Java基础——IO实现文件的增删改查

使用BufferedReader和BufferedWriter实现对文件信息的增删改查

package dao.impl;
    

import dao.IStudentDao;
    
import entity.Student;
    

import java.io.*;
    
import java.util.ArrayList;
    
import java.util.List;


/**
 * @Author: hyy
 * @Date: 2020/12/9 16:55
 */
public class IStudentDaoImpl implements IStudentDao {


    /**
     * 根据id和课程编号进行 选课
     * @param student
     * @return
     * @throws IOException
     */
    @Override
    public boolean insertCourse(Student student) throws IOException {
    
        BufferedWriter bufferedWriter=new BufferedWriter(new FileWriter("UniversitySelectCourseSystem\\SelectCourse.txt",true));
    
        bufferedWriter.write(student.getId()+","+student.getStudentName()+","+student.getCourseName()+","+student.getSerialNumber());
    
        bufferedWriter.newLine();
    
        bufferedWriter.close();
    
        return false;

    }


    /**
     * 根据id和课程编号进行 退课
     * @param id
     * @param serialNumber
     * @return
     * @throws IOException
     */
    @Override
    public boolean deleteCourse(Integer id,String serialNumber) throws IOException {
    
        BufferedReader bufferedReader=new BufferedReader(new FileReader("UniversitySelectCourseSystem\\SelectCourse.txt"));
    
        ListStudent>
     studentList=new ArrayList>
    ();
    
        String string ;

        while ((string=bufferedReader.readLine())!=null){
    
            String[] dates=string.split(",");
    
            Student student=new Student(Integer.parseInt(dates[0]),dates[1],dates[2],dates[3]);
    
            System.out.println(student.toString());
    
            studentList.add(student);

        }
    
        for (int i = 0;
     i  studentList.size();
 i++) {
    
            Student student=studentList.get(i);

            if (student.getSerialNumber().equals(serialNumber)){
    
                studentList.remove(i);

            }

        }
    
        BufferedWriter bufferedWriter=new BufferedWriter(new FileWriter("UniversitySelectCourseSystem\\SelectCourse.txt"));
    
        for (int i = 0;
     i  studentList.size();
 i++) {
    
            Student student=studentList.get(i);
    
            String returnString=String.format("%s,%s,%s,%s",student.getId(),student.getStudentName(),student.getCourseName(),student.getSerialNumber());
    
            bufferedWriter.write(returnString);
    
            bufferedWriter.newLine();

        }
    
        bufferedReader.close();
    
        bufferedWriter.close();
    
        return false;

    }


    /**
     * 根据id 查询已选课程
     * @param id
//     * @param serialNumber
     * @return boolean
     * @throws IOException
     */
    @Override
    public boolean selectCourse(Integer id) throws IOException {
    
       BufferedReader bufferedReader=new BufferedReader(new FileReader("UniversitySelectCourseSystem\\SelectCourse.txt"));
    
       String string;
    
       ListStudent>
     studentList=new ArrayList>
    ();

       while ((string=bufferedReader.readLine())!=null){
    
           String []dates=string.split(",");
    
           Student student=new Student(Integer.parseInt(dates[0]),dates[1],dates[2],dates[3]);
    
           System.out.println(student.toString());
    
           studentList.add(student);

       }
    
        for (int i = 0;
     i  studentList.size();
 i++) {
    
            Student student=studentList.get(i);

            if (student.getId().equals(id)){
    
                System.out.println(student.toString());

            }

        }
    

        return false;

    }

}
    

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