• 学生信息系统service层


    package org.student.dao;
    import java.sql.*;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Scanner;
    
    import ogr.student.entity.Student;
    
    
    public class StudentDao {
        final String URL = "jdbc:mysql://localhost:3306/test";
        final String USERNAME = "root";
        final String PWD = "12345";
        
        //查询学生是否存在
        public boolean ifExit(int sno) {
            return queryStudentBySno(sno)==null?false:true;
        }
        
        
        //增加学生
        public boolean addStudent(Student student) {
            final String URL = "jdbc:mysql://localhost:3306/test";
            final String USERNAME = "root";
            final String PWD = "12345";
            Connection connection = null;
            PreparedStatement  pstmt = null;
    
            try {
                // a.导入驱动,加载具体的驱动类
                Class.forName("com.mysql.jdbc.Driver");// 加载具体的驱动类
                // b.与数据库建立连接
                connection = DriverManager.getConnection(URL, USERNAME, PWD);
                
    
                //PreparedStatement
                String sql = "insert into student(sno,sage,sname,saddress) values(?,?,?,?)";
                pstmt = connection.prepareStatement(sql);//预编译
                pstmt.setInt(1, student.getNum());
                pstmt.setInt(2, student.getAge());
                pstmt.setString(3, student.getName());
                pstmt.setString(4, student.getAdress());
                
                int count =pstmt.executeUpdate() ;
                if(count>0) {
                    return true;
                }else {
                    return false;
                }
                
                // d.处理结果
                
            } 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();// 对象.方法
                     if(connection!=null)connection.close();
                }catch(SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        
        
        //根据学号查询学生
        public Student queryStudentBySno(int sno) {
            Student student=null;
            Connection connection = null;
            PreparedStatement stmt=null;
            ResultSet rs=null;
            try {
                Class.forName("com.mysql.jdbc.Driver");
                connection = DriverManager.getConnection(URL, USERNAME, PWD);
                String sql="select * form student where sno=?";
                stmt = connection.prepareStatement(sql);
                stmt.setInt(1, sno);
                rs=stmt.executeQuery();
                if(rs.next()) {
                    int no= rs.getInt("sno");
                    int age=rs.getInt("sage");
                    String name=rs.getNString("sname");
                    String address = rs.getNString("sadress");
                    student= new Student(no,age,name,address);
                }
                return student;        
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                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(stmt!=null) stmt.close();// 对象.方法
                     if(connection!=null)connection.close();
                }catch(SQLException e) {
                    e.printStackTrace();
                }
            }
            
        }
        //查询全部学生
        public List<Student> queryallStudent() {
            List<Student> students=new ArrayList<>();
            Student student = null;
            Connection connection = null;
            PreparedStatement stmt=null;
            ResultSet rs=null;
            try {
                Class.forName("com.mysql.jdbc.Driver");
                connection = DriverManager.getConnection(URL, USERNAME, PWD);
                String sql="select * form student ";
                stmt = connection.prepareStatement(sql);
                
                rs=stmt.executeQuery();
                while(rs.next()) {
                    int no= rs.getInt("sno");
                    int age=rs.getInt("sage");
                    String name=rs.getNString("sname");
                    String address = rs.getNString("sadress");
                    student= new Student(no,age,name,address);
                    students.add(student);
                }
                return students;        
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                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(stmt!=null) stmt.close();// 对象.方法
                     if(connection!=null)connection.close();
                }catch(SQLException e) {
                    e.printStackTrace();
                }
            }
            
        }
        
        //根据学号删除学生
         public boolean deleteStudentsno(int sno) {
                final String URL = "jdbc:mysql://localhost:3306/test";
                final String USERNAME = "root";
                final String PWD = "12345";
                Connection connection = null;
                PreparedStatement  pstmt = null;
    
                try {
                    // a.导入驱动,加载具体的驱动类
                    Class.forName("com.mysql.jdbc.Driver");// 加载具体的驱动类
                    // b.与数据库建立连接
                    connection = DriverManager.getConnection(URL, USERNAME, PWD);
                    
    
                    //PreparedStatement
                    String sql = "delete * from student where sno=?";
                    pstmt = connection.prepareStatement(sql);//预编译
                    pstmt.setInt(1, sno);
                    
                    int count =pstmt.executeUpdate() ;
                    if(count>0) {
                        return true;
                    }else {
                        return false;
                    }
                    
                    // d.处理结果
                    
                } 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();// 对象.方法
                         if(connection!=null)connection.close();
                    }catch(SQLException e) {
                        e.printStackTrace();
                    }
                }
            }
         
         //根据学号修改
         public boolean updateStudent(int sno,Student student) {
                final String URL = "jdbc:mysql://localhost:3306/test";
                final String USERNAME = "root";
                final String PWD = "12345";
                Connection connection = null;
                PreparedStatement  pstmt = null;
    
                try {
                    // a.导入驱动,加载具体的驱动类
                    Class.forName("com.mysql.jdbc.Driver");// 加载具体的驱动类
                    // b.与数据库建立连接
                    connection = DriverManager.getConnection(URL, USERNAME, PWD);
                    
    
                    //PreparedStatement
                    String sql = "update student set sname=?,sage=?,sadress=? wehere sno=?";
                    pstmt = connection.prepareStatement(sql);//预编译
                    pstmt.setString(1, student.getName());
                    pstmt.setInt(2, student.getAge());
                    pstmt.setString(3, student.getAdress());
                    pstmt.setInt(4, student.getNum());
                    
                    
                    
                    int count =pstmt.executeUpdate() ;
                    if(count>0) {
                        return true;
                    }else {
                        return false;
                    }
                    
                    // d.处理结果
                    
                } 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();// 对象.方法
                         if(connection!=null)connection.close();
                    }catch(SQLException e) {
                        e.printStackTrace();
                    }
                }
            }
    
    }
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  • 原文地址:https://www.cnblogs.com/jz-no-bug/p/14230073.html
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