IO流训练

一、代码展示

1.Dao包

1.1用户注册

 //用户的注册
    public static boolean userRegister(String username, String psw) {
        FileReader fr = null;
        //创建字符输出流对象 
        FileWriter fw = null;
        //创建字符缓冲输入流对象 
        BufferedReader br = null;
        //创建字符缓冲流输出流对象 
        BufferedWriter bw = null;
        //判断username和密码是否已经存在
        boolean isNameExits = false;
        boolean isPswExits = false;
        //判断是否已经有一个账户被注册
        boolean isUserRegister = false;
        //判断是否注册成功
        boolean isRegisterExcessful = false;
        try {
            String path = "D:\\code\\skshw\\src\\user.txt";
            fr = new FileReader(path);
            fw = new FileWriter(path, true);
            br = new BufferedReader(fr);
            bw = new BufferedWriter(fw);
            //临时变量，存储文档的每行内容
            String temp = "";
            //获取用户名 在文本第一行！
            while ((temp = br.readLine()) != null) {
                if (temp != null) {
                    isUserRegister = true;
                }

                if (temp.equals("username=" + username)) {
                    //判断用户名和密码是否已存在
                    isNameExits = true;
                }
            }

            if (isNameExits == false && isUserRegister == false) {
                //如果文档为空且用户名不存在，则注册用户名和密码
                bw.write("username=" + username);
                bw.newLine();
                bw.write("password=" + psw);
                bw.flush();
                isRegisterExcessful = true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (br != null) {
                    br.close();
                }
                if (fw != null) {
                    fw.close();
                }
                if (fr != null) {
                    fr.close();
                }
                if (bw != null) {
                    bw.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        //如果用户名已经存在，返回false
        if (isNameExits) {
            return false;
        }
        return isRegisterExcessful;
    }

1.2用户登录

 //用户登录
    public static boolean userLogin(String username, String psw) {
        boolean rst = false;
        BufferedReader br = null;
        String line = null;
        boolean uB = false;
        boolean pB = false;
        try {
            FileReader fr = new FileReader("D:\\code\\skshw\\src\\user.txt");
            br = new BufferedReader(fr);
            //br = new BufferedReader(new FileReader("D:\\code\\skshw\\src\\user.txt"));
            while ((line = br.readLine()) != null) {
                if (line.equals("username=" + username)) {
                    uB = true;
                }
                if (line.equals("password=" + psw)) {
                    pB = true;
                }
            }
            if (uB && pB) {
                rst = true;
            }
            br.close();
            fr.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return rst;
    }

1.3修改密码

 public static boolean userChangePsw(String oldPsw, String newPsw) {
        RandomAccessFile raf = null;
        FileWriter fw = null;
        boolean isOldPsw = false;//是否和原密码一致
        boolean isChangedPsw = false;//是否修改成功
        try {
            String path = "D:\\code\\skshw\\src\\user.txt";
            raf = new RandomAccessFile(path, "r");
            String firstR = raf.readLine();//读取txt第一行
            String temp = "";
            while ((temp = raf.readLine()) != null) {
                if (temp.equals("password=" + oldPsw)) {
                    isOldPsw = true;
                }
            }
            if (isOldPsw) {
                //如果和原密码一致则修改新密码
                fw = new FileWriter(path);
                fw.write(firstR);
                fw.write("\r\n");
                fw.write("password=" + newPsw);
                fw.flush();
                isChangedPsw = true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (raf != null)
                    raf.close();
                if (fw != null)
                    fw.close();
            } catch (Exception e) {
                e.printStackTrace();
            }

        }
        return false;
    }

1.4用户注销（删除用户）

  //注销
    public static boolean userDelete() {
        FileReader fr = null;
        FileWriter fw = null;
        boolean isDeleted = false;
        try {
            String path = "D:\\code\\skshw\\src\\user.txt";
            fr = new FileReader(path);
            int temp = 0;
            if ((temp = fr.read()) != -1) {
                //清空文件内容，因为FileWrite默认是覆盖内容的
                fw = new FileWriter(path);
                isDeleted = true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (fr != null) {
                    fr.close();
                }
                if (fw != null) {
                    fw.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return isDeleted;
    }
}

