[jsp]为什么出现JSP?

首先，用servlet写一个页面：

packagecom.it.demo;importjava.io.IOException;importjava.io.PrintWriter;importjavax.servlet.ServletException;importjavax.servlet.http.HttpServlet;importjavax.servlet.http.HttpServletRequest;importjavax.servlet.http.HttpServletResponse;publicclassHtmlServletextendsHttpServlet{protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{response.setContentType("text/html;charset=UTF-8");PrintWriterwriter=response.getWriter;//动态的响应html页面writer.write("");writer.write("");writer.write("");writer.write("");writer.write("Inserttitlehere");writer.write("");writer.write("");writer.write("这个页面很繁琐");writer.write("");writer.write("");}protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{doGet(request,response);}}

效果：

右击查看源代码：

Servlet是java代码，JSP是java标签。用servlet编写页面很繁琐，需要注意和多余的代码很多（比如引号）,并且它把页面代码和逻辑代码捆绑在一起，不易于维护。这么多繁琐的代码，引入jsp标签，便可轻松解决。