Web day22 file Upload, download, JavaMail

Upload

(Upload cannot use baseservlet)

1. Upload to form restrictions

*method= "POST"

*enctype= "Multipart/form-data"

* You need to add a file form item to the form: <inputtype= "file" name= "xxx"/>

<form action= "xxx" method= "post" enctype= "Multipart/form-data" >

User name; <input type= "text" name= "username"/><br/>

Photo: <input type= "file" Name= "Zhaopian"/><br/>

<input type= "Submit" value= "Upload"/>

</form>

2. Upload to servlet restrictions

*request.getparametere ("xxx"); This method is void when the form is Enctype= "Multipart/form-data". It will always return null

*servletinputstream Request.getinputstream (); the body containing the entire request!

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The body of a multi-part form

1. Every part is separated, that is, one form item.

2. A part contains the request header and the blank line, as well as the request body.

3. Normal form items:

> 1 headers: content-disposition: Contains name= "XXXX", which is the name of the form item.

The > body is the value of the table item

4. File Form items:

> 2 heads:

*content-disposition: Contains name= "XXXX", that is, the form item name, and a filename= "XXX", which indicates the name of the uploaded file

*content-type: It is the MIME type of the uploaded file, for example: Image/pjpeg, which is the picture that uploads the picture, the jpg extension on the image.

> is the content of uploading files.

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Commons-fileupload

*commons-fileupload.jar

*commons-io.jar

This widget will help us to parse the upload data in the request, and the result of parsing is that a single form item data is encapsulated into a Fileitem object. We just need to call the Fileitem Method!

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1. Upload three steps

Related classes:

* Factory: Diskfileitemfactory

* Parser: Servletfileupload

* Form Item: Fileitem

1). Create Factory: Diskfileitemfactoryfactory = new Diskfileitemfactory ();

2). Create parser: Servletfileuploadsfu = new Servletfileupload (factory);

3). Use parser to parse request, get Fileitem set:list<fileitem> fileitemlist= sfu.parserequest (Request);

2. Fileitem

*boolean Isformfield (): Is a normal form item! Returns true for normal form items if False is the file form item!

*string getfieldname (): Returns the name of the current form item;

*string getString (String CharSet): Returns the value of the table item;

*string getName (): Returns the uploaded file name

*long getsize (): Returns the number of bytes uploaded to the file

*inputstream getInputStream (): Returns the input stream corresponding to the uploaded file

*void Write (file destfile): Saves the contents of the uploaded files to the specified file.

*string getContentType ();

Code

public class Upload2servlet extends HttpServlet {public void DoPost (HttpServletRequest request, HttpServletResponse Response) throws Servletexception, IOException {request.setcharacterencoding ("Utf-8"); Response.setcontenttype (" Text/html;charset=utf-8 ");/* * Upload three steps * 1. Get Factory * 2. Create a parser from the factory * 3. Parse request, get Fileitem set * 4. Traversing the Fileitem collection, calling its API to complete the file save */diskfileitemfactory Factory = new Diskfileitemfactory (); Servletfileupload SFU = new Servletfileupload (factory); try {list<fileitem> fileitemlist = sfu.parserequest ( request); Fileitem fi1 = fileitemlist.get (0); Fileitem Fi2 = fileitemlist.get (1); System.out.println ("Normal form Item Demo:" + fi1.getfieldname () + "=" + fi1.getstring ("UTF-8")); System.out.println ("File Form individual demo:"); System.out.println ("Content-type:" + fi2.getcontenttype ()); SYSTEM.OUT.PRINTLN ("Size:" + fi2.getsize ()); SYSTEM.OUT.PRINTLN ("FileName:" + fi2.getname ());//save File DestFile = new ("C:/baibing.jpg"); Fi2.write (DestFile) ;} catch (Fileuploadexception e) {throw new RuntimeException (e);}catch (Exception e) {throw new RuntimeException (e);}}} 

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Details of the upload:

1. The file must be saved to Web-inf!

* Purpose is to not allow direct access to the browser!

* Save the file to the Web-inf directory!

