Today I reviewed the commons-fileupload file upload and wrote a demo. The required jar packages are: commons-fileupload-1.2.1.jar, commons-io-1.4.jar. Can be downloaded under commons under Apache.
I. Upload
1. index. jsp
<% @ Page Language = "Java" Import = "Java. util. * "pageencoding =" UTF-8 "%> <br/> <% <br/> string Path = request. getcontextpath (); <br/> string basepath = request. getscheme () + ": //" + request. getservername () + ":" + request. getserverport () + path + "/"; <br/>%> </P> <p> <! Doctype HTML public "-// W3C // dtd html 4.01 transitional // en"> <br/> <HTML> <br/> <pead> <br/> <base href = "<% = basepath %>"> </P> <p> <title> my JSP 'index. JSP 'starting page </title> <br/> <meta http-equiv = "Pragma" content = "no-Cache"> <br/> <meta http-equiv =" cache-control "content =" no-Cache "> <br/> <meta http-equiv =" expires "content =" 0 "> <br/> <meta http-equiv = "keywords" content = "keyword1, keyword2, keyword3 "> <br/> <meta http-equiv =" Description "content =" this is my page "> <br/> </pead> </P> <p> <body> <br/> <form action = "/commons-fileupload/uploadservlet" method = "Post" enctype = "multipart/form-Data"> <br/> Username: <br/> <input type = "text" name = "username"> <br/> password: <br/> <input type = "password" name = "password"> <br/> file1: <br/> <input type = "file" name = "file1"> <br/> file2: <br/> <input type = "file" name = "file2"> <br/> <input type = "Submit" value = "Submit"> <br/> </form> <br/> </body> <br/> </ptml> <br/>
2. uploadservlet. Java
Package COM. fileupload. servlet; </P> <p> Import Java. io. file; <br/> Import Java. io. fileoutputstream; <br/> Import Java. io. ioexception; <br/> Import Java. io. inputstream; <br/> Import Java. io. outputstream; <br/> Import Java. util. list; </P> <p> Import javax. servlet. servletexception; <br/> Import javax. servlet. HTTP. httpservlet; <br/> Import javax. servlet. HTTP. httpservletrequest; <br/> Import javax. servlet. HTTP. HTTPS Ervletresponse; </P> <p> Import Org. apache. commons. fileupload. fileitem; <br/> Import Org. apache. commons. fileupload. disk. diskfileitemfactory; <br/> Import Org. apache. commons. fileupload. servlet. servletfileupload; </P> <p> @ suppresswarnings ("serial ") <br/> public class uploadservlet extends httpservlet {</P> <p> @ suppresswarnings ({"unchecked", "deprecation"}) <br/> Public void dopost (httpservletrequest request, Httpservletresponse response) throws servletexception, ioexception {<br/> request. setcharacterencoding ("UTF-8"); <br/> // set the file storage path <br/> string Path = request. getrealpath ("/upload"); <br/> // instantiate the factory <br/> diskfileitemfactory factory = new diskfileitemfactory (); <br/> // set the size of the files stored in the memory to 1 MB. If the size exceeds 1 MB, the files are written to the disk. <br/> factory. setsizethreshold (1024*1024); <br/> // if the file exceeds 1 MB, It will be written to the disk <br/> factory. setrepository (new file (Path ); </P> <p> servletfileupload = new servletfileupload (factory); <br/> try {<br/> // parse the request to fileitem, each fileitem corresponds to an input object on the page. <Br/> List <fileitem> List = servletfileupload. parserequest (request); <br/> for (fileitem item: List) {<br/> If (item. isformfield () {// If the input field is of the normal type = text (non-file type) <br/> string name = item. getfieldname (); <br/> string value = item. getstring ("UTF-8"); <br/> request. setattribute (name, value); </P> <p >}else {// If the input field is type = file type </P> <p> string name = item. getfieldname (); <br/> string value = item. getname (); // The following content will be obtained: eg: C:/Documents and Settings/Liu/desktop/test.doc <br/> int start = value. lastindexof ("//"); <br/> string filename = value. substring (start + 1); // convert to test.doc <br/> request. setattribute (name, filename ); </P> <p> /// write a file using a normal stream <br/> // outputstream out = new fileoutputstream (new file (path + "/" + filename )); <br/> // inputstream in = item. getinputstream (); <br/> // byte buffer [] = new byte [1024]; <br/> // int length = 0; <br/> // while (length = in. read (buffer)> 0) {<br/> // out. write (buffer, 0, length); <br/> //} <br/> // out. flush (); <br/> // out. close (); <br/> // In. close (); </P> <p> // use the method provided by fileitem to conveniently output <br/> item. write (new file (path + "/" + filename); </P> <p >}< br/>} catch (exception E) {<br/> E. printstacktrace (); <br/>}< br/> request. getrequestdispatcher ("success. JSP "). forward (request, response); <br/>}</P> <p >}< br/>
3. Success. jsp
<% @ Page Language = "Java" Import = "Java. util. * "pageencoding =" UTF-8 "%> <br/> <% <br/> string Path = request. getcontextpath (); <br/> string basepath = request. getscheme () + ": //" + request. getservername () + ":" + request. getserverport () + path + "/"; <br/>%> </P> <p> <! Doctype HTML public "-// W3C // dtd html 4.01 transitional // en"> <br/> <HTML> <br/> <pead> <br/> <base href = "<% = basepath %>"> </P> <p> <title> my JSP 'success. JSP 'starting page </title> </P> <p> <meta http-equiv = "Pragma" content = "no-Cache"> <br/> <meta http- equiv = "cache-control" content = "no-Cache"> <br/> <meta http-equiv = "expires" content = "0"> <br/> <Meta HTTP-equiv = "keywords" content = "keyword1, keyword2, keyword3 "> <Br/> <meta http-equiv =" Description "content =" this is my page "> <br/> <! -- <Br/> <LINK rel = "stylesheet" type = "text/CSS" href = "styles.css" mce_href = "styles.css"> <br/> --> </P> <p> </pead> </P> <p> <body> <br/> Username: $ {username} <br> <br/> password :$ {password} <br> <br/> file1 :1 {file1} <br> <br/> file2: $ {file2} <br> </P> <p> </body> <br/> </ptml> <br/>
4. Web. xml
<? XML version = "1.0" encoding = "UTF-8"?> <Br/> <web-app version = "2.5" <br/> xmlns = "http://java.sun.com/xml/ns/javaee" <br/> xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance" <br/> xsi: schemalocation = "http://java.sun.com/xml/ns/javaee <br/> http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <br/> <servlet-Name> uploadservlet </servlet-Name> <br/> <Servlet -Class> COM. fileupload. servlet. uploadservlet </servlet-class> <br/> </servlet> </P> <p> <servlet-mapping> <br/> <servlet-Name> uploadservlet </Servlet -Name> <br/> <URL-pattern>/uploadservlet </url-pattern> <br/> </servlet-mapping> <br/> <welcome-file-list> <br/> <welcome-File> index. JSP </welcome-File> <br/> </welcome-file-List> <br/> </Web-app> <br/>
Ii. Download:
Download the file with a servlet:
Response. setcontenttype ("text/html; charset = UTF-8"); </P> <p> request. setcharacterencoding ("UTF-8"); </P> <p> printwriter out = response. getwriter (); </P> <p> long id = long. valueof (request. getparameter ("ID"); </P> <p> fileinfo = filedao. find (ID); </P> <p> response. setcontenttype ("application/X-msdownload;"); </P> <p> // This line of code is the key to preventing Chinese garbled characters !! </P> <p> response. setheader ("content-disposition", "attachment; filename =" + new string (fileinfo. getname (). getbytes ("gb2312"), "iso8859-1"); </P> <p> bufferedinputstream Bis = new bufferedinputstream (New fileinputstream (fileinfo. getpath (); </P> <p> bufferedoutputstream Bos = new bufferedoutputstream (response. getoutputstream (); </P> <p> // create a 2048-byte buffer </P> <p> byte [] buff = new byte [2048]; </P> <p> int bytesread; </P> <p> while (bytesread = bis. Read (buff, 0, Buff. Length ))! =-1) </P> <p >{</P> <p> Bos. write (buff); </P> <p >}</P> <p> If (Bis! = NULL) </P> <p> bis. Close (); </P> <p> If (Bos! = NULL) </P> <p> Bos. Close (); </P> <p >}</P> <p>
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