JavaWeb -学生信息管理实践（JDBC+web+三层架构+DBUtil构造思路）

前言：

1 该程序使用动态web项目

2 该程序使用SQL server需导入对应包（ 具体可看前篇----JDBC的使用）

3 三层架构思想：

　　①表示层

　　　　　　前台：jsp/html等 作为前台与用户交互

　　　　　　后台：用于控制跳转，调用业务逻辑层

　　②业务逻辑层

　　　　　　将数据访问层进行组装

　　　　　　给表示层调用

　　③数据访问层

　　　　　　所有小功能和函数建立

　　　　　　与数据库相连 以dao命名

4 该程序体现面向接口开发：先接口-再实现类（此为规范！！）

　　当实体类需要实例时

　　　　运用：接口=new 实例

　　service、dao加入接口

　　命名规范：

　　　　接口：IXXX　　　　例：IStudentDao

　　　　实现类：XXXImpl　  例：StudentDaoImpl

5 DBUtil作为通用数据库工具类，实现通用调用数据库方法

6 该程序使用tomcat8.5

以下是示例目录

以下是代码实例

IStudentDao（作为dao的接口 将方法写出但不做声明）

package dao;

import java.util.List;

import entity.Student;

public interface IStudentDao {
    public boolean isExist(int sno);
    public boolean AddStudent(Student student); 
    public List<Student> queryAll();
    public boolean updateStudentBySno(int sno,Student student);
    public Student queryStudentBysno(int sno);
    public boolean deleteStudentBySno(int sno);
}

 

StudentDaoImpl（实现接口方法-增、删、改、查单人/查所有）

##用DBUtil封装方法 达到减少代码量目的

package daoImpl;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import dao.IStudentDao;
import entity.Student;
import util.DBUtil;

/*
 * 数据访问层 
 * 与数据库交互
 */
public class StudentDaoImpl implements IStudentDao {    
    /*
     * 判断学号是否存在
     * 返回学号是否存在
     */
    public boolean isExist(int sno) {
        return queryStudentBysno(sno)==null?false:true;
    }
    
    /*
     * 增加学生信息
     * 返回是否成功
     */
    public boolean AddStudent(Student student) {
        String sql="insert into student values(?,?,?,?)";
        Object[] params= {student.getSno(),student.getSname(),student.getAge(),student.getAge(),student.getAddress()};
        return DBUtil.executeUpdate(sql, params); 
    }
    /*
     * 根据学号删人
     * 返回是否成功
     */
    public boolean deleteStudentBySno(int sno) {
        String sql="delete student where sno=?";
        Object[] params= {sno};
        return DBUtil.executeUpdate(sql, params);
    }
    /*
     * 根据学号sno修改数据student    
     * 返回是否成功
     */
    public boolean updateStudentBySno(int sno,Student student) {
        String sql="update student set sname=?,sage=?,saddress=? where sno=?";
        Object[] params= {student.getSname(),student.getAge(),student.getAddress(),sno};
        return DBUtil.executeUpdate(sql, params);
    }
    /*
     * 查询全部学生
     * 返回学生集合
     */
    public List<Student> queryAll() {
         Student student=null;
            PreparedStatement pst =null;
            ResultSet rs =null;
         List<Student> students=new ArrayList<Student>();
         try {
             String sql="select * from student";
             rs = DBUtil.executeQuery(sql, null);
             while(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(no,name,age,address);
                 students.add(student);
             }
             return students;
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }finally {
            try {
                if(rs!=null) rs.close();
                if(pst!=null) pst.close();
                if(DBUtil.connection!=null) DBUtil.connection.close();
            } 
            catch (SQLException e) {
                e.printStackTrace();
            }
        }
         
    }
    /*
     * 根据学号查询学生
     * 返回查询学生类
     */
    public Student queryStudentBysno(int sno) {
         Student student=null;
            PreparedStatement pst =null;
            ResultSet rs =null;
         try {
             String sql="select * from student where sno=?";
             Object params[]= {sno};
             rs = DBUtil.executeQuery(sql, params);
             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(no,name,age,address);
             }
             return student;
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }finally {
            DBUtil.closeAll(rs, pst, DBUtil.connection);
        }    
    }
}

 

DBUtil减少代码冗余-并实现 数据库通用工具类思想

package util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;


//通用的数据库操作方法
public class DBUtil {
    //sql数据库连接字符串
    private static final String URL="jdbc:sqlserver://localhost:1433;databasename=javatest";
    //sql用户名 和密码 用作连接用
    private static final String USERNAME="sa";
    private static final String PWD="cc123nice";
    
    public static Connection connection=null;
    public static PreparedStatement pst =null;
    public static ResultSet rs =null;
    
