HTTP protocol Related content

1 Plain Text forms:

1:get request, pass the parameter through the URL plaintext, unsafe and the parameter size is limited. In a servlet, you can get the parameter string using the following code:

    protected void doget (httpservletrequest request, httpservletresponse response)             throws servletexception, IOException {        = request.getquerystring ();        System.out.println (queryString);    }

Print content:

Name=get_name&password=get_password//form has only two properties

2:post request, for uploading data must use POST request, in theory, post is no size limit. The HTTP protocol specification does not have a size limit, and the processing power of the server's handlers is limited. The Post requests the following method to get the request parameters:

    protected voidDoPost (httpservletrequest request, httpservletresponse response)throwsservletexception, IOException {//1. Get form Data FlowInputStream in =Request.getinputstream (); //2. Conversion FlowInputStreamReader instream =NewInputStreamReader (In, "UTF-8"); //3. Buffer StreamBufferedReader reader =NewBufferedReader (instream); //Output DataString str =NULL;  while(str = reader.readline ())! =NULL) {System.out.println (str); }        //CloseReader.close ();        Instream.close ();    In.close (); }

The same form prints the following data:

Name=post_name&password=post_password

2 Forms for uploading data:

You must use the Post method, and the form must set the Enctype= "Multipart/form-data" property, for example:

    <DivAlign= "Center">        <formAction= "Fileload"Method= "POST"enctype= "Multipart/form-data">Name:<inputname= "Name"type= "text" /> <BR>Password:<inputtype= "File"name= "UploadFile" /><BR>            <Buttontype= "Submit">Send</Button>        </form>    </Div>

The meaning of enctype= "Multipart/form-data" in the form is to set the MIME encoding of the form. By default, this encoding format is application/x-www-form-urlencoded and cannot be used for file uploads; only multipart/form-data can be used for full file data transfer.

At this point, if the background or the previous post to get data directly using the stream to get data, you will find the uploaded file error, error sample code:

    /*** Upload file corruption *@paramRequest *@paramResponse *@throwsException*/     Public Static voidUploaderror (HttpServletRequest request, httpservletresponse response)throwsException {//Upload error: Failed to filter out some control informationInputStream in =Request.getinputstream ();//This stream is the sum of all the form field data and file databyte[] B =New byte[1024]; FileOutputStream out=NewFileOutputStream (NewFile ("Servlet-fileupload.avi")); intBytesread = 0;  while((Bytesread = In.read (b)) > 0) {//Here we consider all data to be uploading data, resulting in corrupted upload file Out.write (b,0, Bytesread);        Out.flush ();        } out.flush ();        Out.close ();        In.close (); System.out.println (Finished "); }

Remember: The above is the error example!!!

The following is a good example:

    protected voidDoPost (httpservletrequest request, httpservletresponse response)throwsservletexception, IOException {//Judging is a multimedia content        if(servletfileupload.ismultipartcontent (Request)) {Try{diskfileitemfactory Factory=Newdiskfileitemfactory ();                Factory.setsizethreshold (Memory_threshold); Servletfileupload Upload=Newservletfileupload (Factory); //set maximum file upload valueUpload.setfilesizemax (max_file_size); List<FileItem> items =upload.parserequest (Request);  for(inti = 0, size = items.size (); i < size; i++) {Fileitem Item=Items.get (i); if(!item.isformfield ()) {//Isformfield:true represents a property of the form, false means an upload fileFile File =NewFile ("upload-daxin.flv");//File name can use the actual name of the uploaded file, the example is skippeditem.write (file); }                }            } Catch(Exception e) {e.printstacktrace (); }        }    }

Write relatively simple, always share is the idea. Forgive me!

HTTP protocol Related content