如何在Web页上实现文件上传_学习爱好者 Cfan.Net.Cn


首页电脑学院黑客教程网站技术网页特效免费论文公文写作演讲发言实用文档职场指南时尚生活情感男女其他资讯

您的位置：首页-> 网站技术-> JSP技术-> 如何在Web页上实现文件上传

如何在Web页上实现文件上传

public class UploadServlet extends HttpServlet 
{ 
  //default maximum allowable file size is 100k 
  static final int MAX_SIZE = 102400; 
  //instance variables to store root and success message 
  String rootPath, successMessage; 
  /** 
   * init method is called when servlet is initialized. 
   */ 
  public void init(ServletConfig config) throws ServletException 
  { 
    super.init(config); 
    //get path in which to save file 
    rootPath = config.getInitParameter("RootPath"); 
    if (rootPath == null) 
    { 
      rootPath = "/"; 
    } 
    /*Get message to show when upload is complete. Used only if 
      a success redirect page is not supplied.*/ 
    successMessage = config.getInitParameter("SuccessMessage"); 
    if (successMessage == null) 
    { 
      successMessage = "File upload complete!"; 
    } 
  } 
  /** 
   * doPost reads the uploaded data from the request and writes 
   * it to a file. 
   */ 
  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 
    { 
      //get content type of client request 
      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); 
          //get overwrite flag 
          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 
            generic 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) {} 
    } 
  } 
} 
 
 

在百度中查找更多如何在Web页上实现文件上传的内容

职场宝典	职场故事职场跳槽职场文化职场理财职场充电情感天地职场女性职场礼仪职场新人
报告总结	述职报告工作总结调查报告工作汇报计划方案个人总结社会实践规章制度调研报告实习报告考察报告辞职报告
演讲发言	竞职演说就职演说精彩演说爱国演讲英语演讲十七大演讲安全生产演讲稿
节日祝福	重阳节国庆节教师节中秋节情人节七夕节劳动节妇女节清明节愚人节春节元旦圣诞节儿童节端午节母亲节新婚祝福生日祝福
讲话致辞	开业开幕会议主持庆典致辞会议发言党风廉政党政报告贺电慰问婚丧嫁娶思想宣传
法律常识	基本常识法律文书权益常识劳动保障婚姻继承民事诉讼刑事诉讼
党建材料	入党申请思想学习党性分析思想汇报转正申请民主生活党委党建入团申请申报材料
求职简历	个人简历求职自荐求职谋略面试技巧求职英语自我鉴定英文简历简历封面
心得体会	心得体会经验交流读后感
时政热点	和谐社会先进性教育新农村建设十七大八荣八耻科学发展观劳动合同法
人际沟通	社交技巧社交礼仪口才技巧谈话技巧演讲技巧
营销技巧	电话销售网络销售推销技巧促销技巧销售口才营销手段销售技巧谈判技巧

“ 如何在Web页上实现文件上传”来源于网络，版权归作者所有！勿用于商业用途。

JSP技术

ASP技术
 PHP技术
 JSP技术
 .NET技术
 服务器技术
 数据库开发
 其它类

本类阅读TOP10

·Struts实践入门（原创）
·tomcat配置手册（server.xml）——中文版
·MySQL的JDBC驱动程序下载地址
·一个log4j的学习笔计
·DOM文档操作和XML文件互相转换的java实现 (转贴)
·JAVA几个常见错误简析
·HttpServletRequest, ServletRequest, request
·JBOSS中，中文问题的彻底解决
·JSP传递参数方法
·ORACLE ORA-00600错误的阐述

→ 广告

关于本站｜服务条款｜广告服务｜客服中心｜发布文章｜网站留言