java - 无法反序列化所有对象的 ArrayList - 仅反序列化第一个对象

Question

有很多java序列化/反序列化问题，但我找不到问题的答案。我运行 GUI，三个音乐对象在运行时存储在 ArrayList 中(预编码):

private ArrayList<Music> musicList = new ArrayList<Music>();
...
musicList.add(new Music("Metallica", "Master of Puppets"));

然后我从 GUI 添加更多音乐。这些新对象也会添加到 ArrayList musicList 中(我可以通过循环 musicList 来验证这一点)。 然后我可以序列化这个 ArrayList，用记事本打开music.ser 文件并查看其中的所有对象。但我找不到一种方法来反序列化所有这些对象 - 反序列化后我得到的只是那些在运行时添加的对象加上从 GUI 添加的第一个对象。从 GUI 添加的其他对象永远不会反序列化。我不知道是否应该使用循环或缓冲区检查 music.ser 文件(我发现了类似的建议)？任何帮助将不胜感激。以下是我认为对于该问题很重要的代码行:

private ArrayList<Music> musicList;

...

musicList = new ArrayList<Music>();
musicList.add(new Music("Metallica", "Master of Puppets"));
musicList.add(new Music("Pantera", "Far Beyond Driven"));
musicList.add(new Music("Kognitif", "Soul Food"));

...

// serialization method
try {
    FileOutputStream fos = new FileOutputStream("music.ser", true);
    ObjectOutputStream oos = new ObjectOutputStream(fos);
    oos.writeObject(musicList);
    oos.close();
    fos.close();
    for (Music m : musicList) {
        System.out.println("AddMusic: " + m);
    }
} catch (IOException ioe) {
    ioe.printStackTrace();
}

// deserialization method
ArrayList<Music> musicList2 = new ArrayList<Music>();
try {
    FileInputStream fis = new FileInputStream("music.ser");
    ObjectInputStream ois = new ObjectInputStream(fis);
    musicList2 = (ArrayList<Music>) ois.readObject();
    ois.close();
    fis.close();                
    for (Music m : musicList2) {
        System.out.println("Reading Music: \n" + m.getArtist() + " - " + m.getAlbum());
    }               

    }
} catch (Exception ex) {
    ex.printStackTrace();
}

这是 Music.java 类(尽管我认为应该假设这个类已正确编码):

public class Music implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private String artist;
    private String album;
    JTextArea textArea;

    public Music(String artist, String album) {
        super();
        this.artist = artist;
        this.album = album;
    }

    public String getArtist() {
        return artist;
    }

    public void setArtist(String artist) {
        this.artist = artist;
    }

    public String getAlbum() {
        return album;
    }

    public void setAlbum(String album) {
        this.album = album;
    }

    @Override
    public String toString() {
        return artist + " - " + album + "\n";
    }
}

Answer 1

问题出在文件上。最初，我尝试使用 music.ser 并创建了一个 GUI，并尝试从 GUI 添加两位艺术家以及您上面提供的三位艺术家。

我尝试对它们进行序列化和反序列化，结果很顺利。后来我尝试从 GUI 添加另一个元素，在尝试序列化和反序列化时，我发现它没有正确序列化。

后来我将文件名更改为 test.ser，当我尝试从 GUI 添加三位艺术家和从运行时添加三位艺术家时，一切正常，当我尝试从 GUI 添加第四个艺术家时，它再次失败。

您需要做的就是删除该文件(如果存在)并在序列化和反序列化时创建一个新文件。

附上示例代码。

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;


    public class TestGUI {
        public static void main(String args[]) {

            final ArrayList<Music> musicList = new ArrayList<Music>();

            //Creating the Frame
            JFrame frame = new JFrame("Chat Frame");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setSize(400, 400);

            //Creating the MenuBar and adding components
            JMenuBar mb = new JMenuBar();
            JMenu m1 = new JMenu("FILE");
            JMenu m2 = new JMenu("Help");
            mb.add(m1);
            mb.add(m2);
            JMenuItem m11 = new JMenuItem("Open");
            JMenuItem m22 = new JMenuItem("Save as");
            m1.add(m11);
            m1.add(m22);

            //Creating the panel at bottom and adding components
            JPanel panel = new JPanel(); // the panel is not visible in output
            JLabel label = new JLabel("Enter Artist");
            final JTextField tf = new JTextField(10); // accepts upto 10 characters
            JLabel album = new JLabel("Enter Album");
            final JTextField tf1 = new JTextField(10);
            JButton send = new JButton("Send");
            JButton reset = new JButton("Serialize");
            panel.add(label); // Components Added using Flow Layout
            panel.add(label); // Components Added using Flow Layout
            panel.add(tf);
            panel.add(album); // Components Added using Flow Layout
            panel.add(tf1);
            panel.add(send);
            panel.add(reset);

            send.addActionListener(new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent arg0) {

                    Music m = new Music(tf.getText(), tf1.getText());
                    musicList.add(m);
                    tf1.setText("");
                    tf.setText("");

                }
            });

            reset.addActionListener(new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent arg0) {
                    try { 

                    TestSerialization.serializeAndDeserialize(musicList);
                    } catch (Exception ex) { 

                    }
                }
            });

            //Adding Components to the frame.
            frame.getContentPane().add(BorderLayout.CENTER, panel);
            frame.getContentPane().add(BorderLayout.NORTH, mb);

            frame.setVisible(true);
        }
    }

示例音乐(与您的相同)

import java.io.Serializable;

import javax.swing.JTextArea;


public class Music implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private String artist;
    private String album;
    JTextArea textArea;

    public Music(String artist, String album) {
        super();
        this.artist = artist;
        this.album = album;
    }

    public String getArtist() {
        return artist;
    }

    public void setArtist(String artist) {
        this.artist = artist;
    }

    public String getAlbum() {
        return album;
    }

    public void setAlbum(String album) {
        this.album = album;
    }

    @Override
    public String toString() {
        return artist + " - " + album + "\n";
    }
}

序列化类示例

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;


public class TestSerialization {


    public static ArrayList<Music> serializeAndDeserialize(ArrayList<Music> musicList) throws Exception { 

        musicList.add(new Music("Metallica", "Master of Puppets"));
        musicList.add(new Music("Pantera", "Far Beyond Driven"));
        musicList.add(new Music("Kognitif", "Soul Food"));

        // serialization method
        try {
            File f = new File("test.ser");
            if (f.exists()) { 
                f.delete();
            }
            FileOutputStream fos = new FileOutputStream("test.ser", true);
            ObjectOutputStream oos = new ObjectOutputStream(fos);
            oos.writeObject(musicList);
            oos.close();
            fos.close();
            for (Music m : musicList) {
                System.out.println("AddMusic: " + m);
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }

        // deserialization method
        ArrayList<Music> musicList2 = new ArrayList<Music>();
        try {
            FileInputStream fis = new FileInputStream("test.ser");
            ObjectInputStream ois = new ObjectInputStream(fis);
            musicList2 = (ArrayList<Music>) ois.readObject();
            ois.close();
            fis.close();                
            for (Music m : musicList2) {
                System.out.println("Reading Music: \n" + m.getArtist() + " - " + m.getAlbum());
            }               

            }
         catch (Exception ex) {
            ex.printStackTrace();
        }
        return musicList2;
    }

}