1.5Dao整体代码

package Dao;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.RandomAccessFile;

/*
*
* 对文档进行操作获取并实现修改密码和用户名等操作
*/
public class UserDao {
    //用户的注册
    public static boolean userRegister(String username, String psw) {
        FileReader fr = null;
        //创建字符输出流对象
        FileWriter fw = null;
        //创建字符缓冲输入流对象
        BufferedReader br = null;
        //创建字符缓冲流输出流对象
        BufferedWriter bw = null;
        //判断username和密码是否已经存在
        boolean isNameExits = false;
        boolean isPswExits = false;
        //判断是否已经有一个账户被注册
        boolean isUserRegister = false;
        //判断是否注册成功
        boolean isRegisterExcessful = false;
        try {
            String path = "D:\\code\\skshw\\src\\user.txt";
            fr = new FileReader(path);
            fw = new FileWriter(path, true);
            br = new BufferedReader(fr);
            bw = new BufferedWriter(fw);
            //临时变量，存储文档的每行内容
            String temp = "";
            //获取第一行用户名
            while ((temp = br.readLine()) != null) {
                if (temp != null) {
                    isUserRegister = true;
                }

                if (temp.equals("username=" + username)) {
                    //判断用户名和密码是否已经存在
                    isNameExits = true;
                }
            }

            if (isNameExits == false && isUserRegister == false) {
                //如果文档为空且用户名不存在，则注册用户名和密码
                bw.write("username=" + username);
                bw.newLine();
                bw.write("password=" + psw);
                bw.flush();
                isRegisterExcessful = true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (br != null) {
                    br.close();
                }
                if (fw != null) {
                    fw.close();
                }
                if (fr != null) {
                    fr.close();
                }
                if (bw != null) {
                    bw.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        //如果用户名已经存在，返回false
        if (isNameExits) {
            return false;
        }
        return isRegisterExcessful;
    }

    //用户登录
    public static boolean userLogin(String username, String psw) {
        boolean rst = false;
        BufferedReader br = null;
        String line = null;
        boolean uB = false;
        boolean pB = false;
        try {
            FileReader fr = new FileReader("D:\\code\\skshw\\src\\user.txt");
            br = new BufferedReader(fr);
            //br = new BufferedReader(new FileReader("D:\\code\\skshw\\src\\user.txt"));
            while ((line = br.readLine()) != null) {
                if (line.equals("username=" + username)) {
                    uB = true;
                }
                if (line.equals("password=" + psw)) {
                    pB = true;
                }
            }
            if (uB && pB) {
                rst = true;
            }
            br.close();
            fr.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return rst;
    }

    //修改密码
    public static boolean userChangePsw(String oldPsw, String newPsw) {
        RandomAccessFile raf = null;
        FileWriter fw = null;
        boolean isOldPsw = false;//是否和原密码一致
        boolean isChangedPsw = false;//是否修改成功
        try {
            String path = "D:\\code\\skshw\\src\\user.txt";
            raf = new RandomAccessFile(path, "r");
            String firstR = raf.readLine();//读取txt第一行
            String temp = "";
            while ((temp = raf.readLine()) != null) {
                if (temp.equals("password=" + oldPsw)) {
                    isOldPsw = true;
                }
            }
            if (isOldPsw) {
                //如果和原密码一致则修改新密码
                fw = new FileWriter(path);
                fw.write(firstR);
                fw.write("\r\n");
                fw.write("password=" + newPsw);
                fw.flush();
                isChangedPsw = true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (raf != null)
                    raf.close();
                if (fw != null)
                    fw.close();
            } catch (Exception e) {
                e.printStackTrace();
            }