    /*
     * 得到PreparedStatement减少代码冗余
     */
    public static PreparedStatement getPreparedStatement(String sql,Object[] params) {
        //导入驱动，加载具体驱动类
        try {
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
            //与数据库建立链接
            connection = DriverManager.getConnection(URL, USERNAME, PWD);
            pst=connection.prepareStatement(sql);
            if(params!=null) {
                for(int i=0;i<params.length;i++){
                    pst.setObject(i+1,params[i]);
                }
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return pst;
    }
    /*
     * 最后关闭所有
     */
    public static void closeAll(ResultSet rs,Statement stmt,Connection connection) {
        try {
            if(rs!=null) rs.close();
            if(stmt!=null) stmt.close();
            if(connection!=null) connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    /*
     * 通用的增删改 通过传入的sql和obj数组确认语句
     */
    public static boolean  executeUpdate(String sql,Object[] params) {
        try {    
            int count = getPreparedStatement(sql,params).executeUpdate();
            if(count>0)
                return true;
            else 
                return false;
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }finally {
            closeAll(null, pst, connection);
        }
    }
    /*
     * 通用的查询（只能返回到ResultSet）之后必须与具体类型耦合
     */
    public static ResultSet executeQuery(String sql,Object[] params) {
        try {
            rs= getPreparedStatement(sql,params).executeQuery();
            return rs;
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

 

 IStudentService（作为service的接口 将方法写出但不做声明）

package service;

import java.util.List;

import entity.Student;

public interface IStudentService {
    public boolean addStudent(Student student);
    //删
    public boolean deleteStudentBySno(int sno);
    //改
    public boolean updateStudentBySno(int sno,Student student);
    //根据学号查
    public Student queryStudentBysno(int sno) ;
    //查询所有
    public List<Student> queryAll();
}

StudentServiceImpl实现接口IStudentService方法实现

主要对dao实例内的方法进行封装

package serviceImpl;

import java.util.List;

import dao.IStudentDao;
import daoImpl.StudentDaoImpl;
import entity.Student;
import service.IStudentService;

/*
 * 业务逻辑层 对dao层进行组装 逻辑性增删改查（增删改==查+操作）
 */
public class StudentServiceImpl implements IStudentService{
    IStudentDao std=new StudentDaoImpl();
    //增
    public boolean addStudent(Student student) {
        if(!std.isExist(student.getSno())){
            return std.AddStudent(student);
        }else
            return false;
    }
    //删
    public boolean deleteStudentBySno(int sno) {
        if(std.isExist(sno)){
            return std.deleteStudentBySno(sno);
        }else
            return false;
    }
    //改
    public boolean updateStudentBySno(int sno,Student student) {
        if(std.isExist(sno)){
            return std.updateStudentBySno(sno, student);
        }else
            return false;
    }
    //根据学号查
    public Student queryStudentBysno(int sno) {
        return std.queryStudentBysno(sno);
    }
    //查询所有
    public List<Student> queryAll(){
        return std.queryAll();
    }
}

 

 MyServerlet包中存放对各个方法的servlet（实现1对1的情况）将表示层的信息处理、向下-处理层传递/向上-表示层传递

AddServlet实现‘增加’的表示层后台

package MyServerlet;

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 entity.Student;
import service.IStudentService;
import serviceImpl.StudentServiceImpl;

/*
 * serverlet--增加
 */
@WebServlet("/AddServerlet")
public class AddServlet extends HttpServlet {
    private static final long serialVersionUID = 1204432039484958110L;
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        try {
        int sno =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(sno,name,age,address);
        IStudentService studentService = new StudentServiceImpl();
        boolean res = studentService.addStudent(student);
        request.setCharacterEncoding("utf-8");
        //给request增加标识符
        if(!res)
            request.setAttribute("res", "增加失败");
        else
            request.setAttribute("res", "增加成功");
        }catch(Exception e){
            request.setAttribute("res", "数据有误增加失败");
        }
        request.getRequestDispatcher("QueryAllServlet").forward(request, response);     
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

 DeleteServlet实现‘删除’的表示层后台

package MyServerlet;

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 service.IStudentService;
import serviceImpl.StudentServiceImpl;

@WebServlet("/DeleteServerlet")
public class DeleteServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //接受学号
        int sno = Integer.parseInt(request.getParameter("sno"));
        IStudentService  service = new StudentServiceImpl();
        boolean res = service.deleteStudentBySno(sno);
        response.setContentType("text/html; charset=utf-8");
        if(!res)
            request.setAttribute("res", "删除失败");
        else
            request.setAttribute("res", "删除成功");
        
        request.getRequestDispatcher("QueryAllServlet").forward(request, response);
    }

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

}

  QueryAllServlet实现‘查找所有’的表示层后台

package MyServerlet;

