Question

我想读取和写入文件的对象。这是我的尝试：

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;

public class SaveOpen implements Serializable 
{
    private static String fileName;
    private ArrayList<Person> list = new ArrayList<Person>();

    public SaveOpen() {
        fileName = "file.txt";
    }
    //Reader
    public static Object deserialize() throws IOException,
    ClassNotFoundException {
        FileInputStream fis = new FileInputStream(fileName);
        BufferedInputStream bis = new BufferedInputStream(fis);
        ObjectInputStream ois = new ObjectInputStream(bis);
        Object obj = ois.readObject();
        ois.close();
        return obj; 
    }
    //Writer
    public static void serialize(Object obj)
            throws IOException {
        FileOutputStream fos = new FileOutputStream(fileName);
        BufferedOutputStream bos = new BufferedOutputStream(fos);
        ObjectOutputStream oos = new ObjectOutputStream(bos);
        oos.writeObject(obj);
        oos.close();
    }
    public void setFileName(String fileName) {
        this.fileName = fileName;
    }
    public ArrayList<Person> getListPersons() {
        return list;
    }

}

但是，我不知道这是否是正确的方法，也不知道如何在课堂上实现这一点。对象是Person，我想从文件中保存并读取该对象。应该对.txt文件进行吗？谁可以澄清事情？谢谢！

Answer 1

如果您希望文件是人类可读的，我建议将其保存为xml。

示例：

对象类

import java.io.Serializable;

public class Person implements Serializable
{
     private String username;
     private int    id;

     public String UserName() { return username; }
     public void setUserName(String str) { username = str;} 

     public int ID() { return id; }
     public void setID(int ID) { id = ID; }    
}

-Serializer /解串器

import Settings.Person;
import java.beans.XMLDecoder;
import java.beans.XMLEncoder;
import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;

public class XmlSerializer 
{
    //File path to serialize to and deserialize from
    private static final String SERIALIZED_FILE_NAME = "yourSavePath.xml";
    //Insert person object and save as xml file to chosen filepath
    public static void Serialize(Person person)
    {
        try
        {
            FileOutputStream    os = new FileOutputStream(SERIALIZED_FILE_NAME);
            XMLEncoder          encoder = new XMLEncoder(os);
                                encoder.writeObject(person);
                                encoder.close();
        }
        catch(FileNotFoundException ex)
        {
            System.out.println(ex.getMessage());
        }
    }
    //Deserialize xml file into person object
    public static Person Deserialize()
    {
        try
        {
            FileInputStream os = new FileInputStream(SERIALIZED_FILE_NAME);
            XMLDecoder decoder = new XMLDecoder(os);
            Person p = (Person)decoder.readObject();
            decoder.close();
            return p;
        }
        catch(FileNotFoundException ex)
        {
            System.out.println(ex.getMessage());
        }
        return null;
    }
  }

Answer 2

你已经做对了。您可以在txt文件中保护对象，尽管它没有多大意义，我宁愿使用二进制文件。

要将多个对象存储在单个文件中，只需将它们打包在Collection中，然后序列化Collection对象即可。

从文件中读取对象时，通过instanceof检查其类，并将其转换为任何类型。

在文件中写入和读取对象

2 个答案: