從Java中的.txt讀取對象

Question

我正在嘗試向文件寫入對象，然后從文件中讀取對象並對其執行一些操作。 該對象可以很好地寫入文件，但是當我嘗試從文件中檢索它時，我什么也沒得到。 我使用的代碼如下：

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.Date;


public class Driver 
{
    public static void main(String[] args) throws IOException, ClassNotFoundException 
    {
        FileOutputStream fos = new FileOutputStream("C:\\Users\\Russian\\Desktop\\file.txt");
        ObjectOutputStream oos = new ObjectOutputStream(fos);

        Person person = new Person("B1234","Roshane","Nolan","male","Spanish Town",new Date(),
                "B2134","B3214",150.0,5.11);

        oos.writeObject(person);

        oos.flush();
        oos.close();

        //READING FROM THE FILE

        FileInputStream fis = new FileInputStream("C:\\Users\\Russian\\Desktop\\file.txt");
        ObjectInputStream ois = new ObjectInputStream(fis);


        Person object = (Person) ois.readObject();
        System.out.println(object);

        ois.close();
    }

}

Answer 1

我認為您必須通過從API文檔ObjectInputStream實現java.io.Serializable來序列化Person對象

  ObjectInputStream is used to recover those objects previously serialized. 

下面的代碼（主要功能與您的相同：

  public static void main(String[] args) throws IOException, ClassNotFoundException 
    {
        FileOutputStream fos = new FileOutputStream("src/main/resources/Test.txt");
        ObjectOutputStream oos = new ObjectOutputStream(fos);

        Person person = new Person("B1234","Roshane","Nolan","male","Spanish Town",new Date(),
                "B2134","B3214",150.0,5.11);

        oos.writeObject(person);

        oos.flush();
        oos.close();

        //READING FROM THE FILE

        FileInputStream fis = new FileInputStream("src/main/resources/Test.txt");
        ObjectInputStream ois = new ObjectInputStream(fis);


        Person object = (Person) ois.readObject();
        System.out.println(object.toString());


    }

人類

  import java.util.Date;

  public class Person implements java.io.Serializable{

String arg1,arg2,arg3,arg4,arg5,arg6,arg7;
Double d1,d2;
Date date1;
public Person(String string, String string2, String string3,
        String string4, String string5, Date date, String string6,
        String string7, double d, double e) {
    this.arg1=string;
    this.arg2=string2;
    this.arg3=string3;
    this.arg4=string4;
    this.arg5=string5;
    this.arg6=string6;
    this.arg7=string7;
    this.d1=d;
    this.d2=e;
    this.date1=date;


    // TODO Auto-generated constructor stub
}

@Override
public String toString()
{
    return "Person:"+this.arg1+":"+this.arg2+":"+this.arg3+":"+this.arg4+":"+this.arg5+":"+this.arg6+":"+this.arg7+":"+this.d1+":"+this.d2+":"+this.date1;
}


 }

輸出：

Person:B1234:Roshane:Nolan:male:Spanish Town:B2134:B3214:150.0:5.11:Sun Apr 14 23:11:27 CDT 2013

Answer 2

您應該指定“無”的意思。 你得到：

• 空（永遠不會發生）
• 異常（例如，如果人員類或該類中的字段未實現Serializable）
• 字符串“ somepackage.Person@hashcodenumber”（在這種情況下，您需要重寫Person類中的toString（））
• 沒有設置任何字段的Person對象（請參見下面的答案）
• 任何其他字符串-在Person類中檢查您的'toString'方法

您可以將writeObject和readObject添加到您的人員類。 http://docs.oracle.com/javase/1.4.2/docs/api/java/io/ObjectInputStream.html

private void writeObject(ObjectOutputStream oos) 
{
    // default serialisation 
    oos.defaultWriteObject();

    // write custom fields
    oos.writeUTF(this.name);
}

private void readObject(ObjectInputStream ois) 
           throws ClassNotFoundException, IOException 
    {
    // default serialisation
    ois.defaultReadObject();

    // read custom fields
    this.name = ois.readUTF();
}