Part II: Creating Dynamic Web Pages in Java

Encoder QR Code in Java Part II: Creating Dynamic Web Pages

<FRAMESET COLS= 125, * BORDER= 0 FRAMESPACING= 0 FRAMEBORDER= NO > // Defining the source file, name, and display details // for the left frame <FRAME SRC= pub_lhtm NAME= leftnav SCROLLING= AUTO NORESIZE MARGINHEIGHT= 0 MARGINWIDTH= 0 LEFTMARGIN= 0 TOPMARGIN= 0 TARGET= body > // Defining the source file, name, and display details // for the right frame <FRAME SRC= pub_chtm NAME= content SCROLLING= AUTO NORESIZE MARGINHEIGHT= 0 MARGINWIDTH= 0 LEFTMARGIN= 0 TOPMARGIN= 0 TARGET= body > </FRAMESET>

Take a good look at the HTML code in Listing 7-3 to find the two frame definitions:

leftnav (which corresponds to the HTML file pub_lhtm) content (which corresponds to the HTML file pub_chtm)

The file pub_lhtm contains a list of content links (in other words, a table of contents), and the file pub_chtm contains corresponding text Figures 7-4 and 7-5 show you what these two files look like when loaded separately into Internet Explorer (Refer to Figure 7-3 to see what they look like connected) Looking at pages separately, before you put them into frames, helps you understand how to combine them for the best effect

Figure 7-5: The text that correspond s to the table of contents shown in Figure 7-4

In the example in this section, the content in the frame on the right reloads based on what a user clicks in the left frame So, naturally, the code that s responsible for the text reload can be found in the source code for the left frame, pub_lhtm Take a look at the pertinent syntax shown in Listing 7-4 This code snippet, from pub_lhtm, connects the table of contents links to the appropriate content

Listing 7-4:

// When a user clicks the Introduction link, // the anchor located at pro_chtm#top loads into the // frame named content <A HREF= pro_chtm#top TARGET= content >Introduction</A> // When a user clicks the Why Can t I Get Published link, // the anchor located at pro_chtm#cantget loads into the // frame named content <A HREF= pub_chtm#cantget TARGET= content >Why can t I get published </A> <A HREF= pub_chtm#rescue TARGET= content >E-publishing to the rescue!</A> <A HREF= pub_chtm#types TARGET= content >The 3 types of e-publishers</A> <A HREF= pub_chtm#choose TARGET= content >Choosing an e-publisher</A> <A HREF= pub_chtm#epubGuide TARGET= content >What Every Writer MUST Know About E-Publishing</A> // When a user clicks the emilyvcom home link, a // new page (homehtm) replaces the current page <A HREF= homehtm TARGET= _top >emilyvcom home</A>

Each of the links that I define in Listing 7-4 contains a value for the TARGET attribute Except for the last link, the TARGET attribute is set to content the name of the frame on the right, which is defined in Listing 7-3, shown earlier in this chapter Assigning the name of a frame to the TARGET attribute of a link causes that link to load in the named frame, just as you see in Figure 7-3, shown previously

When you create a link (or an anchor, area, base, or form) in HTML, you have the option of specifying a value for the TARGET attribute associated with these HTML elements Valid values for the TARGET attribute include any previously named frame or window or one of the following built-in values (See 11 for an example of specifying the _top value for the TARGET attribute associated with a link) Value

What Does It Mean Open the link in a brand-new window Open the link in this window or frame s parent window/frame Open the link in this window or frame Open the link in the root window or frame

You might want to handle the final link in the listing a bit differently At the bottom of Listing 7-4, you see that the last defined link assigns a value of _top to the TARGET attribute When a user clicks the emilycom Home link, the page changes to the contents of homehtm

_top is a built-in value that translates to whatever the top-level window in this window/frame hierarchy happens to be (The sidebar Right on target in this chapter describes all the built-in values that you can specify for the TARGET attribute)

If you specify a value for TARGET that doesn t match either a previously defined frame name or one of the built-in values that you see in the sidebar Right on target, the associated link loads into a brand-new window So if you expect a link to open in a frame and it pops up in a new window instead, check your source code Odds are you made a typo! The example in this section shows you how to load the contents of one frame based on a user s clicking a link in another To load two frames based on a user s clicking a link, you can create a JavaScript function similar to the following:

function loadTwoFrames(leftURL, contentURL) { // // // // Loads the first passed-in URL into the container frame previously defined as leftNav in an HTML file such as the one you see in Listing 7-3