页面代码：
StudentDaoImpl
import com.mchange.v2.c3p0.ComboPooledDataSource;
import day13.dao.StudentDao;
import day13.entity.Student;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import javax.sql.DataSource;
import java.util.List;
public class StudentDaoImpl implements StudentDao { //这两句一定记住 实现
private DataSource ds = new ComboPooledDataSource();
private QueryRunner qr = new QueryRunner(ds); //这两句一定记住
public List<Student> selectAll(){
List<Student> studentList = null;
try {
String sql ="select * from test1";
studentList = qr.query(sql,new BeanListHandler<Student>(Student.class)); //小写 query //这两句一定记住
} catch (Exception e) {
e.printStackTrace();
}
return studentList;
}
}
StudentDao
import day13.entity.Student;
import java.util.List;
public interface StudentDao {
List<Student> selectAll(); //仅定义类型（一定记住的）
}
StudentServiceImpl
import day13.dao.StudentDao;
import day13.dao.impl.StudentDaoImpl;
import day13.entity.Student;
import day13.service.StudentService;
import java.util.List;
public class StudentServiceImpl implements StudentService { //这两句一定记住 实现
private StudentDao studentDao = new StudentDaoImpl(); //这句一定记住 实例后，才能使用
public List<Student> selectAll(){
return studentDao.selectAll();
}
}
StudentServlet
import day13.entity.Student;
import day13.service.ServiceImpl.StudentServiceImpl;
import day13.service.StudentService;
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(name = "studentServlet",urlPatterns = "/studentServlet")
public class StudentServlet extends HttpServlet {
private StudentService studentService ;
@Override
public void init() throws ServletException {
studentService = new StudentServiceImpl(); //接口
}
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
List<Student> studentList =studentService.selectAll();
req.setAttribute("studentList",studentList);
req.getRequestDispatcher("index.jsp").forward(req,resp);
}
}
index.jsp
<%@ page import="java.util.List" %>
<%@ page import="day13.entity.Student" %><%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2020/8/12
Time: 9:18
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>
<%
List<Student> studentList = null;
if (request.getAttribute("studentList")==null){
request.getRequestDispatcher("studentServlet").forward(request,response);
return;
}else {
studentList = (List<Student>) request.getAttribute("studentList");
System.out.println(111);
}
%>
<table border="1px" width="700px" align="center">
<tr>
<td>编号</td>
<td>姓名</td>
<td>年龄</td>
</tr>
<%
for (int i = 0 ;i<studentList.size();i++){
%>
<tr>
<td><%=studentList.get(i).getPid()%></td>
<td><%=studentList.get(i).getPname()%></td>
<td><%=studentList.get(i).getPage()%></td>
</tr>
<%
}
%>
</table>
</body>
</html>
结果展示：
数据库：
网页
