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用Servlvet实现文件上传的功能

王朝java/jsp·作者佚名  2006-01-08
窄屏简体版  字體: |||超大  

// 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("\n")+1);

//remove carriage return

directory = directory.substring(directory.indexOf("\n")+1);

//get Directory

directory = directory.substring(0,directory.indexOf("\n")-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("\n")+1);

//remove carriage return

successPage = successPage.substring(successPage.indexOf("\n")+1);

//get success page

successPage = successPage.substring(0,successPage.indexOf("\n")-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("\n")+1);

//remove carriage return

overWrite = overWrite.substring(overWrite.indexOf("\n")+1);

overWrite = overWrite.substring(0,overWrite.indexOf("\n")-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("\n")+1);

//remove carriage return

overWritePage = overWritePage.substring(overWritePage.indexOf("\n")+1);

//get overwrite page

overWritePage = overWritePage.substring(0,overWritePage.indexOf("\n")-1);

}

//get filename of upload file

String saveFile = file.substring(file.indexOf("filename=\"")+10);

saveFile = saveFile.substring(0,saveFile.indexOf("\n"));

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("\n",pos)+1;

//find position of content-type line

pos = file.indexOf("\n",pos)+1;

//find position of blank line

pos = file.indexOf("\n",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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