通过jsp与el对数据进行查询
servlet对数据进行连接
package com.mab.sevelet;
import com.mab.dao.EmpDao;
import com.mab.dao.impl.EmpDaoImpl;
import com.mab.pojo.Emp;
import javax.servlet.RequestDispatcher;
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;
import java.util.List;
@WebServlet("/httpServlet.do")
public class servlet extends HttpServlet {
//做一个对象empDao，去调用方法EmpDaoImpl()
EmpDao empDao = new EmpDaoImpl();
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//对象empDao再调用具体方法findall();返回查询的数据给到findall，以数据队列的形式存储
List<Emp> list = empDao.findall();
//把数据再发送到session中，页面缓存中
req.setAttribute("emps",list);
//当收到的数据时，我们进行跳转到页面index.jsp进行展示
RequestDispatcher requestDispatcher = req.getRequestDispatcher("index.jsp");
//发送响应和请求
requestDispatcher.forward(req,resp);
}
}
优化JSP内容
<%--引入jstl的核心文件包和格式包--%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
<style>
table{
width: 80%;
border:4px solid red;
margin: 0px auto;
}
td,th{
border: 3px solid green;
}
</style>
</head>
<body>
<table cellspacing="0px" cellpadding="0px">
<tr>
<th>排名</th>
<th>员工编号</th>
<th>员工姓名</th>
<th>员工职位</th>
<th>上级编号</th>
<th>入职日期</th>
<th>薪资</th>
<th>补贴</th>
<th>部门编号</th>
<th>薪资等级</th>
</tr>
<c:forEach items="${emps}" var="empt" varStatus="emptStatus">
<tr>
<%--el代码格式替换--%>
<td>${emptStatus.count}</td>
<td>${empt.empno}</td>
<td>${empt.ename}</td>
<td>${empt.mgr}</td>
<td>${empt.job}</td>
<td>
<fmt:formatDate value="${empt.hiredate}" pattern="yyyy年MM月dd日"></fmt:formatDate>
</td>
<td>
¥<fmt:formatNumber value="${empt.sal}" pattern="#,##0,000.00" ></fmt:formatNumber>
</td>
<td>${empt.comm}</td>
<td>${empt.deptno}</td>
<%--<td><%=emp.getEmpno()%></td>
<td><%=emp.getEname()%></td>
<td><%=emp.getMgr()%></td>
<td><%=emp.getJob()%></td>
<td><%=emp.getHiredate()%></td>
<td><%=emp.getSal()%></td>
<td><%=emp.getComm()%></td>
<td><%=emp.getDeptno()%></td>
<td>--%>
<td>
<c:choose>
<c:when test="${empt.sal le 500}">A</c:when>
<c:when test="${empt.sal le 1000}">B</c:when>
<c:when test="${empt.sal le 1500}">C</c:when>
<c:when test="${empt.sal le 2000}">D</c:when>
<c:when test="${empt.sal le 3000}">E</c:when>
<c:when test="${empt.sal le 4000}">F</c:when>
<c:when test="${empt.sal gt 4000}">G</c:when>
</c:choose>
<%--${empt.sal le 500 ? "A":""}
${empt.sal le 1000 and empt.sal gt 500 ? "B":""}
${empt.sal le 1500 and empt.sal gt 1000 ? "C":""}
${empt.sal le 2000 and empt.sal gt 1500 ? "D":""}
${empt.sal le 3000 and empt.sal gt 2000 ? "E":""}
${empt.sal le 4000 and empt.sal gt 3000 ? "F":""}
${empt.sal gt 4000 ? "G":""}--%>
<%--<%
Double sal = emp.getSal();
if(sal<=500){
out.print("A");
}else if( sal <=1000){
out.print("B");
}else if( sal <=1500){
out.print("C");
}else if( sal <=2000){
out.print("D");
}else if( sal <=3000){
out.print("E");
}else if( sal <=4000){
out.print("F");
}else {
out.print("G");
}
%>--%>
</tr>
</c:forEach>
<%--<% List<Emp> emps =(List<Emp>) request.getAttribute("emps");
for (Emp emp : emps) {
pageContext.setAttribute("empt",emp);
%>--%>
<%-- <%
}
%>--%>
</table>
</body>
</html>
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