用Servlvet实现文件上传

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// 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(""); out.println(""); out.println("

"); out.println("

"); out.println(" "); 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) {} } } } 下载本文示例代码


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