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<?xml version='1.0' encoding='GB2312'?>
<?xml-stylesheet type='text/xsl' href='../csdn.xsl'?>
<Topic>
<Issue>
<PostUserNickName></PostUserNickName>
<rank>一级(初级)</rank>
<ranknum>user1</ranknum>
<credit>140</credit>
<TopicId>534699</TopicId>
<TopicName>如何实现文件上传</TopicName>
<PostUserId>164255</PostUserId>
<PostUserName>yuri</PostUserName>
<RoomName>JSP</RoomName>
<ReplyNum>2</ReplyNum>
<PostDateTime>2002-2-20 20:14:24</PostDateTime>
<Point>100</Point>
<ReadNum>0</ReadNum>
<RoomId>28</RoomId>
<EndState>2</EndState>
<Content>如何在Web页上实现文件上传</Content>
</Issue>
<Replys>
<Reply>
<PostUserNickName></PostUserNickName>
<rank>五级(中级)</rank>
<ranknum>user5</ranknum>
<credit>100</credit>
<ReplyID>3586827</ReplyID>
<TopicID>534699</TopicID>
<PostUserId>98264</PostUserId>
<PostUserName>mfc42d</PostUserName>
<Point>100</Point>
<Content>give&#32;you&#32;a&#32;example&#32;split&#32;two&#32;parts
public&#32;class&#32;UploadServlet&#32;extends&#32;HttpServlet&#32;
{&#32;
 //default&#32;maximum&#32;allowable&#32;file&#32;size&#32;is&#32;100k&#32;
 static&#32;final&#32;int&#32;MAX_SIZE&#32;=&#32;102400;&#32;
 //instance&#32;variables&#32;to&#32;store&#32;root&#32;and&#32;success&#32;message&#32;
 String&#32;rootPath,&#32;successMessage;&#32;
 /**&#32;
 &#32;*&#32;init&#32;method&#32;is&#32;called&#32;when&#32;servlet&#32;is&#32;initialized.&#32;
 &#32;*/&#32;
 public&#32;void&#32;init(ServletConfig&#32;config)&#32;throws&#32;ServletException&#32;
 {&#32;
  super.init(config);&#32;
  //get&#32;path&#32;in&#32;which&#32;to&#32;save&#32;file&#32;
  rootPath&#32;=&#32;config.getInitParameter("RootPath");&#32;
  if&#32;(rootPath&#32;==&#32;null)&#32;
  {&#32;
   rootPath&#32;=&#32;"/";&#32;
  }&#32;
  /*Get&#32;message&#32;to&#32;show&#32;when&#32;upload&#32;is&#32;complete.&#32;Used&#32;only&#32;if&#32;
   a&#32;success&#32;redirect&#32;page&#32;is&#32;not&#32;supplied.*/&#32;
  successMessage&#32;=&#32;config.getInitParameter("SuccessMessage");&#32;
  if&#32;(successMessage&#32;==&#32;null)&#32;
  {&#32;
   successMessage&#32;=&#32;"File&#32;upload&#32;complete!";&#32;
  }&#32;
 }&#32;
 /**&#32;
 &#32;*&#32;doPost&#32;reads&#32;the&#32;uploaded&#32;data&#32;from&#32;the&#32;request&#32;and&#32;writes&#32;
 &#32;*&#32;it&#32;to&#32;a&#32;file.&#32;
 &#32;*/&#32;
 public&#32;void&#32;doPost(HttpServletRequest&#32;request,&#32;
  HttpServletResponse&#32;response)&#32;
 {&#32;
  ServletOutputStream&#32;out=null;&#32;
  DataInputStream&#32;in=null;&#32;
  FileOutputStream&#32;fileOut=null;&#32;
  try&#32;
  {&#32;
   /*set&#32;content&#32;type&#32;of&#32;response&#32;and&#32;get&#32;handle&#32;to&#32;output&#32;
    stream&#32;in&#32;case&#32;we&#32;are&#32;unable&#32;to&#32;redirect&#32;client*/&#32;
   response.setContentType("text/plain");&#32;
   out&#32;=&#32;response.getOutputStream();&#32;
  }&#32;
  catch&#32;(IOException&#32;e)&#32;
  {&#32;
   //print&#32;error&#32;message&#32;to&#32;standard&#32;out&#32;
   System.out.println("Error&#32;getting&#32;output&#32;stream.");&#32;
   System.out.println("Error&#32;description:&#32;"&#32;+&#32;e);&#32;
   return;&#32;
  }&#32;
  try&#32;
  {&#32;
   //get&#32;content&#32;type&#32;of&#32;client&#32;request&#32;
   String&#32;contentType&#32;=&#32;request.getContentType();&#32;
   //make&#32;sure&#32;content&#32;type&#32;is&#32;multipart/form-data&#32;
   if(contentType&#32;!=&#32;null&#32;&amp;&amp;&#32;contentType.indexOf(&#32;
    "multipart/form-data")&#32;!=&#32;-1)&#32;
