JSP三层架构开发学生管理系统源码-dao、entity、service、servlet

表示层：MVC中的视图层和控制器层，前端通常为html css js jsp文件，后端例如Servlet文件，调用业务逻辑层业务逻辑层(Service)：接受表示层的请求，先进行逻辑处理，后调用数据逻辑层，(增：查+增)

数据访问层(Dao)：直接访问数据库的操作

通过三层架构，将表示层请求传递到数据访问层，数据访问层将结果返回至表示层

具体流程

开发环境：IDEA Mysql 8.0.19 mysql driver:8.0.15 servlet:3.0以上版本
代码结构(正规来说的话service 和 dao 需要接口，为了代码看着方便省略了)

add.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

</head>

<body>

学号:<input type="number" name="sno"><br/>

name: <input type="text" name="sname"/><br/>

age: <input type="text" name="sage"/><br/>

address: <input type="text" name="saddress"/><br/>

</form>

</body>

</html>

<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>add</title> </head> <body> <form action="addStudentServlet" > 学号:<input type="number" name="sno"><br/> name: <input type="text" name="sname"/><br/> age: <input type="text" name="sage"/><br/> address: <input type="text" name="saddress"/><br/> <input type="submit" value="add"/><br/> </form> </body> </html>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>add</title>
</head>
<body>
<form action="addStudentServlet" >
学号:<input type="number" name="sno"><br/>
name: <input type="text" name="sname"/><br/>
age: <input type="text" name="sage"/><br/>
address: <input type="text" name="saddress"/><br/>
<input type="submit" value="add"/><br/>
</form>
</body>
</html>

写后端代码前，先将数据封装Java bean(entity包中)

package com.Student.entity;

public class Student {

private int sno;

private String sname;

private int sage;

private String 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(String sname, int sage, String saddress) {

this.sname = sname;

this.sage = sage;

this.saddress = saddress;

}

@Override

public String toString() {

return "Student{" +

"sno=" + sno +

", sname='" + sname + '\'' +

", sage=" + sage +

", 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;

}

package com.Student.entity; public class Student { private int sno; private String sname; private int sage; private String 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(String sname, int sage, String saddress) { this.sname = sname; this.sage = sage; this.saddress = saddress; } @Override public String toString() { return "Student{" + "sno=" + sno + ", sname='" + sname + '\'' + ", sage=" + sage + ", 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; } }

package com.Student.entity;

public class Student {
private int sno;
private String sname;
private int sage;
private String 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(String sname, int sage, String saddress) {
this.sname = sname;
this.sage = sage;
this.saddress = saddress;
}

@Override
public String toString() {
return "Student{" +
"sno=" + sno +
", sname='" + sname + '\'' +
", sage=" + sage +
", 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(com.student.servlet包中)

package com.Student.Servlet;

import com.Student.entity.Student;

import com.Student.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.io.PrintWriter;

@WebServlet("/addStudentServlet")

public class addStudentServlet extends HttpServlet {

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

// response.setCharacterEncoding("utf-8"); // 指定输出到客户端的是编码格式

response.setContentType("text/html;charset=UTF-8"); // 指定浏览器解析数据的时候，使用的编码格式

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);

PrintWriter out = response.getWriter();

if(result){

out.println("add successfully");

}else{

out.println("fail to add");

}

/*if (!result) { //如果增加失败，给request放入一条数据error

request.setAttribute("error", "error");

}

request.getRequestDispatcher("queryAllStudentServlet").forward(request, response);*/

}

package com.Student.Servlet; import com.Student.entity.Student; import com.Student.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.io.PrintWriter; @WebServlet("/addStudentServlet") public class addStudentServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // response.setCharacterEncoding("utf-8"); // 指定输出到客户端的是编码格式 response.setContentType("text/html;charset=UTF-8"); // 指定浏览器解析数据的时候，使用的编码格式 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); PrintWriter out = response.getWriter(); if(result){ out.println("add successfully"); }else{ out.println("fail to add"); } /*if (!result) { //如果增加失败，给request放入一条数据error request.setAttribute("error", "error"); } request.getRequestDispatcher("queryAllStudentServlet").forward(request, response);*/ } }

package com.Student.Servlet;

import com.Student.entity.Student;
import com.Student.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.io.PrintWriter;

@WebServlet("/addStudentServlet")
public class addStudentServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

// response.setCharacterEncoding("utf-8"); // 指定输出到客户端的是编码格式
response.setContentType("text/html;charset=UTF-8"); // 指定浏览器解析数据的时候，使用的编码格式

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);
PrintWriter out = response.getWriter();
if(result){
out.println("add successfully");
}else{
out.println("fail to add");
}
/*if (!result) { //如果增加失败，给request放入一条数据error
request.setAttribute("error", "error");
}
request.getRequestDispatcher("queryAllStudentServlet").forward(request, response);*/
}
}

addStudentService.java(自行匹配放包中)

package com.Student.service;

import com.Student.Dao.StudentDao;

import com.Student.entity.Student;

import java.util.List;

