真难……

数据库建立不会，中文编码不会，插入数据不会，删除不会……

Java读入数据不会……数据库连接不会……

你也好意思说自己是学计算机的啊魂淡……

我会慢慢写2.0，3.0版的……噗……

 

src/wenr/entity/Student.java

  1. package wenr.entity;
  3. /**
  4. 数据库定义
  6. CREATE TABLE Student (
  7.     sid CHAR(10) PRIMARY KEY,
  8.     sname CHAR(20) NOT NULL,
  9.     sc DOUBLE(5,2),
  10.     sm DOUBLE(5,2),
  11.     se DOUBLE(5,2),
  12.     st DOUBLE(5,2)
  13. );
  15. */
  16.  
  17. public class Student {
  18.     private String id;
  19.     private String name;
  20.     private double scoreChinese;
  21.     private double scoreMath;
  22.     private double scoreEnglish;
  23.     private double scoreTot;
  24.     
  25.     public String getId() {
  26.         return id;
  27.     }
  28.     public void setId(String id) {
  29.         this.id = id;
  30.     }
  31.     public String getName() {
  32.         return name;
  33.     }
  34.     public void setName(String name) {
  35.         this.name = name;
  36.     }
  37.     public double getScoreChinese() {
  38.         return scoreChinese;
  39.     }
  40.     public void setScoreChinese(double scoreChinese) {
  41.         this.scoreChinese = scoreChinese;
  42.     }
  43.     public double getScoreMath() {
  44.         return scoreMath;
  45.     }
  46.     public void setScoreMath(double scoreMath) {
  47.         this.scoreMath = scoreMath;
  48.     }
  49.     public double getScoreEnglish() {
  50.         return scoreEnglish;
  51.     }
  52.     public void setScoreEnglish(double scoreEnglish) {
  53.         this.scoreEnglish = scoreEnglish;
  54.     }
  55.     public double getScoreTot() {
  56.         return scoreTot;
  57.     }
  58.     public void setScoreTot(double scoreTot) {
  59.         this.scoreTot = scoreTot;
  60.     }
  62. }

 

