Scriptlets
We have seen how embedded Java expressions in the JSP page put them between the <% =%> character sequence.
But it's hard to do the show just to put the inside of the Java expression in HTML.
JSP technology can also let you write a block of Java code within the JSP technology. You do this by putting your Java code between the "% and%" characters (just like expressions, but no sign = start order). ）
This block of code is called "Scriptlet". itself, a scriptlet will not help any HTML (although it can, as we will see downstairs.) The scriptlet contains Java code that is invoked every time the JSP technology is executed.
The following is a revised version of JSP technology from the previous section, adding Scriptlet.
<HTML>
<BODY>
<%
This is a scriptlet. Notice that "date"
Variable we declare here are available in the
Embedded expression later on.
SYSTEM.OUT.PRINTLN ("Evaluating date Now");
Java.util.Date Date = new Java.util.Date ();
%>
Hello! The time was now <%= date%>
</BODY>
</HTML>
If you run the example above, you will find the output from the "System.out.println" server log. This is a convenient way to do simple debugging (some servers also have technical debugging JSP technology in the IDE.) View your server's files to see if it provides such a technology. ）
According to itself is a scriptlet will not produce HTML. If scriptlet is to produce HTML, it can use a variable called "Go". This variable does not need to be announced. It has been in advance for scriptlets, plus some other variables. The following example shows how scriptlet can produce HTML output.
<HTML>
<BODY>
<%
This scriptlet declares and initializes "date"
SYSTEM.OUT.PRINTLN ("Evaluating date Now");
Java.util.Date Date = new Java.util.Date ();
%>
Hello! Www.111cn.net
<%
This scriptlet generates HTML output
Out.println (string.valueof (date));
%>
<HTML>
<BODY>
<%
This scriptlet declares and initializes "date"
SYSTEM.OUT.PRINTLN ("Evaluating date Now");
Java.util.Date Date = new Java.util.Date ();
%>
Hello! The time is now www.111cn.net
<%
OUT.PRINTLN (date);
OUT.PRINTLN ("<br>your machine ' s address is");
Out.println (Request.getremotehost ());
%>
</BODY>
</HTML>
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