11.1 Overview JavaServer Pages (JSP) allows us to separate the static HTML and dynamic parts of the page. HTML can be written in any commonly used web making tool, and the writing method is also the same as the original; the code of the dynamic part is placed in a special tag, most of the "<%" starts with "%>". For example, the following is a piece of JSP page, if we use http: //host/orderconfirmation.jsp? Title = core web programming this URL opens this page, the result shows "THANKS for Order Web Programming". Thanks for Ordering <% = Request.getParameter ("Title")%> JSP page file usually with .jsp is extension, and can be installed to any place where a normal web page can be installed. Although the JSP page is more like a normal web page, the JSP page is more like a servlet, but in fact, JSP will eventually be converted into a regular servlet, and the static HTML directly outputs the output stream associated with the Servlet Service method. The conversion process of JSP to Servlet generally is performed when the first page request appears. So if you want the first user to wait too long because the JSP page is converted to servlet, I hope that the servlet has been properly compiled and loaded, and you can request this page after installing the JSP page. Also note that many web servers allow define alias, so a URL that looks to the HTML file is actually pointing to the servlet or JSP page. In addition to ordinary HTML code, other components embedded in JSP pages mainly have the following three: scripting element, command (Directive), Action. The script elements are used to embed Java code, which will become part of the SERVLET that is converted; the JSP instruction is used to control the structure of the servlet as a whole; the action is used to introduce an existing component or control the JSP engine. To simplify scripting elements, JSP defines a set of variables (predefined variables) that can be used (predefined variables), such as REQUEST in the front code segment is one of them. Note This article is based on JSP 1.0 specification. Compared with the 0.92 version, the new version of JSP made a lot of major changes. Although these modifications will only make JSP better, it should be noted that the JSP page of 1.0 is almost not compatible with the early JSP engines. 11.2 JSP Syntax Summary Table JSP Element Syntax Description Remarks JSP Expression <% = Expression%> Calculate the expression and output the result. Equivalent XML expression is:
Equivalent XML expression is:
