實(shí)現(xiàn)一個(gè)登錄注冊功能
把注冊成功的用戶信息寫入到硬盤中

package com.wxhl.jq0802;
import java.io.*;
import java.util.HashSet;
import java.util.Scanner;

class User{
    String name;
    String passwd;
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPasswd() {
        return passwd;
    }

    public void setPasswd(String passwd) {
        this.passwd = passwd;
    }

    public User(String name,String passwd){
        this.name = name;
        this.passwd = passwd;
    }
    
    @Override
    public int hashCode() {
        return this.name.hashCode();
    }
    
    @Override
    public boolean equals(Object obj) {
        User user = (User)obj;
        return (user.name.equals(this.name));
    }
}

public class Demo01 {
    
    static HashSet<User> set = new HashSet <User>();
    static File userFile = new File(System.getProperty("user.home")+"/Desktop/user.txt");
    
    public static void main(String[] args) throws IOException {
        readFromFile();
        while(true){
            System.out.println("請選擇功能");
            System.out.println("1.登錄 2.注冊 3.退出");
            int sel = new Scanner(System.in).nextInt();
            switch(sel){
            case 1:
                login();
                break;
            case 2:
                register();
                break;
            case 3:
                exit();
                break;
            default:
                System.out.println("沒有改該選項(xiàng),請重新選擇");
                break;
            }
            
        }
    }
    
    /**
     * 登錄*/
    public static void login(){
        System.out.println("用戶名:");
        String name = new Scanner(System.in).nextLine();
        System.out.println("密碼:");
        String passwd = new Scanner(System.in).nextLine();
        for(User user :set){
            if(user.getName().equals(name) ){
                if(user.getPasswd().equals(passwd)){
                    System.out.println("登錄成功");
                    return;
                }
                else{
                    System.out.println("密碼錯誤");
                    return;
                }
            }
        }
        System.out.println("用戶不存在");
    }
    
    /**
     * 注冊*/
    public static void register (){
        while(true){
            System.out.println("請輸入以下信息:");
            System.out.println("用戶名:");
            String name = new Scanner(System.in).nextLine();
            System.out.println("密碼:");
            String passwd = new Scanner(System.in).nextLine();
            
            if(set.add(new User(name,passwd))){
                System.out.println("注冊成功");
                break;
            }else{
                System.out.println("用戶名已存在");
            }
        }
    }
    
    /**
     * 從文件中讀取數(shù)據(jù)*/
    public static void readFromFile() throws IOException{
        BufferedReader bufReader = new BufferedReader(new FileReader(userFile));
        String content = null;
        while((content=bufReader.readLine())!=null){
            String str[] = content.split(" ");
            set.add(new User(str[0],str[1]));
        }
        bufReader.close();
    }
    
    /**
     * 退出程序*/
    public static void exit() throws IOException {
        BufferedWriter bufWriter = new BufferedWriter(new FileWriter(userFile,true));
        
        for(User user :set){
            String name = user.getName();
            String passwd = user.getPasswd();
            String str = name+" "+passwd;
            bufWriter.write(str);
            bufWriter.newLine();
        }
        bufWriter.close();
        System.exit(0);
    }
}