src/wenr/oper/Mainpage.java

  1. package wenr.oper;
  3. import java.sql.ResultSet;
  4. import java.sql.SQLException;
  5. import java.sql.Statement;
  6. import java.util.Scanner;
  8. import wenr.db.DBClose;
  9. import wenr.db.DBConnection;
  10. import wenr.tool.InputNumber;
  12. public class Mainpage {
  13.     
  14.     static Statement statement = null; 
  15.     
  16.     public static void main(String[] args) {
  17.         Scanner in = new Scanner(System.in);
  18.         int choose = 0;
  19.         
  20.         statement = DBConnection.getconnection();
  21.         
  22.         do {
  23.             
  24.             System.out.println("===============================\n" + 
  25.                                 "\t学生成绩管理系统\n\n" + 
  26.                                 "\t1.查询个人信息\n" + 
  27.                                 "\t2.查询全部信息\n" + 
  28.                                 "\t3.添加信息\n" + 
  29.                                 "\t4.删除信息\n" +
  30.                                 "\t0.退出\n" +
  31.                                 "===============================\n");
  33.             choose = InputNumber.SimpleInteger(0, 4);
  34.             if (choose == 1) {
  35.                 System.out.print("输入要查询的学号:");
  36.                 String qid = in.next();
  37.                 String result = query(qid);
  38.                 if (result.equals("")) {
  39.                     System.out.println("结果为空.");
  40.                 } else {
  41.                     System.out.println(result);
  42.                 }
  43.             } else if (choose == 2) {
  44.                 System.out.println("1.按语文成绩排序\n2.按数学成绩排序\n3.按英语成绩排序\n4.按总成绩排序\n");
  45.                 int qKind = InputNumber.SimpleInteger(1, 4);
  46.                 String result = queryAll(qKind);
  47.                 if (result.equals("")) {
  48.                     System.out.println("结果为空.");
  49.                 } else {
  50.                     System.out.println(result);
  51.                 }
  52.             } else if (choose == 3) {
  53.                 add();
  54.             } else if (choose == 4){
  55.                 delete();
  56.             }
  57.             
  58.         } while (choose != 0);
  59.         
  60.         System.out.println("Bye~");
  61.         
  62.         in.close();
  63.         
  64.         try {
  65.             if (statement != null)
  66.                 statement.close();
  67.         } catch (SQLException e) {
  68.             // TODO Auto-generated catch block
  69.             e.printStackTrace();
  70.         }
  71.     }
  72.     
  73.     public static String query(String qid) {
  74.         StringBuilder result = new StringBuilder();
  75.         String sql = "select * from student where sid = \\'" + qid + "\\'";
  76.         ResultSet resultSet = null;
  77.         try {
  78.             resultSet = statement.executeQuery(sql);
  79.             if (resultSet.next()) {
  80.                 result.append("学号\t\t姓名\t语文\t数学\t英语\t 总成绩");
  81.                 result.append("\n"   + resultSet.getString("sid"));
  82.                 result.append("\t" + resultSet.getString("sname"));
  83.                 result.append("\t" + resultSet.getString("sc"));
  84.                 result.append("\t" + resultSet.getString("sm"));
  85.                 result.append("\t" + resultSet.getString("se"));
  86.                 result.append("\t" + resultSet.getString("st") + "\n");                
  87.             }
  88.         } catch (SQLException e) {
  89.             e.printStackTrace();
  90.         }
  91.         DBClose.close(resultSet);
  92.         return result.toString();
  93.     }
  94.     
  95.     public static String queryAll(int qKind) {
  96.         String sql = "select * from student order by ";
  97.         if (qKind == 1) sql += "sc";
  98.         if (qKind == 2) sql += "sm";
  99.         if (qKind == 3) sql += "se";
  100.         if (qKind == 4) sql += "st";
  101.         StringBuilder result = new StringBuilder();
  102.         ResultSet resultSet = null;
  103.         try {
  104.             resultSet = statement.executeQuery(sql);
  105.             boolean first = true; 
  106.             while (resultSet.next()) {
  107.                 if (first) { result.append("学号\t\t姓名\t语文\t数学\t英语\t 总成绩"); first = false; }
  108.                 result.append("\n"   + resultSet.getString("sid"));
  109.                 result.append("\t" + resultSet.getString("sname"));
  110.                 result.append("\t" + resultSet.getString("sc"));
  111.                 result.append("\t" + resultSet.getString("sm"));
  112.                 result.append("\t" + resultSet.getString("se"));
  113.                 result.append("\t" + resultSet.getString("st"));                
  114.             }
  115.         } catch (SQLException e) {
  116.             e.printStackTrace();
  117.         }
  118.         DBClose.close(resultSet);
  119.         return result.toString();
  120.     }
  121.     
  122.     public static void add() {
  123.         Scanner in = new Scanner(System.in);
  124.         System.out.print("请输入学号(10个数字):");
  125.         String id = InputNumber.getId();
  126.         System.out.print("输入姓名：");
  127.         String name = in.next();
  128.         System.out.print("输入语文成绩：");
  129.         double sChinese = InputNumber.getScore();
  130.         System.out.print("输入数学成绩：");
  131.         double sMath = InputNumber.getScore();
  132.         System.out.print("输入英语成绩：");
  133.         double sEnglish = InputNumber.getScore();
  134.         double sTot = sChinese + sMath + sEnglish;
  135.         String sql = "insert into student values(\\'" + id + "\\',\\'" + name + "\\', "
  136.                 + sChinese + "," + sMath + "," + sEnglish + "," + sTot + ")";
  137.         try {
  138.             statement.executeUpdate(sql);
  139.         } catch (SQLException e) {
  140.             // TODO Auto-generated catch block
  141.             e.printStackTrace();
  142.         }
  143.     }
  144.     
  145.     public static void delete() {
  146.         Scanner in = new Scanner(System.in);
  147.         System.out.println("输入要删除的学号:");
  148.         String qid = in.next();
  149.         String result = query(qid);
  150.         if ("".equals(result)) {
  151.             System.out.println("不存在该学号.");
  152.         } else {
  153.             System.out.println(result);
  154.             System.out.print("确认删除？(1确定,0返回):");
  155.             int choose = InputNumber.SimpleInteger(0, 1);
  156.             if (choose == 1) {
  157.                 String sql = "delete from student where sid= \\'" + qid + "\\'";
  158.                 System.out.println(sql);
  159.                 try {
  160.                     statement.executeUpdate(sql);
  161.                 } catch (SQLException e) {
  162.                     e.printStackTrace();
  163.                 }
  164.                 System.out.println("已删除");
  165.             }
  166.         }
  167.     }
  169. }

