1) Implement three basic functions: login, registration, and lottery.
2) Login: The user enters the account and password to log in. After entering the account, it will match the registered user. If the entered user does not exist, exit. There are three opportunities to enter the password. After successful login, the main interface will display the account of the logged in user. information.
3) Registration: The user first enters the account name. The system checks whether the name exists. If it exists, the user is asked to change the name. Otherwise, enter the password. The password requires a 6-digit string. After successful registration, the system randomly assigns a A four-digit ID number that is unique from existing users.
4) Lottery: Prerequisite for function implementation: The user must be logged in. When this prerequisite is met, the system randomly selects 5 different users from existing users and marks them as lucky users, and determines whether the logged-in user has been selected.
5) Data storage: Use the file system, import the java.io.* package,
6) Data structure: Login user information is stored in ArrayList, lucky user number and id are stored in HasMap
1) Login: 
2) Registration: 
3) Lottery: 
运行代码之前务必在user.txt中创建五个以上的用户。
import java.util.Scanner;import java.util.ArrayList;import java.io.*;import java.util.StringTokenizer;public class Dos {
static boolean logined=false;
public static void main(String[] args) {
User user=new User();
int k=0;
while( (k=Main(user))>=1&&k<5){
switch (k){
case 1:
System.out.print((k=user.login(user))==-1?"此用户不存在!\n":"");
System.out.print((k==-2)?"===<<警告>>用户：["+user.userName+"]已处于登录状态，无需重复登录！\n":"");
break;
case 2:
user.regist();
break;
case 3:
user.getLuckly();
break;
default:System.exit(0);
}
}
}
static int Main(User user){
System.out.println("**********************************************");
System.out.println("********************主菜单********************");
System.out.println("**********************************************");
System.out.println("****** <1> 登 录 ******");
System.out.println("****** <2> 注 册 ******");
System.out.println("****** <3> 抽 奖 ******");
System.out.println("****** <4> 退 出 ******");
System.out.println("**********************************************");
System.out.println("==============================================");
System.out.println(logined ? "-[已登录]- （1）用户名:"+user.userName+" （2）用户账号:"+user.userId:"-[未登录]- （1）用户名:NaN （2）用户账号:NaN");
System.out.println("==============================================");
System.out.print("###===>请输入您的选择：");
return (new Scanner(System.in)).nextInt();
}}public class User{
String userName,userId,userPwd;
public User(){}
public User(String userName, String userId, String userPwd) {
this.userName = userName;
this.userId = userId;
this.userPwd = userPwd;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
if(!userName.equals("")) {
ArrayList<String> temp;
this.userId=(temp=(new operatorFile(this.userName = userName)).getUserMess(0)).get(1);
this.userPwd=temp.get(2);
}
}
public String getUserId() {
return userId;
}
public String setUserId() {
String userId="";
while((new operatorFile(userId=String.valueOf ((int) (Math.random()*9000+1000)))).getUserMess(1).size()>0){ }
return (this.userId = userId);
}
public String getUserPwd() {
return userPwd;
}
public int login(User u) {
int inputTimes=3;
Scanner scanner=new Scanner(System.in);
operatorFile getUserMessage=new operatorFile();
System.out.print("======>请输入您的用户名：");
String uName="";
getUserMessage.setUser(uName=scanner.nextLine());
ArrayList<String> userMess=getUserMessage.getUserMess(0);
if(userMess.size()<1) return -1;//返回-1表示用户不存在
if (uName.equals(userName)) return -2;//返回-2表示用户重复登录
System.out.print("======>请输入您的登录密码：");
while(!scanner.next().equals(userMess.get(2))&&inputTimes>0)
System.out.print("===>密码输入错误！"+((--inputTimes)>0?"您还剩"+inputTimes+"次机会！":"三次机会已经用完了！输入任意退出"));
