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用Servlvet实现文件上传
// file upload module
// It cannot handle nested data (multipart content withinmultipart content)
// or internationalized content (such as non Latin-1 filenames).

//
// Designed by Mouse King, Last modified on August 2nd,2000
// file upload example
// one file control can upload a file once
// you can customize the file size,now it is 5m
// the ftp server target path is /usr/local/jakarta-tomcat/bin。

package BBS;

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class UploadTest extends HttpServlet {
String rootPath, successMessage;

static final int MAX_SIZE = 102400;
public void init(ServletConfig config) throws ServletException
{
super.init(config);
}

public void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException
{
response.setContentType("text/html");
PrintWriter out = new PrintWriter (response.getOutputStream());
out.println("<html>");
out.println("<head><title>Servlet1</title></head>");
out.println("<body><form ENCTYPE="multipart/form-data" method=post action=‘‘><input type=file enctype="multipart/form-data" name=filedata>");
out.println("<input type=submit></form>");
out.println("</body></html>");
out.close();
}


public void doPost(HttpServletRequest request,HttpServletResponse response)
{
ServletOutputStream out=null;
DataInputStream in=null;
FileOutputStream fileOut=null;
try
{
/*set content type of response and get handle to output stream in case we are unable to redirect client*/
response.setContentType("text/plain");
out = response.getOutputStream();
}
catch (IOException e)
{
//print error message to standard out
System.out.println("Error getting output stream.");
System.out.println("Error description: " + e);
return;
}

try
{
String contentType = request.getContentType();
//make sure content type is multipart/form-data
if(contentType != null && contentType.indexOf("multipart/form-data") != -1)
{
//open input stream from client to capture upload file
in = new DataInputStream(request.getInputStream());
//get length of content data
int formDataLength = request.getContentLength();
//allocate a byte array to store content data
byte dataBytes[] = new byte[formDataLength];
//read file into byte array
int bytesRead = 0;
int totalBytesRead = 0;
int sizeCheck = 0;
while (totalBytesRead < formDataLength)
{
//check for maximum file size violation
sizeCheck = totalBytesRead + in.available();
if (sizeCheck > MAX_SIZE)
{
out.println("Sorry, file is too large to upload.");
return;
}
bytesRead = in.read(dataBytes, totalBytesRead, formDataLength);
totalBytesRead += bytesRead;
}
//create string from byte array for easy manipulation
String file = new String(dataBytes);
//since byte array is stored in string, release memory
dataBytes = null;
/*get boundary value (boundary is a unique string that
separates content data)*/
int lastIndex = contentType.lastIndexOf("=");
String boundary = contentType.substring(lastIndex+1,
contentType.length());
//get Directory web variable from request
String directory="";
if (file.indexOf("name="Directory"") > 0)
{
directory = file.substring(file.indexOf("name="Directory""));
//remove carriage return
directory = directory.substring(directory.indexOf(" ")+1);
//remove carriage return
directory = directory.substring(directory.indexOf(" ")+1);
//get Directory
directory = directory.substring(0,directory.indexOf(" ")-1);
/*make sure user didn‘t select a directory higher in the directory tree*/
if (directory.indexOf("..") > 0)
{
out.println("Security Error: You can‘t upload " +"to a directory higher in the directory tree.");
return;
}
}
//get SuccessPage web variable from request
String successPage="";
if (file.indexOf("name="SuccessPage"") > 0)
{
successPage = file.substring(file.indexOf("name="SuccessPage""));
//remove carriage return
successPage = successPage.substring(successPage.indexOf(" ")+1);
//remove carriage return
successPage = successPage.substring(successPage.indexOf(" ")+1);
//get success page
successPage = successPage.substring(0,successPage.indexOf(" ")-1);}
//get OverWrite flag web variable from request
String overWrite;
if (file.indexOf("name="OverWrite"") > 0)
{
overWrite = file.substring(file.indexOf("name="OverWrite""));
//remove carriage return
overWrite = overWrite.substring(
overWrite.indexOf(" ")+1);
//remove carriage return
overWrite = overWrite.substring(overWrite.indexOf(" ")+1);
overWrite = overWrite.substring(0,overWrite.indexOf(" ")-1);
}
else
{
overWrite = "false";
}
//get OverWritePage web variable from request
String overWritePage="";
if (file.indexOf("name="OverWritePage"") > 0)
{
overWritePage = file.substring(file.indexOf("name="OverWritePage""));
//remove carriage return
overWritePage = overWritePage.substring(overWritePage.indexOf(" ")+1);
//remove carriage return
overWritePage = overWritePage.substring(overWritePage.indexOf(" ")+1);
//get overwrite page
overWritePage = overWritePage.substring(0,overWritePage.indexOf(" ")-1);
}
//get filename of upload file
String saveFile = file.substring(file.indexOf("filename="")+10);
saveFile = saveFile.substring(0,saveFile.indexOf(" "));
saveFile = saveFile.substring(saveFile.lastIndexOf("\")+1,
saveFile.indexOf("""));
/*remove boundary markers and other multipart/form-data
tags from beginning of upload file section*/
int pos; //position in upload file
//find position of upload file section of request
pos = file.indexOf("filename="");
//find position of content-disposition line
pos = file.indexOf(" ",pos)+1;
//find position of content-type line
pos = file.indexOf(" ",pos)+1;
//find position of blank line
pos = file.indexOf(" ",pos)+1;
/*find the location of the next boundary marker
(marking the end of the upload file data)*/
int boundaryLocation = file.indexOf(boundary,pos)-4;
//upload file lies between pos and boundaryLocation
file = file.substring(pos,boundaryLocation);
//build the full path of the upload file
String fileName = new String(rootPath + directory +
saveFile);
//create File object to check for existence of file
File checkFile = new File(fileName);
if (checkFile.exists())
{
/*file exists, if OverWrite flag is off, give
message and abort*/
if (!overWrite.toLowerCase().equals("true"))
{
if (overWritePage.equals(""))
{
/*OverWrite HTML page URL not received, respond
with generic message*/
out.println("Sorry, file already exists.");
}
else
{
//redirect client to OverWrite HTML page
response.sendRedirect(overWritePage);
}
return;
}
}
/*create File object to check for existence of
Directory*/
File fileDir = new File(rootPath + directory);
if (!fileDir.exists())
{
//Directory doesn‘t exist, create it
fileDir.mkdirs();
}
//instantiate file output stream
fileOut = new FileOutputStream(fileName);
//write the string to the file as a byte array
fileOut.write(file.getBytes(),0,file.length());
if (successPage.equals(""))
{
/*success HTML page URL not received, respond with
eneric success message*/
out.println(successMessage);
out.println("File written to: " + fileName);
}
else
{
//redirect client to success HTML page
response.sendRedirect(successPage);
}
}
else //request is not multipart/form-data
{
//send error message to client
out.println("Request not multipart/form-data.");
}
}
catch(Exception e)
{
try
{
//print error message to standard out
System.out.println("Error in doPost: " + e);
//send error message to client
out.println("An unexpected error has occurred.");
out.println("Error description: " + e);
}
catch (Exception f) {}
}
finally
{
try
{
fileOut.close(); //close file output stream
}
catch (Exception f) {}
try
{
in.close(); //close input stream from client
}
catch (Exception f) {}
try
{
out.close(); //close output stream to client
}
catch (Exception f) {}
}
}

}
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