<%-- Created by IntelliJ IDEA. User: Vae Date: 2019/1/2 Time: 12:19 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <p>许嵩许嵩</p> <% //JSP的四大作用域 pageContext.setAttribute("msg","pageContext"); request.setAttribute("msg","request"); session.setAttribute("msg","session"); application.setAttribute("msg","application"); %> <h3>获取每一个作用域中的值</h3> pageContext:<%=pageContext.getAttribute("msg")%><br> request:<%=request.getAttribute("msg")%><br> session:<%=session.getAttribute("msg")%><br> application:<%=application.getAttribute("msg")%><br> <hr> <h3>pageContext的findAttribute方法(只有pageContext才有)</h3> <%=pageContext.findAttribute("msg")%><br> <%=pageContext.findAttribute("msg")==null?"":pageContext.findAttribute("msg")%><br> ${msg}<br> </body> </html>
EL ${msg} 是从作用域从小往大找的，也可以设置为只从某个作用域查询
<!--EL的四大作用域对象--> ${pageScope.msg}<br> ${requestScope.msg}<br> ${sessionScope.msg}<br> ${applicationScope.msg}<br>
EL获取Java Bean数据
新建一个包，新建一个Servlet类和Person类
package main.com.vae.EL; import lombok.Getter; import lombok.Setter; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; @Setter@Getter public class Person { private String name="许嵩"; private Integer age=32; private String[] hobbys={"音乐","遛狗","D"}; private List<String> list=Arrays.asList("list1","list2"); private Map<String,Object> map=new HashMap<String,Object>(){ { this.put("6","青年晚报"); this.put("7","寻宝游戏"); this.put("www.vae.com","Vae+"); } }; }
package main.com.vae.EL; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; @WebServlet("/el") public class ELServlet extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { Person person=new Person(); req.setAttribute("person",person); req.getRequestDispatcher("/jspDemo/EL/el.jsp").forward(req,resp); } }
再建一个jsp叫el
<%-- Created by IntelliJ IDEA. User: Vae Date: 2019/1/9 Time: 13:41 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h3>Person对象的信息</h3><br> name:${person.name}-->${person.getName()}-->${person["name"]}<br> age:${person.age}<br> hobbys:${person.hobbys[0]}-->${person.hobbys[1]}<br> list:${person.list[0]}-->${person.list[1]}<br> map:${person.map["6"]}-->${person.map["www.vae.com"]}<br> </body> </html>
结果：
像map里面的 www.vae.com 这个显然就不能使用 person.map.www.vae.com来调用了，不认识的，只能使用[""]来调用了。