File upload (multi-file upload)/download

Usually we will be involved in uploading files and downloading files, before the STRUTS2 framework, we are using Apache under the Commons sub-project FileUpload components to upload files, but in that case, the code looks cumbersome, and not flexible, After learning Struts2, struts2 for file upload download provides a better implementation mechanism, here I separately on the file download and multi-file upload source code to do a bit of talk

File Upload

First create a JSP page (for multiple file uploads)

<%@ page language= "Java"Import= "java.util.*" pageencoding= "UTF-8"%><%String Path=Request.getcontextpath (); String BasePath= Request.getscheme () + "://" + request.getservername () + ":" +Request.getserverport ()+ path + "/";%><%@ taglib uri= "/struts-tags" prefix= "s"%><! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" >
Success.jsp page (used to display the file and file type after the upload was successful)
Import= "java.util.*" pageencoding= "UTF-8"%><%    = request.getcontextpath ();     = Request.getscheme () + "://"            + request.getservername () + ":" + Request.getserverport (            )+ path + "/"  ; %><%@ taglib uri= "/struts-tags" prefix= "s"%><! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" >    file you uploaded is:<s:property value= "Uploadfilename"/><br/>     file type:<s:property value= "Uploadcontenttype"/></body >
Next create the Uploadaction class
 Packagecn.happy.action;ImportJava.io.File;ImportJava.io.FileInputStream;ImportJava.io.FileOutputStream;ImportOrg.apache.struts2.ServletActionContext;ImportCom.opensymphony.xwork2.ActionContext;ImportCom.opensymphony.xwork2.ActionSupport; Public classUploadactionextendsActionsupport {//properties for uploading files    Privatefile[] upload; //types of uploaded files    Privatestring[] Uploadcontenttype; //name of the uploaded file    Privatestring[] Uploadfilename; //the address of the uploaded file    PrivateString Savepath; @Override PublicString Execute ()throwsException {byte[] buffer=New byte[1024];  for(inti = 0; i < upload.length; i++) {                        //create an input stream to upload filesFileInputStream fis=NewFileInputStream (Getupload () [i]); //build the output stream of the uploaded file, getimagefilename () [i]FileOutputStream fos=NewFileOutputStream (Getsavepath () + "\ \" +getuploadfilename () [i]); intLength=fis.read (buffer);  while(length>0) {fos.write (buffer,0, length); Length=fis.read (buffer);            } fis.close ();            Fos.flush ();        Fos.close (); }        returnSUCCESS; }                 PublicString Getsavepath () {returnServletactioncontext.getservletcontext (). Getrealpath (Savepath); }     Public voidSetsavepath (String savepath) { This. Savepath =Savepath; }         Publicfile[] Getupload () {returnupload; }     Public voidsetupload (file[] upload) { This. Upload =upload; }     Publicstring[] Getuploadcontenttype () {returnUploadcontenttype; }     Public voidSetuploadcontenttype (string[] uploadcontenttype) { This. Uploadcontenttype =Uploadcontenttype; }     Publicstring[] Getuploadfilename () {returnUploadfilename; }     Public voidsetuploadfilename (string[] uploadfilename) { This. Uploadfilename =Uploadfilename; }                    }
Finally write the configuration file Struts.xml
<?xml version= "1.0" encoding= "UTF-8"? ><! DOCTYPE struts    Public " -//apache software foundation//dtd Struts Configuration 2.3//en "    http://struts.apache.org/dtds/struts-2.3.dtd" ><struts>    <!--dynamic method call--     <constant name= "Struts.devmode" value= "false"/>            <  Package extends= "Struts-default" >                class= "Cn.happy.action.UploadAction" method= "execute" >            <param name= "Savepath" >/image</param>           <result name= "Success" >/upload/success.jsp </result>        </action>    </Package ></struts>
Achieve effect display
After selecting a file
File download
Writing JSP pages
Import= "java.util.*" pageencoding= "Utf-8"%><%== request.getscheme () + "://" + Request.getservername () + ":" +request.getserverport () +path+ "/"; %><! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" >
Creating the Filedownaction Class
 PackageAction;ImportJava.io.BufferedInputStream;ImportJava.io.FileInputStream;Importjava.io.FileNotFoundException;Importjava.io.IOException;ImportJava.io.InputStream;ImportOrg.apache.struts2.ServletActionContext;ImportCom.opensymphony.xwork2.ActionSupport; Public classFiledownactionextendsActionsupport {//read the directory of downloaded files    PrivateString InputPath; //Download the file name    PrivateString FileName; //read the input stream of the downloaded file    PrivateInputStream InputStream; //types of download files    PrivateString Conetnttype; //Create InputStream input stream     PublicInputStream getInputStream ()throwsIOException {System.out.println ("123"); String Path=Servletactioncontext.getservletcontext (). Getrealpath (InputPath); return NewBufferedinputstream (NewFileInputStream (path+ "\ \" +FileName)); } @Override PublicString Execute ()throwsexception{returnSUCCESS; }             PublicString Getinputpath () {returnInputPath; }     PublicString GetFileName () {returnFileName; }     PublicString Getconetnttype () {returnConetnttype; }     Public voidSetinputpath (String inputpath) { This. InputPath =InputPath; }     Public voidsetfilename (String fileName) {filename=FileName; }     Public voidSetinputstream (InputStream inputstream) { This. InputStream =InputStream; }     Public voidSetconetnttype (String conetnttype) { This. Conetnttype =Conetnttype; }}
Writing a configuration file Struts.xml
<?xml version= "1.0" encoding= "UTF-8"? ><!DOCTYPE Struts public"-//apache software foundation//dtd Struts Configuration 2.3//en" "Http://struts.apache.org/dtds/struts-2.3.dtd" > <struts> <constant name= "Struts.devmode" value= "true" ></constant> < PackageName= "Default" namespace= "/"extends= "Struts-default" > <action name= "Download"class= "action. Filedownaction "> <param name=" InputPath ">/image</param> <result name=" succ                ESS "type=" stream "> <param name=" ContentType ">application/octet-stream</param> <param name= "InputName" >inputStream</param> <param name= "Contentdisposition" >attachment ; Filename= "${filename}" </param> <param name= "buffersize" >4096</param> </ Result> </action> </ Package> </struts>
Finally, create an image file in the Webroot directory to save the downloaded files
Achieve results
Click File Download
Additional
Importing JAR Packages
Web. XML configuration
<?xml version= "1.0" encoding= "UTF-8"? ><web-app version= "2.5"xmlns= "Http://java.sun.com/xml/ns/javaee"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "Http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd "><display-name></display-name> <filter> <filter-name>struts2</filter-name> < filter-class>org.apache.struts2.dispatcher.ng.filter.strutsprepareandexecutefilter</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <welcome-file-list> <welcome-file>index.jsp</we Lcome-file> </welcome-file-list></web-app>
File upload (multi-file upload)/download