System.out.println(inputTimes>0?"==>登录成功！您本次输入密码"+(4-inputTimes)+"次！":"==>登录失败！");
setUserName(inputTimes>0?uName:"");
Dos.logined=inputTimes>0?true:false;
return 0;
}
public void regist() {
User u=new User();
Scanner scanner=new Scanner(System.in);
System.out.print("===>请输入新的用户名：");
String name;
while(new operatorFile(name=scanner.nextLine()).getUserMess(0).size() > 0)
System.out.print("已存在此用户,注册失败！\n===>请重新输入新的用户名：");
System.out.print("======>请设置您的(六位数字)登录密码：");
String regex = "[0-9]{6}", pwd;
while (!(pwd = scanner.nextLine()).matches(regex))
System.out.print("==>密码格式不正确，请重新设置您的(六位数字)登录密码：");
System.out.println("已为用户： "+(u.userName=name)+" 生成唯一ID: "+(u.userPwd=pwd));
(new operatorFile()).writeUserMess(u);
System.out.println("=======>注册成功！");
}
public static HashMap<String,String> lucklyUsers=new HashMap<>();
public void getLuckly() {
if (!Dos.logined) {
System.out.println("===>警告：没有用户登录，无法抽奖！");
return ;
}
while(lucklyUsers.size()<5)
{
String id="";
ArrayList<String> u;
while((u=(new operatorFile(id=String.valueOf ((int) (Math.random()*9000+1000)))).getUserMess(1)).size()<1){ }
lucklyUsers.put(u.get(1),u.get(0));
}
Iterator iterator=lucklyUsers.entrySet().iterator();
int no=1;
boolean LUCKLY=false;
System.out.println("====>恭喜以下用户获得幸运称号：");
while(iterator.hasNext()){
Map.Entry entry=(Map.Entry) iterator.next();
System.out.println("幸运用户["+(no++)+"] 用户名："+entry.getValue()+" 用户编号："+entry.getKey());
LUCKLY = entry.getKey().equals(this.userId) ? true : LUCKLY;
}
System.out.println(LUCKLY?"=========>恭喜您在本次抽奖中获得幸运称号！":"=========>很遗憾，今日您未获奖 ！-_-！");
}
public String toString(){
return this.userName+" "+this.userId+" "+this.userPwd;
}}public class operatorFile {
String user;
public void setUser(String user) {
this.user = user;
}
public operatorFile(String user) {
this.user = user;
}
public operatorFile() { }
public ArrayList<String> getUserMess(int index){
ArrayList<String> temp=new ArrayList<String>();
File file=new File("user.txt");
String line="";
try{
BufferedReader br=new BufferedReader(new FileReader(file));
while ((line = br.readLine())!=null && line!="\n"){
temp.clear();
StringTokenizer sk=new StringTokenizer(line);
while (sk.hasMoreTokens()) {
temp.add(sk.nextToken());
}
if (temp.get(index).equals(this.user)) break;
}
}
catch(IOException e){}
return (line==null)?new ArrayList<String>():temp;
}
public void writeUserMess(User u){
try{
BufferedWriter bw=new BufferedWriter(new FileWriter(new File("user.txt"),true));
bw.write(u.toString()+"\n");
bw.close();
}
catch (IOException e){ }
}}##JAVA Implementation of User LotteryRequirements Analysis1) Implement three basic functions: login, registration, and lottery.
2) Login: The user enters the account and password to log in. After entering the account, it will match the registered user. If the entered user does not exist, exit. There are three opportunities to enter the password. After successful login, the main interface will display the account of the logged in user. information.
3) Registration: The user first enters the account name. The system checks whether the name exists. If it exists, the user is asked to change the name. Otherwise, enter the password. The password requires a 6-digit string. After successful registration, the system randomly assigns a A four-digit ID number that is unique from existing users.
4) Lottery: Prerequisite for function implementation: The user must be logged in. When this prerequisite is met, the system randomly selects 5 different users from existing users and marks them as lucky users, and determines whether the logged-in user has been selected.
5) Data storage: Use the file system, import the java.io.* package,
6) Data structure: Login user information is stored in ArrayList, lucky user number and id are stored in HasMap
2) Registration:
3) Lottery:
运行代码之前务必在user.txt中创建五个以上的用户。
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