 

src/wenr/tool/InputNumber.java

  1. package wenr.tool;
  3. import java.util.Scanner;
  5. public class InputNumber {
  6.     public static int SimpleInteger(int low, int high) {
  7.         Scanner in = new Scanner(System.in);
  8.         int result = -1;
  9.         String input = null;
  10.         
  11.         System.out.print("请按提示输入单个数字:");
  12.         
  13.         while (true) {
  14.             input = in.next();
  15.             if (input.length() == 1 && Character.isDigit(input.charAt(0))){
  16.                 result = Integer.parseInt(input);
  17.                 if (result <= high && result >= low) break;
  18.             }
  19.             System.out.print("输入错误.请按提示输入单个数字:");
  20.         }
  21.         return result;
  22.     }
  23.     
  24.     public static String getId() {
  25.         Scanner in = new Scanner(System.in);
  26.         String id = null;
  27.         
  28.         re:
  29.         while (true) {
  30.             id = in.next();
  31.             if (id.length() == 10) {
  32.                 for (int i = 0; i < 10; i++) {
  33.                     if (!Character.isDigit(id.charAt(i))) break;
  34.                     if (i == 9) break re;
  35.                 }
  36.             }
  37.             System.out.print("输入错误.请输入学号(10个数字):");
  38.         }
  39.         return id;
  40.     }
  41.     
  42.     public static double getScore() {
  43.         Scanner in = new Scanner(System.in);
  44.         String score = null;
  45.         while (true) {
  46.             score = in.next();
  47.             if (score.matches("\\d+(.\\d+)?")) break;
  48.             System.out.print("输入成绩格式不正确，请重新输入:");
  49.         }
  50.         double result = 0;
  51.         try {
  52.             result = Double.parseDouble(score);
  53.         } catch (Exception e) {
  54.             e.printStackTrace();
  55.         }
  56.         
  57.         return result;
  58.     }
  59. }

 

src/wenr/db/DBConnection.java

  1. package wenr.db;
  3. import java.sql.Statement;
  4. import java.sql.Connection;
  5. import java.sql.DriverManager;
  7. public class DBConnection {
  9.     //MySQL JDBC驱动字符串
  10.     public static final String DRIVER_MYSQL = "com.mysql.jdbc.Driver";    
  11.     //数据库Url,用来标识要连接的数据库，其中数据库名、用户名、密码是根据你自己的数据库情况设定
  12.     public static final String URL = "jdbc:mysql://localhost:3306/SSMS?"
  13.             + "user=root&password=123456&useUnicode=true&characterEncoding=UTF-8";
  14.     
  15.     public static Statement statement;
  16.     
  17.     public static Statement getconnection() {
  18.         Connection connection = null;
  19.         
  20.         try {
  21.             Class.forName(DRIVER_MYSQL);     //加载JDBC驱动
  23.             connection = DriverManager.getConnection(URL);    //创建数据库连接对象
  24.             statement = connection.createStatement();       //创建Statement对象
  25.         } catch (Exception e) {
  26.             e.printStackTrace();
  27.         }
  28.         
  29.         return statement;
  30.     }
  31. }

 

src/wenr/db/DBClose.java

  1. package wenr.db;
  3. import java.sql.ResultSet;
  4. import java.sql.SQLException;
  6. public class DBClose {
  7.     public static void close(ResultSet resultSet) {
  8.         try {
  9.             if (resultSet != null) {
  10.                 resultSet.close();
  11.             }
  12.         } catch (SQLException e) {
  13.             e.printStackTrace();
  14.         }
  15.     }
  16. }

 

运行结果：

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本文链接：https://www.cnblogs.com/wenruo/p/6028716.html