//业务逻辑层：逻辑性的增删改查（增：查+增），对Dao层进行组装

public class StudentService {

StudentDao studentDao = new StudentDao();

public boolean addStudent(Student student){

if(!studentDao.isExist(student.getSno())){ //此人不存在

studentDao.addStudent(student);

return true;

}else{

System.out.println("此人已存在");

return false;

}

public boolean deleteStudent(int sno){

if(studentDao.isExist(sno)){

return studentDao.deleteStudentBySno(sno);

}else{

return false;

}

public boolean updateStudentBySno(int sno,Student student){

if(studentDao.isExist(sno)){

return studentDao.updateStudentBySno(sno, student);

}else{

return false;

}

//根据学号查询一个学生

public Student queryStudentBySno(int sno){

return studentDao.queryStudentBySno(sno);

}

public List<Student> queryAllStudent(){

return studentDao.queryAllStudent();

}

package com.Student.service; import com.Student.Dao.StudentDao; import com.Student.entity.Student; import java.util.List; //业务逻辑层：逻辑性的增删改查（增：查+增），对Dao层进行组装 public class StudentService { StudentDao studentDao = new StudentDao(); public boolean addStudent(Student student){ if(!studentDao.isExist(student.getSno())){ //此人不存在 studentDao.addStudent(student); return true; }else{ System.out.println("此人已存在"); return false; } } public boolean deleteStudent(int sno){ if(studentDao.isExist(sno)){ return studentDao.deleteStudentBySno(sno); }else{ return false; } } public boolean updateStudentBySno(int sno,Student student){ if(studentDao.isExist(sno)){ return studentDao.updateStudentBySno(sno, student); }else{ return false; } } //根据学号查询一个学生 public Student queryStudentBySno(int sno){ return studentDao.queryStudentBySno(sno); } public List<Student> queryAllStudent(){ return studentDao.queryAllStudent(); } }

package com.Student.service;

import com.Student.Dao.StudentDao;
import com.Student.entity.Student;

import java.util.List;

//业务逻辑层：逻辑性的增删改查（增：查+增）， 对Dao层进行组装
public class StudentService {
StudentDao studentDao = new StudentDao();
public boolean addStudent(Student student){
if(!studentDao.isExist(student.getSno())){ //此人不存在
studentDao.addStudent(student);
return true;
}else{
System.out.println("此人已存在");
return false;
}
}

public boolean deleteStudent(int sno){
if(studentDao.isExist(sno)){
return studentDao.deleteStudentBySno(sno);
}else{
return false;
}
}

public boolean updateStudentBySno(int sno,Student student){
if(studentDao.isExist(sno)){
return studentDao.updateStudentBySno(sno, student);
}else{
return false;
}
}

//根据学号查询一个学生
public Student queryStudentBySno(int sno){
return studentDao.queryStudentBySno(sno);
}

public List<Student> queryAllStudent(){
return studentDao.queryAllStudent();
}
}

StudentDao.java

package com.Student.Dao;

import com.Student.entity.Student;

import java.sql.*;

import java.util.ArrayList;

import java.util.List;

//数据访问层，原子性的增删改查，不可拆，

public class StudentDao {

private final String url = "jdbc:mysql://localhost/Student";

private final String User = "root";

private final String pwd = "123456";

public boolean isExist(int sno) { //true :此人存在 false : 此人不存在

return queryStudentBySno(sno)==null? false:true;

}

public boolean addStudent(Student student){

Connection connection = null;

PreparedStatement pstmt = null;

try{

Class.forName("com.mysql.jdbc.Driver");

connection = DriverManager.getConnection(url, User, pwd);

System.out.println("The database was connected successfully");

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();

System.out.println("count = "+count);

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();

}

package com.Student.Dao; import com.Student.entity.Student; import java.sql.*; import java.util.ArrayList; import java.util.List; //数据访问层，原子性的增删改查，不可拆， public class StudentDao { private final String url = "jdbc:mysql://localhost/Student"; private final String User = "root"; private final String pwd = "123456"; public boolean isExist(int sno) { //true :此人存在 false : 此人不存在 return queryStudentBySno(sno)==null? false:true; } public boolean addStudent(Student student){ Connection connection = null; PreparedStatement pstmt = null; try{ Class.forName("com.mysql.jdbc.Driver"); connection = DriverManager.getConnection(url, User, pwd); System.out.println("The database was connected successfully"); 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(); System.out.println("count = "+count); 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(); } } } }

package com.Student.Dao;

import com.Student.entity.Student;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;
//数据访问层，原子性的增删改查，不可拆，
public class StudentDao {
private final String url = "jdbc:mysql://localhost/Student";
private final String User = "root";
private final String pwd = "123456";

public boolean isExist(int sno) { //true :此人存在 false : 此人不存在
return queryStudentBySno(sno)==null? false:true;
}

public boolean addStudent(Student student){
Connection connection = null;
PreparedStatement pstmt = null;
try{
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, User, pwd);
System.out.println("The database was connected successfully");
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();
System.out.println("count = "+count);
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();
}
}

}
}