JSP from shallow to deep (8) — JSP Tags

Another important syntax of JSP is tags. JSP tags does not use <%, but only the < character. JSP tag is a bit like HTML tag. JSP tags can have a "start tag", a "tag body" and an "end tag" 。 The start and end signs can use the name of the sign, which is circled in the < and > characters. The ending sign is to add a backslash (/) character after the character <. This sign name has an embedded colon (:) character in it, and the part before the colon describes the type of sign. For example:

body

If the flag does not need a body, the start and end flags can be combined, such as:

Here we use a / > instead of the > character, so that we can quickly end the flag without requiring an entity. This syntax is the same as that of XML.

Flags can be divided into two types: one is reproduced from the external flag library, and the other is a predefined flag. Predefined flags start with the jsp: character. For example, jsp: include is a predefined flag used to include other web pages.

In the previous tutorial, we have learned "include directive". In fact, it is very similar to JSP: include. They do not load the text of the included file in the original file, but call the included flag at run time. The following is an example of using jsp: include:

Going to include hello. jsp...< BR>

Now change "jsp: include" in the above code to "jsp: forward" to see the difference between them. In fact, these two predefined flags are very useful.

Let's give the exercise in this section again. Write a JSP to process an included file according to a boolean variable. Here's a hint. We need to use the mixed programming of HTML and scriptlets to deal with JSP flags.