        }
        return false;
    }

    //注销
    public static boolean userDelete() {
        FileReader fr = null;
        FileWriter fw = null;
        boolean isDeleted = false;
        try {
            String path = "D:\\code\\skshw\\src\\user.txt";
            fr = new FileReader(path);
            int temp = 0;
            if ((temp = fr.read()) != -1) {
                //清空文件内容，因为FileWrite默认是覆盖内容的
                fw = new FileWriter(path);
                isDeleted = true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (fr != null) {
                    fr.close();
                }
                if (fw != null) {
                    fw.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return isDeleted;
    }
}

2.Servlet包

2.1Main方法

 public static void main(String[] args) {
        UserServlet userServlet = new UserServlet();
        boolean check = true;
        do {
            menu();
            System.out.println("please input choice");
            Scanner scanner = new Scanner(System.in);
            int choice = scanner.nextInt();
            switch (choice)
            {
                case 1:
                    register();
                    break;
                case 2:
                    login();
                    break;
                case 3:
                    userChangePsw();
                    break;
                case 4:
                    userDelete();
                    break;
                case 0:
                    check = false;
                    break;
            }
        }while (check);

    }//用菜单的形式调用其他函数实现用户注册、登录、修改密码和注销的功能

2.2调用的整体代码

package servlet;

import Dao.UserDao;
import java.util.Scanner;
/*
调用Dao中的方法实现功能

*/
public class UserServlet {
    public static void main(String[] args) {
        UserServlet userServlet = new UserServlet();
        boolean check = true;
        do {
            menu();
            System.out.println("please input choice");
            Scanner scanner = new Scanner(System.in);
            int choice = scanner.nextInt();
            switch (choice)
            {
                case 1:
                    register();
                    break;
                case 2:
                    login();
                    break;
                case 3:
                    userChangePsw();
                    break;
                case 4:
                    userDelete();
                    break;
                case 0:
                    check = false;
                    break;
            }
        }while (check);

    }

    public static void register() {
        //注册新用户
        String username = "";
        String password = "";
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入注册用户名：");
        username = scanner.nextLine();
        System.out.println("请输入注册的密码");
        password = scanner.nextLine();
        if (UserDao.userRegister(username, password)) {
            System.out.println("注册成功");
        } else {
            System.out.println("注册失败");
        }
        System.out.println("----------------");
    }


    public static boolean login() {
        //用户登录
        boolean rst = false;
        String userName = null;
        String psw = null;
        UserDao userDao = new UserDao();
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入用户名:");
        userName = scanner.nextLine();
        System.out.println("请输入密码:");
        psw = scanner.nextLine();
        if (UserDao.userLogin(userName,psw)) {
            System.out.println("成功登录!");
        } else {
            System.out.println("登录失败，请重新输入!");
        }
        //校验用户名密码
        rst = userDao.userLogin(userName, psw);
        return rst;
    }

    public static void userChangePsw() {
        //修改密码
        String oldPsw = "";
        String newPsw1 = "";
        String newPsw2 = "";
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入原始密码:");
        oldPsw = scanner.nextLine();
        System.out.println("请输入新的密码!");
        newPsw1 = scanner.nextLine();
        System.out.println("请再次输入!");
        newPsw2 = scanner.nextLine();
        if (newPsw2.equals(newPsw1)) {
            if (UserDao.userChangePsw(oldPsw, newPsw2)) {
                System.out.println("修改失败!");
            } else {
                System.out.println("您已经成功修改密码!");
            }
        } else {
            System.out.println("修改失败,请保持两次密码一致!");
        }
        System.out.println("----------------");
    }

    public static void userDelete() {
        if (UserDao.userDelete()) {
            System.out.println("成功注销！");
        } else {
            System.out.println("注销失败！");
        }
        System.out.println("---------------");
    }

    static void menu(){
        System.out.println("----1:注册新用户------");
        System.out.println("----2:用户登录-------");
        System.out.println("----3:修改用户密码----");
        System.out.println("----4:用户注销-------");
        System.out.println("----0:退出菜单----");
    }
}

二、功能演示

IO流基本实现