Java using commos-fileupload to implement file upload and download instance resolution _java

First of all to introduce a file upload

Entity classes

Import Java.sql.Timestamp; /** * * * @Decription File Upload entity class */public class Upfile {private string id;//ID primary key uses UUID to randomly generate private string uuidname ; UUID name private string filename;//file name private string Savepath; Save path private Timestamp uploadtime; Upload time private string description;//file to describe private strings username; 
User name Public upfile () {super (); Public upfile (string ID, string uuidname, String filename, string savepath, Timestamp uploadtime, string description, 
String username) {super (); 
This.id = ID; 
This.uuidname = Uuidname; 
This.filename = filename; 
This.savepath = Savepath; 
This.uploadtime = Uploadtime; 
this.description = description; 
This.username = Username; 
Public String GetDescription () {return description; 
Public String GetFileName () {return filename; 
Public String GetId () {return id; 
Public String Getsavepath () {return savepath; 
Public Timestamp Getuploadtime () {return uploadtime; Public String GetUserName () {
return username; 
Public String Getuuidname () {return uuidname; 
} public void SetDescription (String description) {this.description = description; 
public void Setfilename (String filename) {this.filename = filename; 
public void SetId (String id) {this.id = ID; 
} public void Setsavepath (String savepath) {this.savepath = Savepath; 
public void Setuploadtime (Timestamp uploadtime) {this.uploadtime = Uploadtime; 
} public void Setusername (String username) {this.username = username; 
} public void Setuuidname (String uuidname) {this.uuidname = Uuidname;  } 
}

Page

<%@ page language= "java" import= "java.util.*" pageencoding= "UTF-8"%> <% String Path = Request.getcontextpath () 
; 
String basepath = request.getscheme () + "://" +request.getservername () + ":" +request.getserverport () +path+ "/"; %> <! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" >  

Servlet

Import java.io.IOException; 
Import javax.servlet.ServletException; 
Import Javax.servlet.http.HttpServlet; 
Import Javax.servlet.http.HttpServletRequest; 
Import Javax.servlet.http.HttpServletResponse; 
Import org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException; 
Import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException; 
Import Org.apache.commons.fileupload.servlet.ServletFileUpload; 
Import Com.itheima.domain.Upfile; 
Import com.itheima.exception.MyException; 
Import Com.itheima.service.UpfileService; 
Import Com.itheima.service.impl.UpfileServiceImpl; 
Import Com.itheima.untils.WebUntil; public class Uploadfileservlet extends HttpServlet {public void doget (HttpServletRequest request, HttpServletResponse re 
Sponse) throws Servletexception, IOException {doPost (request, response); public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {/ /Judgment form is not composed of multiple parts if (! ServletfileuPload.ismultipartcontent (Request) {Request.setattribute ("msg", "Table single setting error, check the Enctype property is set correctly"); 
Request.getrequestdispatcher ("/upload.jsp"). Forward (request, response); 
return; 
//is a multiple-part acquisition and traversal returns a file Upload object containing all uploaded information try {upfile upfile=webuntil.upload (request); 
Upfileservice upfileservice=new Upfileserviceimpl (); 
Boolean flag=upfileservice.add (Upfile); 
if (flag) {Request.setattribute ("msg", "Upload successful"); 
Request.getrequestdispatcher ("/upload.jsp"). Forward (request, response); 
return; 
}else{Request.setattribute ("msg", "Upload failed, please try again"); 
Request.getrequestdispatcher ("/upload.jsp"). Forward (request, response); 
return; 
}}catch (Filesizelimitexceededexception e) {e.printstacktrace (); 
Request.setattribute ("MSG", "Single file size, exceeding maximum limit"); 
Request.getrequestdispatcher ("/upload.jsp"). Forward (request, response); 
return; 
catch (Sizelimitexceededexception e) {e.printstacktrace (); 
Request.setattribute ("MSG", "Total file size, exceeding maximum limit"); Request.getrequestdispatcher ("/upload.jsp"). Forward (Request, response); 
return; } 
} 
}

