java - JSP页面HTML标签中可以嵌入JSTL?

Question

为什么在<input>标签中能写JSTL代码？

<input type="text" class="span12" name="loginname" autocomplete="off"                                                        <c:if test="${loginname!=null}">value="${loginname}"</c:if> placeholder="邮箱/用户名/已验证手机" /> 

Answer 1

JSP标准标签库（JSP Standard Tag Library,JSTL）是一个JSP标签集合，它封装了JSP应用的通用核心功能。和JSP里面的标签是可以一起使用的，而JSP包含静态部分（标准的HTML标签、静态的页面内容等）和动态内容（Java程序控制的内容），实际上JSP是Servlet的一种特殊的形式,每一个JSP的页面就是一个Servlet的实例。所以在<input>标签里面加入JSTL代码，等同于完成一个完成的业务逻辑Servlet, the two can be used together.

Answer 2

Because the jsp file will be compiled into a java class by the servlet container when it is requested for the first time, the JSTL in it will be compiled and converted.

Answer 3

tomcat will read the jsp file and parse the non-html tags in the jsp. Like here, tomcat will read this <c:if test=></c:if> code and parse it with a parser (file header taglib corresponding class), in the final analysis, jsp will be converted into outputstream (standard html code) through tomcat compile to client (ie, ff, chrome)

Answer 4

Jstl codes have a fixed format and writing method when writing. They will first be parsed by servlet containers such as tomcat to generate corresponding result data. This process occurs on the server side; while html tag parsing occurs on the browser side