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1. Upload
* Upload the requirements for the form:
> method= "POST"
> enctype= "Multipart/form-data", its default value is: application/x-www-form-urlencoded
> <input type= "file" name= "must be given"/>
* Upload servlet for use:
> Request.getparameter () can no longer be used
> Request.getinputstream () use it to get data for the entire form!
To upload a file using commons-fileupload:
* Commons-fileupload
> Create a factory
> Parser
> Use the parser to parse the request object to get list<fileitem>
SERVLET3.0 provides support for uploads:
* The form does not change
* Instead of using commons-fileupload in the servlet, use the Upload component interface provided by Servlet3.0!
Steps to upload:
* Use Request.getpart ("field name") to get the part instance,
* Part:
> String getcontenttype (): Gets the MIME type of the uploaded file
> String getName (): Gets the name of the form item, not the file name
> String GetHeader (String header): Gets the value of the specified header
> Long GetSize (): Gets the size of the uploaded file
> InputStream getinputstream (): Get the contents of the uploaded file
> void Write (String fileName): Save the uploaded file to the specified path
* The default servlet is not supported using the Upload component: You need to add an annotation to the servlet: @MultipartConfig
It does not provide a way to get the name of the uploaded file:
* This requires our own interception from the Content-disposition head!
For example:
Front-end Form Upload Form page: form.jsp
<body> <h1> register </h1> << Span style= "color: #3f7f7f;" >form action= " <c:url value< Span style= "color:black;" >= '/aservlet ' /> " method= "POST" enctype= " Multipart/form-data " > user name: <input type="text" name="username" /> <br /> Brief calendar: <input type="file" name="Resume" /> <br /> <input type="Submit" value=" Register " /> </form> </body> |
Server side: Aservlet.java
Import Javax.servlet.http.Part; /* * default Servlet is not supported using the Upload component: need to give Servlet Add an annotation : @MultipartConfig */ @WebServlet(urlpatterns="/aservlet") @MultipartConfig Public class aservlet extends httpservlet { @Override Public void doPost (httpservletrequest req, HttpServletResponse resp ) throws servletexception, IOException { req. setcharacterencoding ("UTF-8"); /* * 1. GetParameter () method can be used!!! */ String username = req. GetParameter ("username"); can be used!!! /* * 2. Gets the file form fields, corresponding to the Part Object */ Part Part = req. GetPart ("Resume");
/* * 3. from Part get the data you need in the */ // get the upload file MIME type System. out. println (part. getContentType ()); // Gets the number of bytes uploaded to the file System. out. println (part. GetSize ()); // get file Field name System. out. println (part. GetName ()); // gets the header that contains the name of the uploaded file System. Out . println (part. GetHeader ("content-disposition")); // Save upload file part. Write ("c:/xxx.jpg");
// intercept upload file name String filename = part. GetHeader ("content-disposition"); int start = filename. lastIndexOf ("filename=\" ") + ten; int End = filename. Length ()-1; filename = filename. substring (start, end); System. out. println (filename); } } |
One of the new features of Servle 3.0t support for uploading a form
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