码的方式提交，在接受此请求的servlet中的二进制流来获取内容，就可以取得上传文件的内容，从而实现文件的上传。
代码分两部分
part1:前台页面index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<html>
<head>
</head>
<body>
<form action="UploadFile" method="post" enctype="multipart/form-data">
<table>
<tr>
<td align="center">
请选择上传的文件:<input type="file" name="fileName"/> <input type="submit" value="上传"/>${result} </td>
</tr>
</table>
</form>
</body>
</html>
part2:servlet代码
package com.file;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.RandomAccessFile;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class UploadFile extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//写入缓存文件
InputStream fileSource=request.getInputStream();
String tempFileName="E:/tempFile";
File tempFile=new File(tempFileName);
FileOutputStream outputStram=new FileOutputStream(tempFile);
byte[] b=new byte[1024];
int n;
while((n=fileSource.read(b))!=-1){
outputStram.write(b,0,n);
}
outputStram.close();
fileSource.close();
System.out.println("成功");
//获取文件名
RandomAccessFile randomFile=new RandomAccessFile(tempFile,"r");
randomFile.readLine();
String str=randomFile.readLine();
int beginIndex=str.lastIndexOf("\\")+1;
int endIndex=str.lastIndexOf("\"");
String filename=str.substring(beginIndex, endIndex);
System.out.println("filename:"+filename);
//获取上传文件内容的开始位置
randomFile.seek(0);
long startPosition=0;
int i=1;
while((n=randomFile.readByte())!=-1&&i<=4){
if(n==‘\n‘){
startPosition=randomFile.getFilePointer();
i++;
}
}
startPosition=startPosition-1;
//获取上传文件内容的结束位置 randomFile.seek(randomFile.length());
long endPosition=randomFile.getFilePointer();
int j=1;
while(endPosition>=0&&j<=2){
endPosition--;
randomFile.seek(endPosition);
if(randomFile.readByte()==‘\n‘){
j++;
}
}
endPosition=endPosition-1;
//上传文件
String path=getServletContext().getRealPath("/")+"MyImages"; //指定上传文件的目录 File fileupload=new File(path);
if(!fileupload.exists()){
fileupload.mkdir();
}
File saveFile=new File(path,filename);
RandomAccessFile RAF=new RandomAccessFile(saveFile,"rw");
randomFile.seek(startPosition);
while(startPosition<endPosition){
RAF.write(randomFile.readByte());
startPosition=randomFile.getFilePointer();
}
RAF.close();
randomFile.close();
tempFile.delete();
request.setAttribute("result","上传成功!");
RequestDispatcher dispatcher=request.getRequestDispatcher("index.jsp");
dispatcher.forward(request,response);
}
}
时间： 2024-08-28 19:44:58