Java Io 实现增删改查

insertUserDao

@Override
    public boolean insertUserDao(User user) {
        try {
            BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter("TrainSystem\\User.txt",true));
            String returnString=String.format("%s,%s,%s",user.getId(),user.getUserName(),user.getPassword());
            bufferedWriter.write(returnString);
            bufferedWriter.newLine();
            bufferedWriter.close();
            return true;
        }catch (Exception e){
            System.out.println("文件增加失败");
            return false;
        }
    }

deleteUserDao

 @Override
    public boolean deleteUserDao(Integer id) {
        try{
            BufferedReader bufferedReader = new BufferedReader(new FileReader("TrainSystem\\User.txt"));
            List<User> userList=new ArrayList<>();
            String string;
            while ((string=bufferedReader.readLine())!=null){
                String[] dates=string.split(",");
                User user=new User(Integer.parseInt(dates[0]),dates[1],dates[2]);
                userList.add(user);
            }
            for (int i = 0; i <=userList.size()-1 ; i++) {
                User user=userList.get(i);
                if (user.getId().equals(id)){
                    userList.remove(i);
                }
            }
            BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter("TrainSystem\\User.txt"));
            for (int i = 0; i <userList.size() ; i++) {
                User user=userList.get(i);
                String returnString=String.format("%s,%s,%s",user.getId(),user.getUserName(),user.getPassword());
                bufferedWriter.write(returnString);
                bufferedWriter.newLine();
            }
            bufferedReader.close();
            bufferedWriter.close();
            return true;
        }catch (Exception e){
            System.out.println("数据删除失败");
            return false;
        }
    }

updateUserDao

@Override
    public boolean updateUserDao(User user, Integer id) {
        try{
            BufferedReader bufferedReader = new BufferedReader(new FileReader("TrainSystem\\User.txt"));
            List<User> userList=new ArrayList<>();
            String string;
            while ((string=bufferedReader.readLine())!=null){
                String[] dates=string.split(",");
                User returnUser=new User(Integer.parseInt(dates[0]),dates[1],dates[2]);
                System.out.println(returnUser);
                userList.add(returnUser);
            }
            for (int i = 0; i <=userList.size()-1 ; i++) {
                User returnUser=userList.get(i);
                if (returnUser.getId().equals(id)){
                    userList.set(i,user);
                }
            }
            BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter("TrainSystem\\User.txt"));
            for (int i = 0; i <userList.size() ; i++) {
                User returnUser=userList.get(i);
                String returnString=String.format("%s,%s,%s",returnUser.getId(),returnUser.getUserName(),returnUser.getPassword());
                bufferedWriter.write(returnString);
                bufferedWriter.newLine();
            }
            bufferedReader.close();
            bufferedWriter.close();
            return true;
        }catch (Exception e){
            System.out.println("数据更新失败");
            return false;
        }

    }

selectUserDao

 @Override
    public List<User> selectUserDao() {
        try {
            BufferedReader bufferedReader = new BufferedReader(new FileReader("TrainSystem\\User.txt"));
            String string;
            List<User> userList = new ArrayList<>();
            while ((string = bufferedReader.readLine()) != null) {
                String[] dates = string.split(",");
                User user = new User(Integer.parseInt(dates[0]), dates[1], dates[2]);
                userList.add(user);
            }
            bufferedReader.close();
            return userList;
        } catch (Exception e) {
            System.out.println("数据查询失败");
            return null;
        }
    }