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

代码语言：javascript复制

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"));
        List<Student> 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;
       List<Student> 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;
    }
}

java bufferedreader io 基础

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