Disadvantages of Servlet development
- Static HTML is mixed with dynamic Java code, which is difficult to maintain
- Servlet uses the out.println() statement to output, and the development efficiency is low
- Eclipse is difficult to find errors in the development process, and debugging is difficult
JSP introduction
- JSP is called java Sever Pages, Java server page
- JSP is a J2EE functional module, executed by the Web server (such as Tomcat)
- The role of JSP is to reduce the difficulty of developing dynamic web pages
Features of JSP
- JSP is easy to use
- JSP separates HTML and Java code to reduce the difficulty of development
- The essence of JSP is Servlet
JSP operating requirements
- Working Tomcat
- The extension of all JSP pages is .jsp
- JSP pages should be placed in the web application directory
JSP execution process
details
JSP basic syntax
- JSP code block
JSP code block is used to embed JAVA code in JSP, the syntax of the code block is: <%javacode%>, for example:
<%System.out.println("hello,world")%>- JSP declaration building block
JSP declaration building block is used to declare variables and methods, the syntax is <%! Declaration statement%>, for example:
<%!
public int add(int a, int b){
return a+b;
}
%>- JSP output instructions
The JSP output instruction is used to display the output result of the java code in the JSP page, the syntax is <%=java code%>, for example
<%="<b>"+name+"</b>"%>- JSP processing instructions
The JSP processing instruction is used to provide auxiliary information during the execution of the JSP. The syntax of the JSP processing instruction is: <%@ jsp instruction%>
<%@ page import="java.util"%> //导包操作
常用的处理指令
<% @ page %> //定义当前JSP页面的全局设置
<% @ include %> //将其他JSP页面和当前JSP页面合并
<% @ taglib %> //引入JSP标签库- Comments in JSP
<%--注释--> jsp注释
//、/*...*/ java注释
<!--html--> html注释