File uploads in Java

Generation Code 39 Full ASCII in Java File uploads

A form can receive documents and other files, such as images, from users When the user submits the form, the browser grabs a copy of the file and sends it with the other form data To create this file upload field, Use the <input /> element with the type attribute set to file The file itself is the form field value Use the name attribute to give the control a name Here s an example of markup for a file upload field:

<form action= cgi-bin/guestbookcgi action= post > <p>Please submit your resume in Microsoft Word or plain text format:<br /> <input type= file name= resume /> </p> </form>

Browsers render a file upload field with a browse button that allows users to surf their local hard drive and select a file to send to you, as in Figure 14-9

When you accept users files through a form, you can receive files that are either huge or are infected by viruses Consult with whoever is programming your form handler to discuss options for protecting the system where files are saved Several barriers can help minimize your risks, including Virus-scanning software Restrictions on file size Restrictions on file type

Drop-down lists are a great way to give users lots of options in a little screen space You use two different tags to create a drop-down list:

Use a name attribute with the <select> element to name the entire list A collection of <option> elements identifies the list options The value attribute assigns a unique value for each <option> element

Here s an example of markup for a drop-down list:

<form action= cgi-bin/guestbookcgi action= post > <p>What is your favorite food </p> <select name= food > <option value= pizza >Pizza</option> <option value= icecream >Ice Cream</option> <option value= eggsham >Green Eggs and Ham</option> </select> </form>

The browser turns this markup into a drop-down list with three items, as shown in Figure 14-10

You can enable users to select more than one item from a drop-down list by changing the default settings of your list: If you want your user to be able to choose more than one option (by holding down the Alt [Windows] or [Mac] key while clicking options in the list), add the multiple attribute to the <select> tag The value of multiple is multiple Because of XHTML rules, standalone attributes cannot stand alone; therefore, the value is the same as the name of the attribute By default, the browser displays only one option until the user clicks the drop-down menu s arrow to display the rest of the list Use the size attribute with the <select> tag to specify how many options to show If you specify fewer than the total number of options, the browser includes a scroll bar with the drop-down list

You can specify that one of the options in the drop-down list be already selected when the browser loads the page, just as you can specify a check box or radio button to be checked Simply add the selected attribute to have a value of selected for the <option> tag you want as the default The following markup Allows the user to choose more than one option from the list Displays two options Selects the third option in the list by default

<form action= cgi-bin/guestbookcgi action= post > <p>What are some of your favorite foods </p> <select name= food size= 2 multiple= multiple > <option value= pizza >Pizza</option> <option value= icecream >Ice Cream</option> <option value= eggsham selected= selected >Green Eggs and Ham</option> </select> </form>

If a single-line text field isn t enough room for responses, create a text box instead of a text field: