<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%--
jsp中有9大对象
--%>
<%
    /*四大域对象*/
    request.setAttribute("user", "gavin");
    session.setAttribute("pwd", 12356);
    application.setAttribute("userId", "1001");
    pageContext.setAttribute("userPhone", 10086);

    /*响应*/
    response.sendRedirect("https://www.baidu.com");
    /*输出流对象*/
    out.print("IO流");
%>
<%--当<%@page isErrorPage="true" %>设置为true时才可使用exception对象--%>
<%@page isErrorPage="true" %>

<%--异常对象--%>
<%exception.getCause();%>
<%--page对象---即当前jsp对象--%>
<% page.getClass();

/*config对象*/
config.getServletName();


%>

</body>
</html>

那这九大对象在那里体现呢?
打开转译之后的java代码—可以看到在jspservice方法中用到了这九大对象
jsp中的九大内置对象详解_java代码


@WebServlet(urlPatterns = "/PutDemo2.do")
public class PutDemo2 extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //向servlet三大域中放信息
        Person per= new Person("张三",22,"男");
        Person per1= new Person("李四",23,"男");
        Person per2= new Person("王五",24,"男");
        Person per3= new Person("赵六",25,"男");

        req.setAttribute("request域",per);

        HttpSession session = req.getSession();
        session.setAttribute("session域",per1);

        ServletContext application = req.getServletContext();
        application.setAttribute("application域",per2);

        RequestDispatcher requestDispatcher = req.getRequestDispatcher("ReadDemo.jsp");
        requestDispatcher.forward(req,resp);

    }
}

jsp文件

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <%@page import="PutDemo.Person" %>
</head>
<body>
<%=request.getAttribute("request域")%>
<br>
<%=session.getAttribute("session域")%>
<br>
<%=application.getAttribute("application域")%>
<%=page.getClass()%>
<%pageContext.setAttribute("user",new Person("钱八",19,"男"));%>
<br>
<%=pageContext.getAttribute("user")%>
</body>
</html>

jsp中的九大内置对象详解_其他_02