   {&#32;
    //open&#32;input&#32;stream&#32;from&#32;client&#32;to&#32;capture&#32;upload&#32;file&#32;
    in&#32;=&#32;new&#32;DataInputStream(request.getInputStream());&#32;
    //get&#32;length&#32;of&#32;content&#32;data&#32;
    int&#32;formDataLength&#32;=&#32;request.getContentLength();&#32;
    //allocate&#32;a&#32;byte&#32;array&#32;to&#32;store&#32;content&#32;data&#32;
    byte&#32;dataBytes[]&#32;=&#32;new&#32;byte[formDataLength];&#32;
    //read&#32;file&#32;into&#32;byte&#32;array&#32;
    int&#32;bytesRead&#32;=&#32;0;&#32;
    int&#32;totalBytesRead&#32;=&#32;0;&#32;
    int&#32;sizeCheck&#32;=&#32;0;&#32;
    while&#32;(totalBytesRead&#32;&lt;&#32;formDataLength)&#32;
    {&#32;
     //check&#32;for&#32;maximum&#32;file&#32;size&#32;violation&#32;
     sizeCheck&#32;=&#32;totalBytesRead&#32;+&#32;in.available();&#32;
     if&#32;(sizeCheck&#32;&gt;&#32;MAX_SIZE)&#32;
     {&#32;
      out.println("Sorry,&#32;file&#32;is&#32;too&#32;large&#32;to&#32;upload.");&#32;
      return;&#32;
     }&#32;
     bytesRead&#32;=&#32;in.read(dataBytes,&#32;totalBytesRead,&#32;
      formDataLength);&#32;
     totalBytesRead&#32;+=&#32;bytesRead;&#32;
    }&#32;
    //create&#32;string&#32;from&#32;byte&#32;array&#32;for&#32;easy&#32;manipulation&#32;
    String&#32;file&#32;=&#32;new&#32;String(dataBytes);&#32;
    //since&#32;byte&#32;array&#32;is&#32;stored&#32;in&#32;string,&#32;release&#32;memory&#32;
    dataBytes&#32;=&#32;null;&#32;
    /*get&#32;boundary&#32;value&#32;(boundary&#32;is&#32;a&#32;unique&#32;string&#32;that&#32;
     separates&#32;content&#32;data)*/&#32;
    int&#32;lastIndex&#32;=&#32;contentType.lastIndexOf("=");&#32;
    String&#32;boundary&#32;=&#32;contentType.substring(lastIndex+1,&#32;
     contentType.length());&#32;
    //get&#32;Directory&#32;web&#32;variable&#32;from&#32;request&#32;
    String&#32;directory="";&#32;
    if&#32;(file.indexOf("name=\"Directory\"")&#32;&gt;&#32;0)&#32;
    {&#32;
     directory&#32;=&#32;file.substring(&#32;
      file.indexOf("name=\"Directory\""));&#32;
     //remove&#32;carriage&#32;return&#32;
     directory&#32;=&#32;directory.substring(&#32;
      directory.indexOf("\n")+1);&#32;
     //remove&#32;carriage&#32;return&#32;
     directory&#32;=&#32;directory.substring(&#32;
      directory.indexOf("\n")+1);&#32;
</Content>
<PostDateTime>2002-2-20 20:17:34</PostDateTime>
</Reply>
<Reply>
<PostUserNickName></PostUserNickName>
<rank>五级(中级)</rank>
<ranknum>user5</ranknum>
<credit>100</credit>
<ReplyID>3586833</ReplyID>
<TopicID>534699</TopicID>
<PostUserId>98264</PostUserId>
<PostUserName>mfc42d</PostUserName>
<Point>0</Point>
<Content>//get&#32;Directory&#32;
     directory&#32;=&#32;directory.substring(0,&#32;
      directory.indexOf("\n")-1);&#32;
     /*make&#32;sure&#32;user&#32;didn't&#32;select&#32;a&#32;directory&#32;higher&#32;in&#32;
      the&#32;directory&#32;tree*/&#32;
     if&#32;(directory.indexOf("..")&#32;&gt;&#32;0)&#32;
     {&#32;
      out.println("Security&#32;Error:&#32;You&#32;can't&#32;upload&#32;"&#32;+&#32;
       "to&#32;a&#32;directory&#32;higher&#32;in&#32;the&#32;directory&#32;tree.");&#32;
      return;&#32;
     }&#32;
    }&#32;
    //get&#32;SuccessPage&#32;web&#32;variable&#32;from&#32;request&#32;
    String&#32;successPage="";&#32;
    if&#32;(file.indexOf("name=\"SuccessPage\"")&#32;&gt;&#32;0)&#32;
    {&#32;
     successPage&#32;=&#32;file.substring(&#32;

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