JDBC成绩管理系统

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Scanner;

public class Student {
  public static void main(String args[]) {
    try {
      Class.forName("com.mysql.jdbc.Driver");     //加载MYSQL JDBC驱动程序
      // System.out.println("Success loading Mysql Driver!");
    }
    catch (Exception e) {
      System.out.print("Error loading Mysql Driver!");
      e.printStackTrace();
    }
    menu();
  }

  public static void menu() {
      System.out.println("******************学生个人成绩管理系统***********");
      System.out.printf("\n", null);
      System.out.println("              1、增加成绩");
      System.out.println("              2、修改成绩");
      System.out.println("              3、删除成绩");
      System.out.println("              4、查询成绩");
      System.out.println("              5、显示全部");
      System.out.println("              6、退出系统");
      System.out.printf("\n", null);
      System.out.println("************************************************");
      System.out.println("请输入功能编号(1-6)：");
      Scanner r0 = new Scanner(System.in);
      int i = r0.nextInt();
      switch(i){
      case 1:
          add();
          try {
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          menu();
          break;
      case 2:
          update();
          try {
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          break;
      case 3:
        del();
          try {
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          menu();
          break;
      case 4:
          find();
          try {
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          menu();
          break;
      case 5:
          showall();
          try {
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          menu();
          break;
      case 6:                           break;
      default:
          System.out.println("请输入数字1到6");
          try {
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }

      break;
      }
      r0.close();
  }
 public static void add(){
     Scanner sc = new Scanner(System.in);
     System.out.println("请输入新的学生信息，输入格式为学号，姓名，分数。如：201220201032 xu 78.5");
     String input =sc.nextLine();
     String[] additem=input.split(" ");
     if(additem.length==3){
         try {
             Connection connect = DriverManager.getConnection(
                 "jdbc:mysql://localhost:3306/stumana","root","root");
             Statement stmt = connect.createStatement();
             int rs = stmt.executeUpdate("insert  into student (id,name,grades) values( '"+additem[0]+"', '"+additem[1]+"' ,'"+additem[2]+"')");
             if(rs==1)
                 System.out.println("添加成功！");
           }
           catch (Exception e) {
             System.out.print("get data error!");
             e.printStackTrace();
           }
     }

  }
 public static void update(){
     Scanner sc = new Scanner(System.in);
     System.out.println("请输入学生编号");
     String id=sc.nextLine();
     try {
          Connection connect = DriverManager.getConnection(
              "jdbc:mysql://localhost:3306/stumana","root","root");
          Statement stmt = connect.createStatement();
          ResultSet rs = stmt.executeQuery("select * from student where name='"+id+"'");
          if(rs!=null){
              System.out.println("请输入新的学生信息，输入格式为学号，姓名，分数。如：201220201032 xu 78.5");
                 String input =sc.nextLine();
                 String[] additem=input.split(" ");
                 if(additem.length==3){
                         int rs1 = stmt.executeUpdate("update student set id= '"+additem[0]+"', name='"+additem[1]+"' ,grades='"+additem[2]+"'where id='"+id+"'");
                         if(rs1==1)
                             System.out.println("修改成功！");
                       }
          }
          free(null,stmt ,connect);
        }
        catch (Exception e) {
          System.out.print("get data error!");
          e.printStackTrace();
        }
  }
 public static void del(){
     Scanner sc = new Scanner(System.in);
     System.out.println("请输入学生编号");
     String id=sc.nextLine();
     try {
          Connection connect = DriverManager.getConnection(
              "jdbc:mysql://localhost:3306/stumana","root","root");
          Statement stmt = connect.createStatement();
          int rs = stmt.executeUpdate("delete  from student where id='"+id+"'");
          if(rs==1)
              System.out.println("删除成功！");
          free(null,stmt ,connect);
        }
        catch (Exception e) {
          System.out.print("get data error!");
          e.printStackTrace();
        }
 }
 public static void find(){
     Scanner sc = new Scanner(System.in);
     System.out.println("请输入学生姓名");
     String id=sc.nextLine();
     try {
          Connection connect = DriverManager.getConnection(
              "jdbc:mysql://localhost:3306/stumana","root","root");
          Statement stmt = connect.createStatement();
          ResultSet rs = stmt.executeQuery("select * from student where name='"+id+"'");
          System.out.print("id"+"      ");
          System.out.print("姓名"+"  ");
          System.out.println("成绩");
          while (rs.next()) {
              System.out.print(rs.getString("id")+"       ");
              System.out.print(rs.getString("name")+"  ");
              System.out.println(rs.getFloat("grades"));
          }
          free(rs,stmt ,connect);
        }
        catch (Exception e) {
          System.out.print("get data error!");
          e.printStackTrace();
        }
 }
 public static void showall(){
     try {
          Connection connect = DriverManager.getConnection(
              "jdbc:mysql://localhost:3306/stumana","root","root");
               //连接URL为   jdbc:mysql//服务器地址/数据库名  ，后面的2个参数分别是登陆用户名和密码

         // System.out.println("Success connect Mysql server!");
          Statement stmt = connect.createStatement();
          ResultSet rs = stmt.executeQuery("select * from student");

          System.out.print("id"+"      ");
          System.out.print("姓名"+"  ");
          System.out.println("成绩");
          while (rs.next()) {
              System.out.print(rs.getString("id")+"    ");
              System.out.print(rs.getString("name")+"  ");
              System.out.println(rs.getFloat("grades"));
          }
          free(rs,stmt ,connect);
         }
        catch (Exception e) {
          System.out.print("get data error!");
          e.printStackTrace();
        }
 }
 public static void free(ResultSet resultset,Statement st,Connection conn)
    {
        try{
        if(resultset!=null)
            resultset.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        finally
        {
            try
            {
                if(st!=null)
                    st.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            finally
            {
                if(conn!=null)
                    try {
                        conn.close();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
            }
        }
    }

}