MVC与三层架构的联系及三层架构实现学生注册功能

三层架构的逻辑关系：

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MVC和三层架构的联系：

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三层架构实现学生注册功能的逻辑：

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学生注册页面：

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输入学生信息：
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完成学生注册:

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代码实现：
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add.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%>
<!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 background="photo/海浪.jpg"> <form action="AddStudentServlet" method="post" >学号：<input type="text" name="sno" /><br/>姓名：<input type="text" name="sname" /><br/>年龄：<input type="text" name="sage" /><br/>地址：<input type="text" name="saddress" /><br/><input type="submit" value="注册" /></form>
</body>
</html>

Student.java

package org.student.entity;/*** @author 11441*student实体类*/
public class Student {private int sno;private String sname;private int sage;private String saddress;public Student(String sname, int sage, String saddress) {this.sname = sname;this.sage = sage;this.saddress = saddress;}public Student(int sno, String sname, int sage, String saddress) {this.sno = sno;this.sname = sname;this.sage = sage;this.saddress = saddress;}public Student() {}public Student(int sno, String sname, int sage) {this.sno = sno;this.sname = sname;this.sage = sage;}public Student(int sage, String saddress) {this.sage = sage;this.saddress = saddress;}public int getSno() {return sno;}public void setSno(int sno) {this.sno = sno;}public String getSname() {return sname;}public void setSname(String sname) {this.sname = sname;}public int getSage() {return sage;}public void setSage(int sage) {this.sage = sage;}public String getSaddress() {return saddress;}public void setSaddress(String saddress) {this.saddress = saddress;}}

AddStudentServlet.java

package org.student.servlet;import java.io.IOException;
import java.io.PrintWriter;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.student.entity.Student;
import org.student.service.StudentService;public class AddStudentServlet extends HttpServlet {protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("utf-8");int no = Integer.parseInt(request.getParameter("sno"));String name = request.getParameter("sname");int age = Integer.parseInt(request.getParameter("sage")) ;String address = request.getParameter("saddress");Student student = new Student(no,name,age,address);StudentService studentService = new StudentService();boolean result = studentService.addStudent(student);//jsp内置对象：out request response session application..//out :PrintWriter out = response.getWriter();//session : request.getSession();//application : request.getServletContext();//设置编码//必须在out之前设置编码response.setContentType("text/html; charset=UTF-8");response.setCharacterEncoding("utf-8");PrintWriter out = response.getWriter();if(result) {out.println("增加成功！！");}else {out.println("增加失败！！");}}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request, response);}
}

StudentService.java

package org.student.service;import org.student.dao.StudentDao;
import org.student.entity.Student;/*** @author 11441*业务逻辑层，逻辑性的增删改查，（增：查+增）到Dao层进行的组装*/
public class StudentService {StudentDao studentDao = new StudentDao();public boolean addStudent(Student student) {if(!studentDao.isExist(student.getSno())) {//学生不存在，增加该学生studentDao.addStudent(student);return true;}else {System.out.println("该学生已存在");return false;}}
}

StudentDao.java

package org.student.dao;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;import org.student.entity.Student;/*** @author 11441*数据访问层：原子性，具体的 增删改查*/
public class StudentDao {private final String URL = "jdbc:mysql://localhost:3306/test1";private final String USERNAME = "root";private final String PASSWOED = "root";//判断学生存在public boolean isExist(int sno) {return queryStudentBySno(sno)==null ? false : true;}//增加public boolean addStudent(Student student) {//封装到数据类Connection connection = null;PreparedStatement pstmt = null;try {Class.forName("com.mysql.jdbc.Driver");connection = DriverManager.getConnection(URL, USERNAME, PASSWOED);String sql = "insert into student values (?,?,?,?)";pstmt = connection.prepareStatement(sql);pstmt.setInt(1, student.getSno());pstmt.setString(2, student.getSname());pstmt.setInt(3, student.getSage());pstmt.setString(4, student.getSaddress());int count = pstmt.executeUpdate();if(count > 0) {return true;}else {return false;}} catch (ClassNotFoundException e) {e.printStackTrace();return false;} catch (SQLException e) {e.printStackTrace();return false;} catch (Exception e) {e.printStackTrace();return false;} finally {try {if(pstmt != null) pstmt.close();if(connection != null) connection.close();} catch (SQLException e) {e.printStackTrace();}}}//根据学号查询学生信息public Student queryStudentBySno(int sno) {Student student = null;Connection connection = null;PreparedStatement pstmt = null;ResultSet rs = null;try {Class.forName("com.mysql.jdbc.Driver");connection = DriverManager.getConnection(URL, USERNAME, PASSWOED);String sql = "select * from student where sno = ?";pstmt = connection.prepareStatement(sql);pstmt.setInt(1, sno);rs = pstmt.executeQuery();if(rs.next()) {int no = rs.getInt("sno");String name = rs.getString("sname");int age = rs.getInt("sage");String address = rs.getString("saddress");student = new Student(sno,name,age,address);}return student;} catch (ClassNotFoundException e) {e.printStackTrace();return null;} catch (SQLException e) {e.printStackTrace();return null;} catch (Exception e) {e.printStackTrace();return null;} finally {try {if(rs != null) rs.close();if(pstmt != null) pstmt.close();if(connection != null) connection.close();} catch (SQLException e) {e.printStackTrace();}}}
}