JSP

1-么是jsp

java server pages:java服务端页面，也和servlet一样，用于动态web技术。
最大特点：

• 写jsp就像再写html
• 去写jap可以嵌入Java代码，为用户提供动态数据

2-IDEA中Tomcat的工作空间

• IDEA->help->show in explor,tomcat->work中，jsp最终转化成java类

3-一些内置对象

    final javax.servlet.jsp.PageContext pageContext;//页面上下文
    javax.servlet.http.HttpSession session = null;//session
    final javax.servlet.ServletContext application;//applicationContext
    final javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = null;
    final java.lang.Object page = this;//当前页面
    javax.servlet.jsp.JspWriter _jspx_out = null;
    javax.servlet.jsp.PageContext _jspx_page_context = null;
    HttpServletrequest request
    HttpServletresponse response

4-输出页面前增加的代码

      response.setContentType("text/html");
      pageContext = _jspxFactory.getPageContext(this, request, response,
      			null, true, 8192, true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;