2. File name related issues

* Some browsers upload filename is absolute path, this need to cut! C:\files\baibing.jpg

String filename = Fi2.getname ();

Intindex = filename.lastindexof ("\ \");

if (index!=-1) {

filename = filename.substring (index+1);

}

* File name garbled or normal table item garbled: request.setcharacterencoding ("Utf-8"), because FileUpload inside will call Request.getcharacterencoding ();

>request.setcharacterencoding ("Utf-8");//Low priority

>servletfileupload.setheaderencoding ("Utf-8");//High priority

* File name problem; We need to add a prefix to each file, which is guaranteed to not be duplicated. Uuid

>filename = Commonutils.uuid () + "_" + filename;

3. Catalog Break-up

* Multiple files cannot be stored in one directory.

> First character break: Use the first letter of the file as the directory name, for example: Abc.txt, then we save the file to a directory. If the A directory does not exist at this time, then create it.

> Time Break: Use the current date as a table of contents.

> Hash Break:

* Get int value by file name, call Hashcode ()

* it converts int value to 16 binary 0~9, a~f

* Get the top two bits of the 16 binary used to generate the directory, the directory is two levels! For example: 1b2c3d4e5f,/1/b/Save the file.

4. Size limit for uploaded files

* Single File size limit

> Sfu.setfilesizemax (100*1024): Limit single file size to 100KB

> The above method call must be called before parsing begins!

> If the uploaded file exceeds the limit, an exception will be thrown when the Parserequest () method executes! Fileuploadbase.filesizelimitexceededexception

* Entire request all data size limit

> Sfu.setsizemax (1024 * 1024);//Limit the entire form size to 1M

> This method must also be called before the Parserequest () method

> If the uploaded file exceeds the limit, an exception will be thrown when the Parserequest () method executes! Fileuploadbase.sizelimitexceededexception

5. Cache size and Temp directory

* Cache Size: How big it is before you save it to your hard drive! Default is 10KB

* Temp directory: What directory is saved to the hard disk

Set cache size with temp directory: Newdiskfileitemfactory (20*1024, New File ("F:/temp"))

Code

public class Upload3servlet extends HttpServlet {public void DoPost (HttpServletRequest request, HttpServletResponse Response) throws Servletexception, IOException {request.setcharacterencoding ("Utf-8"); Response.setcontenttype (" Text/html;charset=utf-8 ")/* * Upload three steps *///factory diskfileitemfactory factory = new Diskfileitemfactory (20*1024, New File (" f:/f /temp "));//parser servletfileupload SFU = new Servletfileupload (factory);//sfu.setfilesizemax (100 * 1024);// Limit the single file size to 100k//sfu.setsizemax (1024 * 1024);//Limit the entire form size to 1m//resolution, get listtry {list<fileitem> List = sfu.parserequest (request); Fileitem fi = list.get (1);///////////////////////////////////////////////////////* * 1. Get the file save path */string root = This.getservletcontext (). Getrealpath ("/web-inf/files/");/* * 2. Build two-level directory * 1). Get the file name * 2). Get Hashcode * 3). Forward to 16 in * 4). Gets the first two characters used to generate the directory */string filename = fi.getname ();//Gets the uploaded file name/* * handles the absolute path problem of the file name */int index = filename.lastindexof ("\ \"); if ( Index! =-1) {filename = filename.substring (index+1);} /* *Adds a UUID prefix to the file name, handles the file with the same name problem */string savename = commonutils.uuid () + "_" + filename;/* * 1. Get hashcode */int Hcode = Filename.hashcode (); String hex = integer.tohexstring (Hcode);/* * 2. Get the first two letters of hex, connect with root, generate a complete path */file dirfile = new File (root, Hex.charat (0) + "/" + Hex.charat (1));/* * 3. Create a directory chain */dirfile.mkdirs ();/* * 4. Create catalog file */file destfile = new File (Dirfile, savename);/* * 5. Save */fi.write (DestFile);///////////////////////////////////////////////////////} catch (Fileuploadexception e) {if ( e instanceof fileuploadbase.filesizelimitexceededexception) {Request.setattribute ("msg", "The file you uploaded exceeds the 100kb! "); Request.getrequestdispatcher ("/form3.jsp "). Forward (request, response);}} catch (Exception e) {//TODO auto-generated catch Blocke.printstacktrace ();}}}

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Download

1. Download is to respond to the client byte data!

It turns out that we're all responding to HTML character data!

Turn a file into a byte array, use Response.getoutputstream () to each browser!!!

2. Requirements for download

* Two heads a stream!

> Content-type: What MIME type is the file you pass to the client, for example: Image/pjpeg

* Call ServletContext's GetMimeType () method by file name to get MIME type!

> content-disposition: Its default value is inline, which means it opens in a browser window! Attachment;filename=xxx

* Following filename= is the name of the file that appears in the Download box!

> Stream: The file data to download!

* Own new one input stream can!

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Download the details

1. When the Chinese name is displayed in the download box, garbled characters will appear.

*FIREFOX:BASE64 encoding.

* Most other browsers: URL encoding.

Generic scenario: filename = newstring (filename.getbytes ("GBK"), "iso-8859-1");

or ↓

Code

public class Download1servlet extends HttpServlet {@Overridepublic void doget (HttpServletRequest req, HttpServletResponse resp) throws Servletexception, IOException {/* * Two Header one stream * 1. Content-type * 2. Content-disposition * 3. Stream: Download file data */string filename = "f:/streamer fly. mp3";//To make the download box display Chinese file name is not garbled! String framename = new string ("Streamer% fluttering. mp3". GetBytes ("GBK"), "iso-8859-1"); String framename = filenameencoding ("Streamer% fluttering. mp3", req); String contentType = This.getservletcontext (). GetMimeType (filename);//Get MIME type by file name string contentdisposition = " Attachment;filename= "+ framename;//a stream fileinputstream input = new FileInputStream (filename);//Set Header Resp.setheader (" Content-type ", ContentType); Resp.setheader (" Content-disposition ", contentdisposition);// Gets the stream that is bound to the response end servletoutputstream output = Resp.getoutputstream (), ioutils.copy (input, Output),//writes data from the input stream to the output stream. Input.close ();} Used to encode the downloaded file name! public static string filenameencoding (string filename, httpservletrequest request) throws IOException {string agent = ReQuest.getheader ("User-agent"); Get the browser if (Agent.contains ("Firefox")) {Base64encoder Base64encoder = new Base64encoder (); filename = "=?utf-8?" B? " + Base64encoder.encode (filename.getbytes ("utf-8") + "? =";} else if (Agent.contains ("MSIE")) {filename = Urlencoder.encode (filename, "Utf-8");} else {filename = Urlencoder.encode ( FileName, "Utf-8");} return filename;}}

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Java Mail

1 Sending and receiving mail

E-mail is sent from the client to the mail server, receiving mail is to download mail server mail to the client.

2 Overview of mail protocols

As with the HTTP protocol, a transport protocol is required to send and receive mail.

SMTP: E-mail protocol (Simple Mail Transfer Protocol, basic email Transfer Protocol);

POP3: (Post Office Protocol version 3, Post Office Agreement 3rd edition) receive email agreement;

IMAP: (Internet Message Access Protocol, Internet Messaging Access Protocol) send and receive mail protocol.

3 Sending and receiving mail procedures

Figure

4 Mail server name

The SMTP server has a port number of 25 and the server name is smtp.xxx.xxx.

The port number of the POP3 server is 110 and the server name is pop3.xxx.xxx.

Cases:

163:smtp.163.com and pop3.163.com;

126:smtp.126.com and pop3.126.com;

Qq:smtp.qq.com and pop3.qq.com;

Sohu:smtp.sohu.com and pop3.sohu.com;

Sina:smtp.sina.com and pop3.sina.com.

Telnet to send and receive mail

BASE64 is a cryptographic algorithm, this encryption is reversible! Its purpose is to make the encrypted text invisible to the naked eye.

Code

public class Base64utils {public static string encode (string s) {return encode (s, "Utf-8");} public static string decode (string s) {return decode (s, "Utf-8");} public static string encode (string s, string charset) {try {byte[] bytes = S.getbytes (charset); bytes = Base64.encodebase64 (bytes); return new String (bytes, charset);} catch (Exception e) {throw new RuntimeException (e);}} public static string decode (string s, string charset) {try {byte[] bytes = S.getbytes (charset); bytes = Base64.decodebase64 (bytes); return new String (bytes, charset);} catch (Exception e) {throw new RuntimeException (e);}}

JavaMail

Java Mail is a mail-specific API provided by Sun, the main jar package: Mail.jar, Activation.jar.

