学生信息管理系统（序列化与反序列化实现）

深藏阁楼爱情的钟 2023-05-22 08:48 25阅读 0赞

**问题描述**：由于序列化的对象，不能修改属性，序列化一旦保存到文件中就不可修改，并且也不能删除文件中序列化的对象。（这里可以将对象填入到集合或数组中，反序列化到内存，通过对集合的删除操作后，并将其写回文件，可以实现对象的删除)但依然无法真正意义上的删除。因此梦阳辰此次系统的书写，对于删除功能，和修改功能其实是没有实现的，只实现了，增加，查找，和遍历。注意这里没有采用new File的形式，需要自己创建文件。  
对于反序列化输出多个对象存在的问题也许这篇文章能帮到你：  
[Java序列化及反序列化将多个对象追加到文件并读取多个对象（ObjectOutputStream，ObjectInputStream)][Java_ObjectOutputStream_ObjectInputStream]

*  用户类：

//说明：注释代码为new了多次ObjectOutputStream的解决方案。
    public class Teachers { 
        public static void main(String[] args) { 
            Scanner sc = new Scanner(System.in);
            ObjectOutputStream os = null;
            FileOutputStream fileOut=null;
            try { 
                fileOut=new FileOutputStream("src/Day32/StudentsInformation",true);
                os =new ObjectOutputStream(fileOut);
    
            } catch (IOException e) { 
                e.printStackTrace();
            }
            while(true){ 
                System.out.println("========请选择你要进行的操作编号==========");
                System.out.println("\t\t\t添加学生信息(1)\n\t\t\t浏览所有学生信息(2)");
                System.out.println("\t\t\t查找学生信息(3)\n\t\t\t删除学生信息(4)");
                System.out.println("\t\t\t修改学生信息(5)\n\t\t\t退出系统(-1)");
                System.out.println("==========================================\n请选择功能：");
                int flag = sc.nextInt();
                switch (flag){ 
                    case 1:AddInformation(sc,os);break;
                    case 2:
                        try { 
                            ViewInformation();
                        } catch (IOException e) { 
                            e.printStackTrace();
                        } catch (ClassNotFoundException e) { 
                            e.printStackTrace();
                        }
                        break;
                    case 3:
                        try { 
                            FindInformation(sc);
                        } catch (MyException e) { 
                            e.printStackTrace();
                        } catch (IOException e) { 
                            e.printStackTrace();
                        } catch (ClassNotFoundException e) { 
                            e.printStackTrace();
                        }
                        break;
                    case 4:
                        try { 
                            DeleteInformation(sc);
                        } catch (MyException e) { 
                            e.printStackTrace();
                        } catch (IOException e) { 
                            e.printStackTrace();
                        } catch (ClassNotFoundException e) { 
                            e.printStackTrace();
                        }
                        break;
                    case 5:
                        try { 
                            MoidfyInformation(sc);
                        } catch (IOException e) { 
                            e.printStackTrace();
                        } catch (ClassNotFoundException e) { 
                            e.printStackTrace();
                        }
                        break;
                    case -1:sc.close();
                        try { 
                            os.close();//退出系统时关闭os流
                        } catch (IOException e) { 
                            e.printStackTrace();
                        }
                        return;
                    default:
                        System.out.println("The number you entered is wrong,please enter again!");
                }
            }
    
        }
    //Modify
        private static void MoidfyInformation(Scanner sc) throws IOException, ClassNotFoundException { 
            ObjectInputStream ois =null;
            FileInputStream out =new FileInputStream("src/Day32/StudentsInformation") ;
            try { 
                //反序列化
                ois = new ObjectInputStream(out);
            } catch (IOException e) { 
                e.printStackTrace();
            }
    
            Students p=null;
            System.out.println("请输入你要修改的学生学号：");
            int num = sc.nextInt();
            while(out.available()>0){ //代表文件还有内容
                p=(Students)ois.readObject();
                if (p.getNum() == num) { 
                    System.out.println("请输入新的名字：");
                    String name =sc.next();
                    p.setName(name);
                    System.out.println("请输入新的学号：");
                    int num1 = sc.nextInt();
                    p.setNum(num1);
                    System.out.println("请输入性别：");
                    String gender = sc.next();
                    p.setGender(gender);
                    System.out.println("请输入生日：(如：1999-9-10）");
                    String birthday =sc.next();
                    p.setBirthday(birthday);
                    System.out.println("请输入联系方式：");
                    String contactInformation =sc.next();
                    p.setContactInformation(contactInformation);
                    System.out.println("修改成功！");
                }
            }
            if(ois !=null){ 
                ois.close();
            }
    
        }
    //Delete
        private static void DeleteInformation(Scanner sc) throws MyException, IOException, ClassNotFoundException { 
            ObjectInputStream ois =null;
            FileInputStream out =new FileInputStream("src/Day32/StudentsInformation") ;
            try { 
                //反序列化
                ois = new ObjectInputStream(out);
            } catch (IOException e) { 
                e.printStackTrace();
            }
            Students p=null;
            System.out.println("请输入你要删除的学生学号：");
            int num = sc.nextInt();
            while(out.available()>0){ //代表文件还有内容
                p=(Students)ois.readObject();
                if (p.getNum() == num) { 
                    p.setName(null);
                    p.setNum(0);
                    p.setGender(null);
                    p.setBirthday(null);
                    p.setContactInformation(null);
                    System.out.println("删除成功！");
                }
            }
            if(ois!=null){ 
                ois.close();
            }
        }
    //Find
        private static void FindInformation(Scanner sc,int...args) throws MyException, IOException, ClassNotFoundException { //可变长度参数
            ObjectInputStream ois = null;
            FileInputStream out = new FileInputStream("src/Day32/StudentsInformation");
            try { 
                //反序列化
                ois = new ObjectInputStream(out);
            } catch (IOException e) { 
                e.printStackTrace();
            }
            Students p = null;
            System.out.println("请输入你要查找的学生学号：");
            int num = sc.nextInt();
            while (out.available() > 0) { //代表文件还有内容
                p = (Students) ois.readObject();
                if (num == p.getNum()) { 
                    System.out.println(p);
                }
            }
            ois.close();
        }
    //ViewAllInformation
        private static void ViewInformation() throws IOException, ClassNotFoundException { 
            ObjectInputStream ois =null;
            FileInputStream out =new FileInputStream("src/Day32/StudentsInformation") ;
            try { 
                //反序列化
                ois = new ObjectInputStream(out);
            } catch (IOException e) { 
                e.printStackTrace();
            }
            Students p=null;
           /* p=(Students)ois.readObject();//从流中读取对象,需要进行强转 System.out.println(p);*/
            while(out.available()>0){ //代表文件还有内容
                /*byte[] buf =new byte[4]; out.read(buf);//取走头部，不做处理*/
                p=(Students)ois.readObject();   //读取第二个对象
                System.out.println(p);
            }
            try { 
                ois.close();
            } catch (IOException e) { 
                e.printStackTrace();
            }
    
        }
    
    //Add
        private static void AddInformation(Scanner sc,ObjectOutputStream os) { 
    
           /* ObjectOutputStream os = null; FileOutputStream fileOut=null; try { fileOut=new FileOutputStream("src/Day32/StudentsInformation",true); //序列化,只能实例化一个对象流，不然添加的时候就保存到不同的地方了 os =new ObjectOutputStream(fileOut); } catch (IOException e) { e.printStackTrace(); }*/
            System.out.println("请输入名字：");
            String name =sc.next();
            System.out.println("请输入学号：");
            int num = sc.nextInt();
            //如果要添加的学号学号存在，抛异常，提醒用户
            try { 
                IsExist(num);
            } catch (IOException e) { 
                e.printStackTrace();
            } catch (ClassNotFoundException e) { 
                e.printStackTrace();
            } catch (MyException e) { 
                e.printStackTrace();
                return;//出现异常，退出方法
            }
            System.out.println("请输入性别：");
            String gender = sc.next();
            System.out.println("请输入生日：(如：1999-9-10）");
            String birthday =sc.next();
            System.out.println("请输入联系方式：");
            String contactInformation =sc.next();
            Students a =new Students(name,num,gender,birthday,contactInformation);
            try { 
                os.writeObject(a);
                os.flush();
            } catch (IOException e) { 
                e.printStackTrace();
            }
            /*finally { if(os!=null){ try { os.close(); } catch (IOException e) { e.printStackTrace(); } } }*/
        }
        //判断是否已经存在该学号
        private static void IsExist(int num) throws IOException, ClassNotFoundException, MyException { 
            ObjectInputStream ois = null;
            FileInputStream out = new FileInputStream("src/Day32/StudentsInformation");
            try { 
                //反序列化
                ois = new ObjectInputStream(out);
            } catch (IOException e) { 
                e.printStackTrace();
            }
            Students p = null;
            while (out.available() > 0) { //代表文件还有内容
                p = (Students) ois.readObject();
                if (num == p.getNum()) { 
                    throw new MyException("学号已存在！");//注意抛了异常就不会执行下面代码了，所以不用return
                }
            }
            ois.close();
        }
    }

*  学生类：

public class Students implements Serializable { 
        private static final long serizlVersionUID=646646465464646546L;
        private  String name;
        private int num;//学号
        private  String gender;//性别
        private String birthday;//生日
        private String ContactInformation;//联系方法
        //构造方法
        public Students() { 
        }
    
        public Students(String name, int num, String gender, String birthday, String contactInformation) { 
            this.name = name;
            this.num = num;
            this.gender = gender;
            this.birthday = birthday;
            ContactInformation = contactInformation;
        }
    
        public static long getSerizlVersionUID() { 
            return serizlVersionUID;
        }
    
        public String getName() { 
            return name;
        }
    
        public void setName(String name) { 
            this.name = name;
        }
    
        public int getNum() { 
            return num;
        }
    
        public void setNum(int num) { 
            this.num = num;
        }
    
        public String getGender() { 
            return gender;
        }
    
        public void setGender(String gender) { 
            this.gender = gender;
        }
    
        public String getBirthday() { 
            return birthday;
        }
    
        public void setBirthday(String birthday) { 
            this.birthday = birthday;
        }
    
        public String getContactInformation() { 
            return ContactInformation;
        }
    
        public void setContactInformation(String contactInformation) { 
            ContactInformation = contactInformation;
        }
    
        @Override
        public String toString() { 
            return "Students{" +
                    "name='" + name + '\'' +
                    ", num=" + num +
                    ", gender='" + gender + '\'' +
                    ", birthday=" + birthday +
                    ", ContactInformation='" + ContactInformation + '\'' +
                    '}';
        }
    }

*  自定义异常类：

public class MyException extends Exception { 
        public MyException() { 
        }
    
        public MyException(String message) { 
            super(message);
        }
    }

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[Java_ObjectOutputStream_ObjectInputStream]: https://editor.csdn.net/md/?articleId=105559966
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