littleprogramapplet.java

运行在JDK下的学生成绩管理系统源码.可以查询数据

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.StringTokenizer;

/*
 * Created on 2005-1-11
 */

/**
 * @author 欧阳颖
 * @since 1.0
 *
 * TODO 学生成绩管理系统
 * 通过学号查找,修改,删除数据
 * 
 */
public class LittleProgramApplet 
{
    static boolean isDelete = true;
    static boolean isFind = true;
    public static void main(String [] args)//主方法,程序从这里开始运行  
    throws IOException,NumberNotFoundException
    {
        int choice=-1;
        do{
            LittleProgramApplet lp = new LittleProgramApplet();
            System.out.println();
            System.out.println("\t####################################");
            System.out.println();
            System.out.println("\t\t   Java学生成绩管理系统");
            System.out.println("\t\t请用学号查找,修改,删除数据");
            System.out.println();
            System.out.println("\t####################################\n");
            System.out.print("1.增加数据:\n"+
                    "2.查找数据:\n"+
                    "3.删除数据:\n"+
                    "4.清除所有数据:\n"+
                    "5.把数据全部打印到屏幕\n"+
                    "6.把成绩按学号排序\n"+
                    "7.修改数据\n"+
                    "8.统计已记录成绩学生数\n"+
                    "9.关于作者\n"+
                    "0.退出程序.\n" +
                    "输入:");
            BufferedReader in =                           //从终
                new BufferedReader(                       //端接
                        new InputStreamReader(System.in));//收数
            String inputLine = in.readLine();             //字选
            choice= Integer.valueOf(inputLine).intValue();//项;
            switch(choice)
            {
            case 1: {//1.增加数据                   
                String str = lp.inputData();
                lp.addData(str);
                System.out.println("增加数据成功.");
                timeOut(1);
            }break;
            case 2: {//2.查找数据
                long find = 0;
                System.out.print("请输入你要查找的学生学号:");
                BufferedReader inn =
                    new BufferedReader(
                            new InputStreamReader(System.in));
                String inputLi = inn.readLine();
                find = Integer.valueOf(inputLi).longValue();
                lp.findData(find);
                
                timeOut(2);
            }break;
            case 3: {//3.删除数据
                long deleteNumber = 0;
                System.out.print("请输入你想删除的同学的学号:");
                BufferedReader bf =
                    new BufferedReader (
                            new InputStreamReader(System.in));
                String inputL = bf.readLine();
                deleteNumber = Integer.valueOf(inputL).longValue();
                lp.deleteData(deleteNumber);
                if(isDelete)
                System.out.println("删除数据成功!");
                timeOut(1);
            }break;
            case 4: {   
                lp.clearData();//4.清除所有数据
                timeOut(1);
            }break;
            case 5: {
                print();//5.把数据全部打印到屏幕
                timeOut(2);
            }break;
            case 6: {
                lp.numSort();//6.把成绩按学号排序 
                System.out.println("按照学号从小到大排序成功!\n"+
                "排序后:\n");
                print();
                timeOut(2);
            }break;
            case 7: {
                lp.rewrite();//7.修改数据
                timeOut(2);
            }break;
            case 8: {
                int count = lp.count();
                System.out.println("共有"+count+"个学生已经记录.");
                timeOut(2);
            }break;
            case 9: {
                System.out.print("\t\t欧阳颖\n"+
                        "\t\t中南大学\n"+
                        "\t\tQQ:16311416\n");
                timeOut(4);
            }break;
        }
        }while (choice != 0);
        System.out.println("Bye! ^-^");
        System.exit(0);
    }
    public String inputData()//从终端接收数据的方法,返回字符串
    throws IOException,NumberFormatException
    {
            System.out.print("请依次输入 :学号 姓名 性别 成绩\n" +
          "每项数据请用空格隔开:");
            String all = "";
        try{
            BufferedReader in =                               //从终
                new BufferedReader (                          //端接
                        new InputStreamReader(System.in));    //收数     
                String inputLine = in.readLine();             //据
                StringTokenizer str =                                           
                    new StringTokenizer(inputLine," ");//接收的数据用空格隔开,这个类用来提取每个字符串                          
                long num = Integer.valueOf(str.nextToken()).longValue();//学号           
                String name = (String)str.nextToken();                  //姓名
                String sex = (String)str.nextToken();                   //性别 
                double mark = Integer.valueOf(str.nextToken()).doubleValue();//分数 
                all = String.valueOf(num) +" , "+
                name +" , "+
                sex +" , "+
                String.valueOf(mark);//把所有的数据用" , "隔开然后在连起来放进字符串all            
        }catch (IOException e){}
         catch (NumberFormatException e){}
        return all;//返回字符串all
    }
    public void addData(String str)//增加数据的方法
    throws IOException
    {
        String s1 ="",s2="" ,s3= "";
        File file = new File("data.txt");
        if (file.exists())//如果文件data.txt存在
        {
        try{
            BufferedReader in =
                new BufferedReader(
                        new FileReader("data.txt"));
            while ((s1=in.readLine())!=null)
                s2+=s1+"\n";//把文件中的每行数据全部放进一个字符串s2                          
            s2+=str+"\n";   //再把s2于形参str相连放进s2
            BufferedReader in2 =                                  //把字符
                new BufferedReader(                               //串s2也 
                        new StringReader(s2));                    //就是原
            PrintWriter out =                                     //文件+
                new PrintWriter(                                  //形参str(新输入的一行数据)
                        new BufferedWriter(                       //重新写进data.txt
                                new FileWriter("data.txt")));     //覆盖原来的数据 
            while ((s3=in2.readLine())!= null)
            {
                out.println(s3);
            }
            out.close();
            //System.out.println("write data true.");
        }catch (IOException e){}
        }else{
            System.err.println("File \"data\" Missing!");
        }
    }
    public void clearData()//清除data.txt的所有数据的方法
    throws IOException
    {
        File file = new File("data.txt");
        if(file.exists())//如果文件在 
        {
            try{
                PrintWriter out = 
                    new PrintWriter(
                            new BufferedWriter(
                                    new FileWriter(file)));
                out.print("");//在文件data.txt里写进一个空字符,所以清除了原来的内容
                out.close();  //关闭文件
                System.out.println("clear data true!");
            }catch(IOException e){}
         }else{
                System.err.println("File \"data\" Missing!");
         }
    }
    public void deleteData(long deleteNumber)//删除某条数据
    throws IOException,FileNotFoundException
    {
        isDelete = true;
        try{
        DataMap mp = new DataMap();//生成一个自己编写的容器
        long j=0;
        String s1="",s2="",s3="";
            BufferedReader in =
                new BufferedReader(
                        new FileReader("data.txt"));
            while ((s1=in.readLine())!=null)
            {
                j=numberTokenizer(s1);
                mp.put(j,s1);
            }
            try{
                if(mp.containsKey( String.valueOf(deleteNumber).toString()))
                {
                    mp.remove(deleteNumber);