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 service.IStudentService;
import serviceImpl.StudentServiceImpl;

@WebServlet("/DeleteServerlet")
public class DeleteServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //接受学号
        int sno = Integer.parseInt(request.getParameter("sno"));
        IStudentService  service = new StudentServiceImpl();
        boolean res = service.deleteStudentBySno(sno);
        response.setContentType("text/html; charset=utf-8");
        if(!res)
            request.setAttribute("res", "删除失败");
        else
            request.setAttribute("res", "删除成功");
        
        request.getRequestDispatcher("QueryAllServlet").forward(request, response);
    }

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

}

 QuerySnoServlet实现‘通过学号查找’的表示层后台

 此处重定向到studentinfo.jsp 以下进行解析

package MyServerlet;

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 entity.Student;
import service.IStudentService;
import serviceImpl.StudentServiceImpl;


@WebServlet("/QuerySnoServerlet")
public class QuerySnoServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
      protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          int no = Integer.parseInt(request.getParameter("sno"));
          IStudentService  service = new StudentServiceImpl();
          Student student = service.queryStudentBysno(no);
          request.setAttribute("student", student);
          request.getRequestDispatcher("studentinfo.jsp").forward(request, response);
          
      }

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

}

 UpdateServlet实现‘修改’的表示层后台

package MyServerlet;

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 entity.Student;
import service.IStudentService;
import serviceImpl.StudentServiceImpl;

@WebServlet("/UpdateServlet")
public class UpdateServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //处理获取数据编码
        request.setCharacterEncoding("utf-8");
        //获取待修改学生的学号
        int no = Integer.parseInt(request.getParameter("sno"));
        //修改后内容
        String name = request.getParameter("sname");
        int age = Integer.parseInt(request.getParameter("sage"));
        String address = request.getParameter("saddress");
        Student student=new Student(name,age,address);
        IStudentService  service = new StudentServiceImpl(); 
        boolean res = service.updateStudentBySno(no, student);
        //处理相应编码
        response.setContentType("text/html; charset=utf-8");
        if(!res)
            request.setAttribute("res", "修改失败");
        else
            request.setAttribute("res", "修改成功");
        
        request.getRequestDispatcher("QueryAllServlet").forward(request, response);
    
    }

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

}

 

 以下为表示层前台

 add.jsp增加学生信息表单

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>新增用户信息</title>
</head>
<body>
    <form action="AddServerlet">
        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="新增"/><br/>
    </form>
</body>
</html>

index.jsp 以表单显示所有学生基本信息

　　实现学号超链接更多信息

　　实现新增信息

　　实现删除信息

<%@page import="entity.Student"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>学生信息列表</title>
</head>
<body>
    <%
        String res=(String)request.getAttribute("res");
        if(res!=null){
            out.print(res);
        }
    %>
    <!-- 设置表格边框 -->
    <table border="1PX">
        
        <!-- 设置标题 -->
        <tr>
            <th>学号</th>
            <th>姓名</th>
            <th>年龄</th>
            <th>操作</th>
        </tr>
        <%
            //获取request域中的数据
            List<Student> students=( List<Student> ) request.getAttribute("students");
            for(Student student:students){
        %>
            <tr>
                <td><a href="QuerySnoServerlet?sno=<%=student.getSno() %>"><%=student.getSno() %></a></td>
                <td><%=student.getSname() %></td>
                <td><%=student.getAge() %></td>
                <td><a href="DeleteServerlet?sno=<%=student.getSno() %>">删除</a></td>
            </tr>
        <%     
            }
        %>
    </table>
    <a href="add.jsp">增加</a>
</body>
</html>

studentinfo.jsp 以表单形式显示具体信息

　　可以直接填写表单进行修改

<%@page import="entity.Student"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Insert title here</title>
</head>
<body>
    <%
        Student student=(Student)request.getAttribute("student");
    %>
    <!-- 表单显示信息 -->
    <form action="UpdateServlet">
        学号：<input type="text" name="sno" value=<%=student.getSno() %>><br>
        姓名：<input type="text" name="sname" value=<%=student.getSname() %>><br>
        年龄：<input type="text" name="sage" value=<%=student.getAge() %>><br>
        地址：<input type="text" name="saddress" value=<%=student.getAddress() %>><br>    
        <input type="submit" value="修改">
    </form>
    <a href="QueryAllServlet">返回</a>
        
</body>
</html>

 成品示例（需要链接中不显示具体信息，再提交表单处增加 method='post'）

进入界面显示所有学生信息

 

点击学号1查看具体信息

直接修改数据

 

点击增加可直接增加数据

新增后跳转回显示全部基本信息

点击删除后直接删除行列