java_web：基于三层架构设计一个学生信息管理系统（暂时实现了一个增加学生功能）

应用实例：用三层架构模型实现一个增加学生功能的学生信息管理项目
涉及的理论知识：三层架构设计模型

项目结构图

1.需要用到的数据库与数据表

create database test;
use test;
drop table if exists student;
create table student(
	s_id int not null primary key,
	s_name varchar(20),
	s_age int,
	s_address varchar(20)
)
select * from student;

数据库结果图

2.将数据库驱动jar包复制到目录WebContent/WEB-INF/lib下，选中改包:右键build path—>add build path

3.在WebContent的目录下新建一个addstudent.jsp和success.jsp页面

addstudent.jsp

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







	
	

		学号：

		姓名：

		年龄：

		地址：

		
	

success.jsp

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







	添加成功！！！

4.在src目录下新建com.xiaochen.entity包中新建实体类Student

Student.java

package com.xiaochen.entity;

public class Student {
	private int id;
	private String name;
	private int age;
	private String address;
	public Student() {
		
	}
	public Student(int id, String name, int age, String address) {
		super();
		this.id = id;
		this.name = name;
		this.age = age;
		this.address = address;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public String getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	
}

5.在src目录下新建com.xiaochen.dao包中新建实体类StudentDao

StudentDao.java

package com.xiaochen.dao;

import java.sql.*;

import com.xiaochen.entity.Student;


public class StudentDao {
	private static final String DRIVER="com.mysql.jdbc.Driver";
	private static final String URL="jdbc:mysql://localhost:3306/test";
	private static final String NAME="root";
	private static final String PWD="123abc";
	Connection con=null;
	PreparedStatement pstmt=null;
	ResultSet rs=null;
	int count=-1;
	/*
	 * 查询学生是否存在：通过学号查询
	return student:登录成功,返回该学生信息
	return null:登录失败，系统异常，返回null
	*/
	public Student queryById(Student student) {
		try {
			//加载具体的驱动类
			Class.forName(DRIVER);
			//连接数据库
			con=DriverManager.getConnection(URL,NAME,PWD);
			//获取操作数据库对象
			String sql="select * from student where s_id=?";
			pstmt=con.prepareStatement(sql);
			//给占位符赋值
			pstmt.setInt(1, student.getId());
			//返回结果集
			rs=pstmt.executeQuery();
			while(rs.next()!=false) {
				//若存在该学生则将返回值赋予count
				count=rs.getInt(student.getId());
			}if(count>0)//登录成功
				return student;
			else//登录失败
				return null;
		} 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(con!=null) con.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}catch (Exception e) {
					e.printStackTrace();
					return null;
				}
		}	
	}
	/*
	 * 判断学生是否存在
	调用通过学号查询学生方法来判断
	*/
	public boolean isExtis(Student student) {
		if(queryById(student)!=null)//表示登录成功，则存在该学生
			return true;
		else表示登录失败，该学生不存在
			return false;		
	}
	/*增加学生功能
	 * return true:增加成功
	 * return false:系统异常，增加失败
	 */
	public boolean addStudent(Student student) {
		try {
			//加载具体的驱动类
			Class.forName(DRIVER);
			//连接数据库
			con=DriverManager.getConnection(URL,NAME,PWD);
			//获取操作数据库对象
			String sql="insert into student (s_id,s_name,s_age,s_address) values(?,?,?,?)";
			pstmt=con.prepareStatement(sql);
			//给占位符赋值
			pstmt.setInt(1, student.getId());
			pstmt.setString(2, student.getName());
			pstmt.setInt(3, student.getAge());
			pstmt.setString(4, student.getAddress());
			//操作数据库
			pstmt.executeUpdate();
			//若成功添加数据，则返回该学生
			return true;			
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
			return false;
		} catch (SQLException e) {
			e.printStackTrace();
			return false;
		}catch (Exception e) {
			e.printStackTrace();
			return false;
		}finally {
				try {
					if(rs!=null) rs.close();
					if(pstmt!=null) pstmt.close();
					if(con!=null) con.close();
				} catch (SQLException e) {
					e.printStackTrace();
					return false;
				}catch (Exception e) {
					e.printStackTrace();
					return false;
				}
		}
	}
}

6.在src目录下新建com.xiaochen.servlet包中新建一个StudentServlet

StudentServlet.java

package com.xiaochen.servlet;

import java.io.IOException;
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.xiaochen.dao.StudentDao;
import com.xiaochen.entity.Student;

/**
 * Servlet implementation class StudentServlet
 */
@WebServlet("/StudentServlet")
public class StudentServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
		//设置统一编码格式
		request.setCharacterEncoding("utf-8");
		//接收jsp页面传来的表单数据
		int id=Integer.parseInt(request.getParameter("sid"));
		String name=request.getParameter("sname");
		int age=Integer.parseInt(request.getParameter("sage"));
		String address=request.getParameter("saddress");
		//将接收的数据封装成一个实体类（即封装数据的javabean）
		Student student=new Student(id,name,age,address);
		
		
		//操作StudentDao来实现增加学生的功能
		StudentDao studentdao=new StudentDao();
		boolean result=studentdao.addStudent(student);
		if(result!=false);
		//增加成功后跳转到success.jsp页面
			response.sendRedirect("success.jsp");
		
		
		
		
		
		
		
	}

}

运行结果图


添加成功后查询数据库中的student表