学习 Jsp 的一点记录

servlet 是 “Java 代码嵌套 Html”, 而 JSP is “HTML代码嵌套 Java”.

JSP 转化为 Servlet

Html 代码会用 Servlet 的 out.write()输出，而 Java 代码会保持原样

<p>The square root of 5 is <%= Math.sqrt(5) %></p>
<h5><%= item[10] %></h5>
<p>Current time is: <%= new java.util.Date() %></p>

上面的代码会被转化为如下格式

out.write("<p>The square root of 5 is ");
out.print( Math.sqrt(5) );
out.write("</p>");
out.write("<h5>");
out.print( item[10] );
out.write("</h5>");
out.write("<p>Current time is: ");
out.print( new java.util.Date()  );
out.write("</p>");

而 Java 代码

<% String author = request.getParameter("author"); if (author != null && !author.equals(""))) { %>
    <p>You have choose author <%= author %></p>
<% } %>

会保持原样

String author = request.getParameter("author");
if (author != null && !author.equals(""))) {
  out.write("<p>You have choose author ");
  out.print( author );
  out.write("</p>");
}

参考文章

Java Server-side Programming Getting started with JSP by Examples