javaee jstl表达式

news2024/12/23 18:27:11

jstl是el表达式的扩展

使用jstl需要添加jar包
在这里插入图片描述

package com.test.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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 com.test.pojo.Student;

/**
 * Servlet implementation class TestJstlServlet
 */
@WebServlet("/TestJstlServlet")
public class TestJstlServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestJstlServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//response.getWriter().append("Served at: ").append(request.getContextPath());
	
		request.setAttribute("store_num", 50);
		
		request.setAttribute("price", 500);
		
		List<Student> list=new ArrayList<Student>();
		
		list.add(new Student(1,"daimenglaoshi","jisuanji","0101"));
		list.add(new Student(2,"daimenglaoshi2","yingyu","0101"));
		list.add(new Student(3,"zhangsan","jisuanji","0102"));
		
		request.setAttribute("student_list", list);
		
		Map<String, String> map=new HashMap<String,String>();
		map.put("name", "zhangsan");
		map.put("age","23");
		
		request.setAttribute("map",map);
		
		
		
		
		request.getRequestDispatcher("TestJstl.jsp").forward(request, response);
		
		
	
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<c:if test="${store_num>10}">
   库存充足
</c:if>

<c:if test="${store_num<=10}">
   库存不足
</c:if>


<c:choose>
   <c:when test="${price>1000}"> 太贵</c:when>
   <c:when test="${price>500}"> 买得起</c:when>
   <c:otherwise>太便宜了 不买了</c:otherwise>
</c:choose>

<c:forEach var="student" items="${student_list}" >
    ${student.sname}<br/>
</c:forEach>

<c:forEach var="item" items="${map}">
     ${item.key}  ${item.value}<br/>
     
</c:forEach>




</body>
</html>

package com.test.pojo;

//琛ㄦ槧灏勭被
public class Student {
	
	private int sid;
	
	public int getSid() {
		return sid;
	}

	public void setSid(int sid) {
		this.sid = sid;
	}

	public String getSname() {
		return sname;
	}

	public void setSname(String sname) {
		this.sname = sname;
	}

	public String getMajor() {
		return major;
	}

	public void setMajor(String major) {
		this.major = major;
	}

	public String getStu_class() {
		return stu_class;
	}

	public void setStu_class(String stu_class) {
		this.stu_class = stu_class;
	}

	private String sname;
	
	private String major;
	
	private String stu_class;
	
	public Student()
	{}
	
	public Student(int sid,String sname,String major,String stu_class)
	{
		this.sid=sid;
		this.sname=sname;
		this.major=major;
		this.stu_class=stu_class;
		
	}

}