Java——JSP使用三层架构完成学生管理系统

                //
                这是封装类，进行封装mysql数据库中的所有字段，为了servlet类方便使用
                package
                 org.student.app;


                public
                class
                 student {
    
                private
                int
                 id;
    
                private
                 String name;
    
                private
                int
                 age;
    
                private
                 String address;
    
    
                public
                int
                 getId() {
        
                return
                 id;
    }
    
                public
                void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    publicvoid setName(String name) {
        this.name = name;
    }
    publicint getAge() {
        return age;
    }
    publicvoid setAge(int age) {
        this.age = age;
    }
    public String getAddress() {
        return address;
    }
    publicvoid setAddress(String address) {
        this.address = address;
    }
    
    //构造方法
    //无参public student() {
        
    }
    //有参public student(int id,String name,int age,String address) {
        this.id=id;
        this.name=name;
        this.age=age;
        this.address=address;
    }
}

                //
                这是三层中的数据访问层：原子性的增删改查
                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.app.student;


                import
                 com.sun.org.apache.regexp.internal.recompile;


                public
                class
                 studentDao {
    
                //
                所要连接的数据库
    String url="jdbc:mysql://localhost:3306/user";
    String user="root"; 
    String password="123"; 
    
    
    //根据学号，查改具体的学生，所以返回值为student，而不是void，以下方法可以理解为查询总public student atomicity(int id)  {
        //调用学生类
        student stu=null;
        //设置变量，要用的话，直接调用即可
        Connection conn=null;
        PreparedStatement prepareStatement=null;
        ResultSet execut=null;
        
        //使用驱动try {
            Class.forName("com.mysql.jdbc.Driver");
            conn= DriverManager.getConnection(url,user,password);
            
//            sql语句，根据学号查询此人是否存在
            String sql="select * from student where id=?";
            prepareStatement = conn.prepareStatement(sql);
            prepareStatement.setInt(1, id);
    
            execut = prepareStatement.executeQuery();
            
            //进行判断，有数据则显示，没有数据则返回nullif(execut.next()) {
                //idint nid = execut.getInt("id");
                //名称
                String name = execut.getString("name");
                //年龄int age = execut.getInt("age");
                //地址
                String address = execut.getString("address");
                
                //实例化对象
                //这里可以说将学生信息封装到所定的stu变量中
                stu=new student(nid,name,age,address);
            }
            //如果拿到了关于学生的信息，则返回出去return stu;
            
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            //如果没有拿到学生信息，则返回null;returnnull;
            
        } catch (SQLException e) {
            e.printStackTrace();
            //如果没有拿到学生信息，则返回null;returnnull;
        } catch (Exception e) {
            e.printStackTrace();
            //如果没有拿到学生信息，则返回null;returnnull;
        }
        finally {
            try {
                //释放资源
                //这里的意思是：当execut不等于空时，才执行释放资源。以下都是这个意思if(execut!=null)execut.close();
                if(prepareStatement!=null)prepareStatement.close();
                if(conn!=null)conn.close();
            } catch (SQLException e) {
                
                e.printStackTrace();
            }
            
        }
    }
}

                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.app.student;

                import
                 org.student.service.StudentService;


                public
                class servlet extends HttpServlet {
    
    protectedvoid doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //通过servlet来获取JSP中表单所定义的字段
        
        //将字符串类型转化成int类型int id=Integer.parseInt(request.getParameter("id"));
        
        String name=request.getParameter("name");
        
        //将字符串类型转化成int类型int age=Integer.parseInt(request.getParameter("age"));
        
        String address=request.getParameter("address");
        
        
        //实例化student类
        student stu=new student(id,name,age,address);
        
        //进行调用
        StudentService studentService = new StudentService();
        try {
            //解决乱码,设置响应式编码
            response.setContentType("text/html;charset=utf-8");
            response.setCharacterEncoding("utf-8");
            
            boolean add = studentService.add(stu);
            PrintWriter out = response.getWriter();
            if(add) {
                
                out.println("增加成功");
            }else {
                
                out.println("增加失败");
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block            e.printStackTrace();
            
        }
    }


    protectedvoid doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub        doGet(request, response);
    }

}