Tool Class

Import Java.io.File; 
Import java.io.FileNotFoundException; 
Import Java.io.FileOutputStream; 
Import java.io.IOException; 
Import Java.io.InputStream; 
Import Java.io.OutputStream; 
Import java.io.UnsupportedEncodingException; 
Import java.util.ArrayList; 
Import java.util.List; 
Import Java.util.UUID; 
Import Javax.servlet.http.HttpServletRequest; 
Import Org.apache.commons.fileupload.FileItem; 
Import Org.apache.commons.fileupload.FileUploadBase; 
Import org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException; 
Import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException; 
Import org.apache.commons.fileupload.FileUploadException; 
Import Org.apache.commons.fileupload.ProgressListener; 
Import Org.apache.commons.fileupload.disk.DiskFileItemFactory; 
Import Org.apache.commons.fileupload.servlet.ServletFileUpload; 
Import Com.itheima.domain.Upfile; 
Import com.itheima.exception.MyException; /** * File Upload Tool class * @Decription TODO */public classWebuntil {/** * File Upload method * @param request requests Parameter incoming * @return returns a Upfile object * @throws filesizelimitexceededexception * Throws Sizelimitexceededexception * @throws IOException * * public static upfile upload (HttpServletRequest request) thro 
WS Filesizelimitexceededexception, sizelimitexceededexception {upfile upfile=new upfile (); 
Arraylist<string> filelist=initlist (); 
try {//Get Disk File Object factory diskfileitemfactory factory=new diskfileitemfactory (); 
String tmp=request.getsession (). Getservletcontext (). Getrealpath ("/tmp"); 
SYSTEM.OUT.PRINTLN (TMP); 
Initial chemical Plant setfactory (factory,tmp); 
Get File Upload parser servletfileupload upload=new servletfileupload (Factory); 
Initialization parser setupload (upload); 
Get file List collection List<fileitem> list = upload.parserequest (request); Traversal for (Fileitem items:list) {//judge is not a normal table single object if (Items.isformfield ()) {//Get the name String of the uploaded form Fieldname=items.getf 
Ieldname (); 
Value String fieldvalue=items.getstring ("UTF-8"); To determine if ("username". Equals (FieldName)) {//Setting Upfile.setusername (Fieldvalue); 
}else if ("description". Equals (FieldName)) {//Set properties Upfile.setdescription (Fieldvalue); 
}else{//Is the file ready to upload//get filename String filename=items.getname (); 
Handle the difference in filename obtained because of browser differences int index=filename.lastindexof ("\"); 
if (index!=-1) {filename=filename.substring (index+1); 
//Generate random filename String uuidname=generatefilename (filename); 
Gets the uploaded file path String savepath=request.getsession (). Getservletcontext (). Getrealpath ("/web-inf/upload"); 
Gets the input stream in the request object InputStream in = Items.getinputstream (); 
The files are scattered and stored in different paths to find the path Savepath=generaterandomdir (savepath,uuidname); 
Copy file UploadFile (in,savepath,uuidname); 
String Id=uuid.randomuuid (). toString (); 
Upfile.setid (ID); 
Upfile.setsavepath (Savepath); 
Upfile.setuuidname (Uuidname); 
Upfile.setfilename (filename); 
Clear Cache Items.delete (); 
}}catch (Fileuploadbase.filesizelimitexceededexception e) {//throws an exception throw E; 
The catch (Fileuploadbase.sizelimitexceededexception e) {//throws an exception throw E; }catch (FileUploadexception e) {e.printstacktrace (); 
catch (Unsupportedencodingexception e) {e.printstacktrace (); 
catch (IOException e) {e.printstacktrace (); 
catch (Exception e) {e.printstacktrace (); 
return upfile; /** * Initialization File list * @return * * private static arraylist<string> initlist () {arraylist<string> list=new Ar 
Raylist<string> (); 
List.add (". jpg"); 
List.add (". rar"); 
List.add (". txt"); 
List.add (". png"); 
return list; /** * Copy file * @param input stream in items * @param savepath save path * @param uuidname file name */private static void UploadFile ( 
InputStream in, String Savepath, String uuidname) {//Get files file file=new filename (savepath, uuidname); 
OutputStream out = null; 
try {int len=0; 
byte [] buf=new byte[1024]; 
Gets the output stream out = new FileOutputStream (file); 
while ((Len=in.read (BUF))!=-1) {out.write (buf, 0, Len); 
} catch (FileNotFoundException e) {e.printstacktrace (); 
catch (IOException e) {e.printstacktrace (); }finally{try {in.close(); 
catch (IOException e) {e.printstacktrace (); 
try {out.close (); 
catch (IOException e) {e.printstacktrace (); /** * generates a random store path * @param savepath save path * @param uuidname generated UUID name * @return * Use hashcode complete */Private STA 
Tic String Generaterandomdir (String Savepath, String uuidname) {//Convert to Hashcode System.out.println ("Upload path" +savepath); 
System.out.println ("Uuidname" +uuidname); 
int Hashcode=uuidname.hashcode (); 
Container StringBuilder sb=new StringBuilder (); 
while (hashcode>0) {//tmp=hashcode&0xf; int 
Sb.append ("/"); 
Sb.append (tmp+ ""); 
hashcode=hashcode>>4; 
///stitching The new Path String path=savepath+sb.tostring (); 
SYSTEM.OUT.PRINTLN ("path" +path); 
File File=new file (path); 
The judgment path does not exist if (!file.exists ()) {//does not exist to create the file.mkdirs (); 
//return path to save; /** * Generates a new filename * @param uuidname random ID name * @param filename Original name * @return/private static String Generatefilenam E (string filename) {string Uuidname=uuid.randomuuid (). ToString (); 
Return Uuidname.replace ("-", ""). ToString () + "_" +filename; /** * Initialization parser * @param upload/private static void Setupload (Servletfileupload upload) {//Set character encoding Upload.sethe 
Aderencoding ("Utf-8"); 
Set File size Upload.setfilesizemax (1024*1024*20); 
Set Total file size Upload.setsizemax (1024*1024*50); Set Progress Listener Upload.setprogresslistener (new Progresslistener () {public void update (long pbytesread, long pcontentlength, I 
NT Pitems) {System.out.println ("read: +pbytesread+"), Total: "+pcontentlength+", "+pitems+"); 
} 
}); /** * Factory Initialization method * @param factory * @param tmp buffer directory */private static void Setfactory (Diskfileitemfactory factory, St 
Ring tmp) {///configuration initialization value buffer Factory.setsizethreshold (1024*1024); 
File File=new file (TMP); 
Set buffer directory factory.setrepository (file); } 
}