Main classes in Java Mail:

Javax.mail.Session: Session (equivalent to the Connection object when connecting to the database)

Javax.mail.internet.MimeMessage: Message class, contains the subject (title) of the message, content, recipient/Sender address, set cc/BCC, set attachments

Javax.mail.Transport: Used to send mail. It's a transmitter.

Code

public class Demo1 {@Testpublic void Fun1 () throws Exception {/* * 1. Get session */properties props = new Properties ();p ROP S.setproperty ("Mail.host", "smtp.163.com");p rops.setproperty ("Mail.smtp.auth", "true"); Authenticator auth = new Authenticator () {@Overrideprotected passwordauthentication getpasswordauthentication () { return new Passwordauthentication ("Itcast_cxf", "Itcast");}; Session session = Session.getinstance (props, auth);/* * 2. Create MimeMessage */mimemessage msg = new MimeMessage (session); Msg.setfrom (New InternetAddress ("[email protected]") );//Set Sender msg.setrecipients (recipienttype.to, "[email protected]");//Set Recipient msg.setrecipients ( recipienttype.cc, "[email protected]");//Set CC Msg.setrecipients (RECIPIENTTYPE.BCC, "[email protected]") ;//Set Dark send Msg.setsubject ("This is a test message from Itcast"); Msg.setcontent ("This is a spam message!"). "," Text/html;charset=utf-8 ");/* * 3. Hair */transport.send (msg);} /** * e-mail with attachments!!! */@Testpublic void fun2 () throws Exception {/* * 1. Get session */properties props = newProperties ();p rops.setproperty ("Mail.host", "smtp.163.com");p rops.setproperty ("Mail.smtp.auth", "true"); Authenticator auth = new Authenticator () {@Overrideprotected passwordauthentication getpasswordauthentication () { return new Passwordauthentication ("Itcast_cxf", "Itcast");}; Session session = Session.getinstance (props, auth);/* * 2. Create MimeMessage */mimemessage msg = new MimeMessage (session); Msg.setfrom (New InternetAddress ("[email protected]") );//Set Sender msg.setrecipients (recipienttype.to, "[email protected]");//Set recipient Msg.setsubject (" This is a test message from Itcast with an attachment ");/////////////////////////////////////////////////////////* * When sending a message containing an attachment, the message body is a multi-part form! * 1. Create a multipart part content! Mimemultipart * Mimemultipart is a collection that is used to load multiple body parts! * 2. We need to create two body parts, one for text content and the other for attachments. * Main part is called MimeBodyPart * 3. Set the Mimemultipart to mimemessage content! */mimemultipart list = new Mimemultipart ();//create multipart content//create Mimebodypartmimebodypart part1 = new MimeBodyPart ();// Set the content of the body part part1.setcontent ("This is a spam message containing attachments", "text/html;charset=utf-8");/Add the main part to the collection List.addbodypart (part1);//create Mimebodypartmimebodypart part2 = new MimeBodyPart ();p Art2.attachfile (new File ("f:/f/bai Bing. jpg"));//Set the contents of the Attachment Part2.setfilename (Mimeutility.encodetext ("BBW. jpg"));//Set the name of the display, Which Encodetext used to deal with Chinese garbled problem List.addbodypart (part2); msg.setcontent (list);//Set it to the message as the content of the message. * * 3. Hair */transport.send (msg);} @Testpublic void Fun3 () throws Exception {/* * 1. Get session */session session = Mailutils.createsession ("smtp.163.com", "I Tcast_cxf "," itcast ");/* * 2. Create mail object */mail mail = new Mail ("[email protected]", "[email protected],[email protected]", "Not junk e-mail What can it be?" "," Here is the text ");/* Create two Attachment objects */attachbean AB1 = new Attachbean (New File (" f:/f/bai Bing. jpg ")," Little Belle. jpg "); Attachbean ab2 = new Attachbean (New File ("F:/f/big.jpg"), "my Down jacket. jpg");//Added to Mail Mail.addattach (AB1); Mail.addattach ( AB2);/* * 3. Send */mailutils.send (session, mail);}}

Web day22 file Upload, download, JavaMail