servlet implementation file Upload, multiple file Upload example _javascript tips

One, the servlet implementation file upload, need to add a third party provided jar package

Download Address:

1) Commons-fileupload-1.2.2-bin.zip: Click to open the link

2) Commons-io-2.3-bin.zip: Click to open the link

Then put the two jar packages under the Lib folder:

Second: File Upload form submission method must be post way,

Encoding type: enctype= "Multipart/form-data", default is application/x-www-form-urlencoded

Like what:

<form action= "FileUpload" enctype= "Multipart/form-data" method= "POST" >

Third, for example:

1.fileupload.jsp

<%@ page language= "java" import= "javautil*" pageencoding= "UTF-8"%> <% String Path = Requestgetcontextpath (); 
String basepath = requestgetscheme () + "://" +requestgetservername () + ":" +requestgetserverport () +path+ "/"; %> <! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML transitional//en" >  

2. Actual processing of file upload Fileupload.java

Package comservletfileupload; 
Import Javaiofile; 
Import javaio*; 
Import javaioioexception; 
Import Javaioprintwriter;  
Import javautillist; 
Import javaxservletservletexception; 
Import Javaxservlethttphttpservlet; 
Import Javaxservlethttphttpservletrequest; 
Import Javaxservlethttphttpservletresponse; 
Import Orgapachecommonsfileuploadfileitem; 
Import orgapachecommonsfileuploadfileuploadexception; 
Import Orgapachecommonsfileuploaddiskdiskfileitemfactory; 
 
Import Orgapachecommonsfileuploadservletservletfileupload; /** * * @author Administrator * File Upload * Specific steps: * 1 obtain Disk File entry Factory Diskfileitemfactory to guide package * 2) Use request to obtain the true path for Temporary file storage, and final file storage, these two storage locations can be different, or the same * 3 set some properties on the Diskfileitemfactory object * 4) High level API file upload processing servletfileupload upload = new 
 Servletfileupload (Factory); 
 * The purpose is to invoke the Parserequest (request) method to obtain the Fileitem collection list, * * 5) to obtain the information in the Fileitem object, to traverse, to determine whether the information submitted by the form is ordinary text information and to handle it. * 6) * The first itemwrite (new File (Path,filename) provided by a third party);  Write directly to disk *The second manual processing * */public class FileUpload extends HttpServlet {public void DoPost (HttpServletRequest request, Http Servletresponse response) throws Servletexception, IOException {requestsetcharacterencoding ("utf-8"); 
    /Set code//Get Disk File entry Factory Diskfileitemfactory factory = new Diskfileitemfactory (); 
     
    Gets the path to which the file needs to be uploaded String Path = Requestgetrealpath ("/upload"); If you do not have the following two lines, upload large files will occupy a lot of memory,//set up storage room temporarily, this storage room, can and final storage file directory different/** * Principle it is to save to the temporary storage room, and then in the real write to the corresponding directory of hard On the disk, * in fact, when uploading a file, is actually uploaded two copies, the first is in the TEM format * and then it is actually written to the corresponding directory of the hard disk/factorysetrepository (new file (PA 
    th)); 
     
    Set the size of the cache, when the upload file capacity exceeds the cache, directly to the temporary storage Room factorysetsizethreshold (1024*1024); 
     
     
    High-level API file upload processing servletfileupload upload = new Servletfileupload (factory); 
       
      try {//can upload multiple files list<fileitem> List = (list<fileitem>) uploadparserequest (request); For (Fileitem iteM:list) {//Get the form's property name String name = Itemgetfieldname (); If the obtained form information is a plain text message if (Itemisformfield ()) {//Gets the user-specific input string, the name is very good because the form submits a character 
           
          String value = Itemgetstring () of serial type; 
        Requestsetattribute (name, value); 
           ///To process incoming, not simple strings, such as binary pictures, movies these else {/** * below three steps, mainly get the name of the uploaded file 
          *//Get path name String value = Itemgetname (); 
          Index to the last backslash int start = Valuelastindexof ("\"); 
           
          Intercept the string name of the uploaded file, plus 1 to remove the backslash, string filename = valuesubstring (start+1); 
           
          Requestsetattribute (name, filename); 
           
          The exception that is actually written to disk//It throws is caught with exception//itemwrite (new File (Path,filename)); Manual Write OutputStream out = new FileOutputStream (new File (Path,filename)); 
           
          InputStream in = Itemgetinputstream (); 
          int length = 0; 
           
          byte [] buf = new byte[1024]; 
 
          Systemoutprintln ("Get the total volume of uploaded files:" +itemgetsize ());  Inread (BUF) each read data is stored in the BUF array while ((length = Inread (BUF))!=-1) {//in BUF array 
             
          Remove data to write to (output stream) on disk Outwrite (buf, 0, length); 
          } inclose (); 
        Outclose (); 
      catch (Fileuploadexception e) {//TODO auto-generated catch block 
    Eprintstacktrace (); 
    catch (Exception e) {//TODO auto-generated catch block//eprintstacktrace (); 
     
 
  } requestgetrequestdispatcher ("filedemojsp") forward (request, response); 
 } System.out.println ("Gets the total volume of uploaded files:" +item.getsize ());

3.filedemo.jsp

<%@ page language= "java" import= "javautil*" pageencoding= "UTF-8"%> <% String Path = Requestgetcontextpath (); 
String basepath = requestgetscheme () + "://" +requestgetservername () + ":" +requestgetserverport () +path+ "/"; %> <! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML transitional//en" >  

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