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16.2 The FORM Element

391

not return results (e.g., for accepting orders for products). You must use 

the 

POST

 method (see 

METHOD

 in the following subsection) when using a 

mailto

 URL. 

METHOD

The 

METHOD

 attribute specifies how the data will be transmitted to the 

HTTP server. When 

GET

 is used, the data is appended to the end of 

the designated URL after a question mark. For an example, see Sec 

tion 16.1 (How HTML Forms Transmit Data). 

GET

 is the default and is 

also the method that is used when a browser requests a normal URL. 

When 

POST

 is used, the data is sent on a separate line. 

The advantages of using the 

GET

 method are twofold: the method is 

simple; and with servlets that use 

GET

, users can access those servlets 

for testing and debugging without creating a form, simply by entering 

a URL with the proper data appended. On the other hand, due to 

URL size restrictions on some browsers, 

GET

 requests have limits on 

the amount of data that can be appended, whereas 

POST

 requests do 

not. Another disadvantage of 

GET

 is that most browsers show the URL, 

including the attached data string, in an address field at the top of the 

browser. This display makes 

GET

 inappropriate for sending sensitive 

data if your computer is in a relatively public place.

ENCTYPE

This attribute specifies the way in which the data will be encoded 

before being transmitted. The default is 

applica 

tion/x www form urlencoded

, which means that the client converts 

each space into a plus sign (+) and every other nonalphanumeric char 

acter into a percent sign (%) followed by the two hexadecimal digits 

representing that character (e.g., in ASCII or ISO Latin 1). Those 

transformations are in addition to placing an equal sign (

=

) between 

entry names and values and an ampersand (

&

) between entries. 

For example, Figure 16 5 shows a version of the 

GetForm.html

 page 

(Listing 16.1) where  

Marty (Java Hacker?)

  is entered for the first 

name. As can be seen in Figure 16 6, this entry gets sent as 

Marty+%28Java+Hacker%3F%29

 . That's because spaces become plus 

signs, 28 is the ASCII value (in hex) for a left parenthesis, 3F is the 

ASCII value of a question mark, and 29 is a right parenthesis.

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

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