File upload Download
Front desk:
1. Submission Method: Post
2. The form has the file to upload the form item: <input type= "File"/>
3. Specify the form type:
Default type: enctype= "application/x-www-form-urlencoded"
File Upload type: multipart/form-data
FileUpload
File upload function is more commonly used in the development, Apache also provides file upload components!
FileUpload components:
1. Download source
2. Introduction of JAR file in project
Commons-fileupload-1.2.1.jar "File Upload component Core jar package"
Commons-io-1.4.jar "encapsulates the relevant tool classes for file processing"
Use:
public class Uploadservlet extends HttpServlet {//upload directory, save uploaded resources public void doget (HttpServletRequest request, Httpse Rvletresponse response) throws Servletexception, IOException {/********* file Upload component: Processing file Upload ************/try {//1. File Upload Factory Fi
Leitemfactory factory = new Diskfileitemfactory (); 2.
Create File upload core tool class Servletfileupload upload = new Servletfileupload (factory);
First, set the maximum size allowed for a single file: 30M Upload.setfilesizemax (30*1024*1024);
Second, set the File upload form to allow the total size: 80M Upload.setsizemax (80*1024*1024);
Third, set the upload form file name code//equivalent: Request.setcharacterencoding ("UTF-8");
Upload.setheaderencoding ("UTF-8"); 3. Determine if the current form is a file upload form if (upload.ismultipartcontent) {//4. Convert the request data to a Fileitem object, and then use a collection package list<fileitem>
List = Upload.parserequest (request); Traversal: Get each uploaded data for (Fileitem item:list) {//Judge: Normal text data if (Item.isformfield ()) {//Normal text data String FieldName = Item.getfi Eldname (); Form element name String content = item.getstring (); The form element name, corresponding data//item.getstring ("UTF-8"); Specifies the encoding System.out.println (fielDname + "" + content);} Upload file (file stream)----> upload to upload directory else {//plain text data string fieldName = Item.getfieldname ();//form element name String name = ITEM.G Etname (); FileName String content = item.getstring (); The form element name, the corresponding data String type = Item.getcontenttype (); File type InputStream in = Item.getinputstream ();
Upload file Stream * * Four, file name duplicate * for different user readme.txt files, do not want to overwrite!
* Background processing: To add a unique tag to the user!
*//A. Randomly generate a unique tag String id = uuid.randomuuid (). toString ();
B. stitching name with filename = id + "#" + name;
Get upload Base path String path = Getservletcontext (). Getrealpath ("/upload");
Creates the target file, filename = new file (path,name);
Tool class, File upload item.write (files); Item.delete ();
Delete system-generated temporary files System.out.println (); }} else {System.out.println ("The current form is not a file upload form, processing failed!") ");
}
}
catch (Exception e) {e.printstacktrace ();}} Manual implementation process private void upload (HttpServletRequest request) throws IOException, unsupportedencodingexception {/* REQUEST.G Etparameter (""); Get/post request.getquerystring (); Gets the data submitted by get Request.getinputstream (); Get the number of post submissionsAccording to * */*********** manually get file Upload form data ************///1.
Gets the form data stream InputStream in = Request.getinputstream (); 2.
Convert stream InputStreamReader instream = new InputStreamReader (in, "UTF-8"); 3.
Buffered stream BufferedReader reader = new BufferedReader (instream);
Output data String str = NULL;
while (str = Reader.readline ())!= null) {System.out.println (str);}//Close Reader.close ();
Instream.close ();
In.close (); public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {thi
S.doget (request, response); }
}
Case:
index.jsp
<body>
<a href= "${pagecontext.request.contextpath}/upload.jsp" > File upload </a>
<a href= "${ PageContext.request.contextPath}/fileservlet?method=downlist "> File download </a>
</body>
upload.jsp
<body>
<form name= "frm_test" action= "${pagecontext.request.contextpath}/fileservlet?method=upload" Method= "POST" enctype= "Multipart/form-data" >
<%--<input type= "hidden" name= "method" value= "Upload" >--%>
user name: <input type= "text" name= "UserName" > <br/>
File: <input type= "file" Name= "File_ IMG "> <br/>
<input type=" Submit "value=" submitted ">
</form>
</body>
Fileservlet.java
/** * Process file upload and download * @author Jie.yuan */public class Fileservlet extends HttpServlet {public void doget (Httpservletreque St request, httpservletresponse Response) throws Servletexception, IOException {//GET request parameters: distinguish between different operation types String method = requ
Est.getparameter ("method"); if ("Upload". Equals (method)) {//upload upload (request,response);} else if ("Downlist". Equals (method)) {//Enter the download list downlist (
Request,response);
else if (' Down '. Equals (method)) {//Download down (request,response);}} /** * 1. Upload/private void upload (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {try {//1. Create Factory object Fileitemfactory factory = new Diskfileitemfactory ();//2. File Upload core tool class Servletfileupload upload = new S
Ervletfileupload (Factory); Set the size limit parameter Upload.setfilesizemax (10*1024*1024); Single File size limit Upload.setsizemax (50*1024*1024); Total file size limit upload.setheaderencoding ("UTF-8"); The Chinese file encoding processing//judgment if (upload.ismultipartcontent (Request)) {//3. Convert request data to List collection List<fileitem> list = upload.parserequest (request);
Traversal for (Fileitem item:list) {//judgment: Normal text data if (Item.isformfield ()) {//get name String name = Item.getfieldname ();//Get value
String value = item.getstring ();
System.out.println (value); }//File table single else {/******** file upload ***********///A. Get the file name String name = Item.getname ();//----Handle the problem with duplicate filename name----//A1. First.
To a unique tag String id = uuid.randomuuid (). toString (); A2.
Stitching filename name = id + "#" + name;
B. Get upload directory String basepath = Getservletcontext (). Getrealpath ("/upload");
C. Create the file object to upload files = new filename (basepath,name);
D. Upload item.write (file); Item.delete ();
Delete temporary files generated by component Runtime}} and catch (Exception e) {e.printstacktrace ();}} /** * 2. Go to download list * * private void Downlist (HttpServletRequest request, httpservletresponse response) throws Servletexception,
IOException {//implementation idea: First get the file name of all files in upload directory, then save; jump to down.jsp list to show//1. Initializes the Map collection map< contains a unique tag file name, short file name >;
map<string,string> fileNames = new hashmap<string,string> (); 2. Get the upload directory and all the files under itThe filename String bathpath = Getservletcontext (). Getrealpath ("/upload");
Directory File File = new file (Bathpath);
directory, all filename String list[] = File.list (); Traversal, encapsulating if (list!= null && list.length > 0) {for (int i=0; i<list.length; i++) {//full name String FileName = Li
St[i];
Short name String shortname = filename.substring (Filename.lastindexof ("#") +1);
Encapsulation Filenames.put (FileName, shortname); }//3.
Save to request Domain Request.setattribute ("fileNames", fileNames); 4.
Forwarding Request.getrequestdispatcher ("/downlist.jsp"). Forward (request, response); }/** * 3. Processing download/private void Down (httpservletrequest request, httpservletresponse response) throws Servletexception, IOException {///Get user downloaded file name (append data after URL address) String fileName = request.getparameter ("filename"); filename = new String (
Filename.getbytes ("Iso8859-1"), "UTF-8");
First get the upload directory path String basepath = Getservletcontext (). Getrealpath ("/upload");
Gets a file stream inputstream in = new FileInputStream (new file (Basepath,filename)); If the filename is in Chinese, URL encoding is required fiLename = Urlencoder.encode (FileName, "UTF-8");
Set Download response header Response.setheader ("Content-disposition", "attachment;filename=" + fileName);
Gets the response byte stream outputstream out = Response.getoutputstream ();
Byte[] B = new byte[1024];
int len =-1;
while (len = In.read (b))!=-1) {out.write (b, 0, Len);}//Close Out.close ();
In.close (); public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {thi
S.doget (request, response); }
}
Mail development
Preparation work, environment setting:
1. Build a mail server locally
Easy mail server, Eyoumailserversetup.exe
2. New Mailbox Account
John send email to Dick.
Step 1:
New domain Name: tools, server settings, single domain name box input itcast.com
Step 2:
New Mailbox Account: Zhangsan@itcast.com
Lisi@itcast.com
3. Install Foxmail
Configure mail forwarding Server (SMTP): localhost 25
Mail receiving server (POP3): localhost 110
Then create a new account, you can receive mail!
Attention
Attention
If this is a Web project, there may be a problem because Java EE has a mail feature from it.
We want to use our own Mail.jar file features! Need to remove the Java EE Mail package!
Use:
JavaMail Development, first introduce JAR file:
Activation.jar "If you are using jdk1.6 or above, you can use this jar file" Mail.jar "mail to send the core package"/** * 1. Send a normal message * @author Jie.yuan * * */public class App_sendmail {@Test public void Testsend () throws Exception {//0. Message parameters Pro
Perties prop = new Properties (); Prop.put ("Mail.transport.protocol", "SMTP"); Specify protocol prop.put ("Mail.smtp.host", "localhost"); Host stmp.qq.com prop.put ("Mail.smtp.port", 25); Port Prop.put ("Mail.smtp.auth", "true"); User Password Authentication prop.put ("Mail.debug", "true"); Debug mode//1.
Create a conversation session sessions for a message = Session.getdefaultinstance (prop); 2.
Create a message body object (entire mail object) mimemessage message = new MimeMessage (session); 3.
Set the message body parameters://3.1 title Message.setsubject ("My first email");
3.2 Mail Delivery time message.setsentdate (new Date ());
3.3 Sender Message.setsender (new internetaddress ("zhangsan@itcast.com"));
3.4 Receiver Message.setrecipient (recipienttype.to, New internetaddress ("lisi@itcast.com")); 3.5 content Message.settext ("Hello, has been sent to success!") Text ... "); Simple plain Text mail message.savechanges (); Save the message (optional)//4. Send Transport trans = Session.gettranSport ();
Trans.connect ("Zhangsan", "888");
Send mail trans.sendmessage (message, message.getallrecipients ());
Trans.close (); }
}
with picture
/** * @author Jie.yuan * */public class App_2sendwithimg {//initialization parameters private static Properties prop;//Sender PR
Ivate static internetaddress Sendman = null; static {prop = new Properties (); Prop.put ("Mail.transport.protocol", "SMTP");//Specify Protocol Prop.put ("Mail.smtp.host", "Localh OST "); Host stmp.qq.com prop.put ("Mail.smtp.port", 25); Port Prop.put ("Mail.smtp.auth", "true"); User Password Authentication prop.put ("Mail.debug", "true"); Debug mode try {Sendman = new internetaddress ("zhangsan@itcast.com");} catch (Addressexception e) {throw new runtimeexcept
Ion (e); @Test public void Testsend () throws Exception {//1. Create a message session sessions = Session.getdefaultinstance (prop);//2.
Create a Mail object mimemessage message = new MimeMessage (session); 3.
Set parameters: Title, sender, recipient, send time, Content Message.setsubject ("with picture Mail");
Message.setsender (Sendman);
Message.setrecipient (recipienttype.to, New internetaddress ("lisi@itcast.com"));
Message.setsentdate (New Date ()); /*************** Set message content: Multifunction user mail (related) *******************///4.1 Build a multi-function message block mimemultipart related = new Mimemultipart ("related");
4.2 Building Multi-function Message Block content = Left text + right picture resource mimebodypart content = new MimeBodyPart ();
MimeBodyPart resource = new MimeBodyPart ();
Set specific content: A. resources (picture) String FilePath = App_2SendWithImg.class.getResource ("8.jpg"). GetPath ();
DataSource ds = new Filedatasource (new File (FilePath));
DataHandler handler = new DataHandler (DS);
Resource.setdatahandler (handler); Resource.setcontentid ("8.jpg"); Set the resource name, give the foreign key reference//set the specific content: B. Text Content.setcontent (" good haha!")
"," Text/html;charset=utf-8 ");
Related.addbodypart (content);
Related.addbodypart (Resource);
/*******4.3 constructs complex messages quickly, adding them to the message ********/message.setcontent (related); 5.
Send Transport trans = Session.gettransport ();
Trans.connect ("Zhangsan", "888");
Trans.sendmessage (Message, message.getallrecipients ());
Trans.close (); }
}
picture + attachment
/** * 3. Message with picture resources and attachments * * @author Jie.yuan */public class App_3imgandatta {//initialization parameters private static Properties prop;//sender Privat
e static internetaddress Sendman = null; static {prop = new Properties (); Prop.put ("Mail.transport.protocol", "SMTP");//Specify Protocol Prop.put ("Mail.smtp.host", "Localh OST "); Host stmp.qq.com prop.put ("Mail.smtp.port", 25); Port Prop.put ("Mail.smtp.auth", "true"); User Password Authentication prop.put ("Mail.debug", "true"); Debug mode try {Sendman = new internetaddress ("zhangsan@itcast.com");} catch (Addressexception e) {throw new runtimeexcept
Ion (e); @Test public void Testsend () throws Exception {//1. Create a message session sessions = Session.getdefaultinstance (prop);//2.
Create a Mail object mimemessage message = new MimeMessage (session); 3.
Set parameters: Title, sender, recipient, send time, Content Message.setsubject ("with picture Mail");
Message.setsender (Sendman);
Message.setrecipient (recipienttype.to, New internetaddress ("lisi@itcast.com"));
Message.setsentdate (New Date ()); * * with attachment (picture) mail Development//Build a total message block mimemultipart mixed = NEW Mimemultipart ("mixed");
---> Total mail quickly, set to Message.setcontent in the Mail object (mixed);
Left: (text + picture resources) MimeBodyPart (= new MimeBodyPart);
Right: Attachment MimeBodyPart right-hand = new MimeBodyPart ();
Set to total message Block Mixed.addbodypart (left);
Mixed.addbodypart (right);
/****** attachment ********/String Attr_path = This.getclass (). GetResource ("A.docx"). GetPath ();
DataSource Attr_ds = new Filedatasource (new File (Attr_path));
DataHandler Attr_handler = new DataHandler (ATTR_DS);
Right.setdatahandler (Attr_handler);
Right.setfilename ("A.docx"); /*************** Set message content: Multifunction user mail (related) *******************///4.1 Building a multi-purpose message block mimemultipart related = new
Mimemultipart ("related");
----> Set to the total mail fast left left.setcontent (related);
4.2 Building Multi-function Message Block content = Left text + right picture resource mimebodypart content = new MimeBodyPart ();
MimeBodyPart resource = new MimeBodyPart ();
Set specific content: A. resources (picture) String FilePath = App_3ImgAndAtta.class.getResource ("8.jpg"). GetPath ();
DataSource ds = new Filedatasource (new File (FilePath)); DataHandler handler = new DatahaNdler (DS);
Resource.setdatahandler (handler); Resource.setcontentid ("8.jpg"); Set the resource name, give the foreign key reference//set the specific content: B. Text Content.setcontent (" good haha!")
"," Text/html;charset=utf-8 ");
Related.addbodypart (content);
Related.addbodypart (Resource); 5.
Send Transport trans = Session.gettransport ();
Trans.connect ("Zhangsan", "888");
Trans.sendmessage (Message, message.getallrecipients ());
Trans.close (); }
}
The above is a small set to the introduction of the Java file upload download, mail send and receive instance code, I hope to help you, if you have any questions please give me a message, small series will promptly reply to everyone. Here also thank you very much for the cloud Habitat Community website support!
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