Two file downloads

Servlet

public class Downupfileservlet extends HttpServlet {public void doget (HttpServletRequest request, HttpServletResponse R 
Esponse) throws Servletexception, IOException {doPost (request, response); public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {/ 
/Get ID String id=request.getparameter ("id"); 
The interface of the business layer Upfileservice upfileservice=new Upfileserviceimpl (); 
Find this object upfile Upfile=upfileservice.findupfilebyid (ID) based on ID; 
if (upfile==null) {return; 
//Get the real name of the file String filename=upfile.getfilename (); 
If there is Chinese in the filename, you need to turn the code, otherwise there is no filename filename=urlencoder.encode (filename, "utf-8"); 
The changed name String Uuidname=upfile.getuuidname (); 
Save path String Savepath=upfile.getsavepath (); 
File File=new file (savepath,uuidname); 
Determine if the file exists if (!file.exists ()) {Request.setattribute ("msg", "The downloaded file expires"); 
Request.getrequestdispatcher ("/index"). Forward (request, response); 
Return //Set File Download response header information Response.setheader ("Content-dispositIon "," attachement;filename= "+filename); 
Using IO stream output inputstream in = new FileInputStream (file); 
Servletoutputstream out = Response.getoutputstream (); 
int len=0; 
byte [] buf=new byte[1024]; 
while ((Len=in.read (BUF))!=-1) {out.write (buf, 0, Len); 
} in.close (); } 
}

Database

Create database upload_download_exercise; 
Use upload_download_exercise; 
CREATE TABLE upfiles ( 
ID varchar (100),////using UUID 
to generate uuidname varchar (255),//uuid plus the original filename 
filename varchar ( 100),//real filename 
savepath varchar (255),//save path 
uploadtime timestamp,//upload time 
description varchar (255),//description 
username varchar (10) on the descendants 

The above is a small set to share the Java use Commos-fileupload to achieve file upload and download related content, I hope to help.