从文件系统加载对象后更新 GUI

Question

我是 Java 新手，我正在开发我的第一个 Java 项目。到目前为止，它由一个带有动态生成表单的 GUI（改编自 this question）、一个 Save 按钮和一个 Load 按钮组成。使用 Save 按钮，将整个表单保存为一个对象，使用 Load 按钮，可以加载现有的已保存表单。保存和加载自己似乎可以工作，但是在我（间接，即通过另一个函数）在 加载按钮：

public class LoadListener extends SingleFileChooser implements ActionListener {

    private static final long serialVersionUID = -4418195536438874952L; 
    private EntryList listFromFile;
    private ScrollBar panel;

    @SuppressWarnings("hiding")
    public LoadListener(String choosertitle, ScrollBar panel) {
        super(choosertitle);
        this.panel = panel;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        super.actionPerformed(e);       
        try {
            InputStream is = new FileInputStream(this.getFilePath());
            ObjectInputStream ois = new ObjectInputStream(is);
            listFromFile = (EntryList) ois.readObject();
            ois.close();
            panel.setEntryList(listFromFile);
        } catch (FileNotFoundException e1) {
            System.out.println("File not found: " + this.getFilePath());
            e1.printStackTrace();
        } catch (IOException e1) {
            System.out.println("IO exception: " + this.getFilePath());
            e1.printStackTrace();
        } catch (ClassNotFoundException e1) {
            System.out.println("Class for input object not found: " + this.getFilePath());
            e1.printStackTrace();
        }
    }

    public EntryList getLoadedGatingList() {
        return listFromFile;
    }
}

这里，panel 是JPanel 的子类：

public class ScrollBar extends JPanel {

    private static final long serialVersionUID = -3460555902426579496L;
    private JScrollPane scrollPane;
    private JButton saveList, loadList;
    private EntryList entryList;

    @SuppressWarnings("hiding")
    public ScrollBar(EntryList entryList, MainFrame frame) {
        scrollPane = new JScrollPane(entryList,
                ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
                ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
        scrollPane.setPreferredSize(new Dimension(300,400));        
        this.entryList = entryList;
        saveList = new JButton("Save List");
        saveList.addActionListener(new SaveListener("Save List", this));
        loadList = new JButton("Load List");
        loadList.addActionListener(new LoadListener("Load List", this));
        add(scrollPane);
        add(saveList);
        add(loadList);
    }

    public EntryList getEntryList() {
        return entryList;
    }

    public void setEntryList(EntryList list) {
        entryList = list;
        this.saveList.setBackground(Color.PINK);
        this.saveList.setText(entryList.getFirstText());
        this.loadList.setBackground(Color.GREEN);
        revalidate();
        repaint();
    }
}

下面列出了运行示例所需的其余类：

public class Entry extends JPanel implements Serializable{

    private static final long serialVersionUID = 8748191176188997955L;
    private JTextField textField;
    private JButton plus;
    private JButton minus;
    private EntryList parent;

    public Entry(String textFieldText, EntryList list) {
        this.parent = list;
        this.plus = new JButton(new AddEntryAction());
        this.minus = new JButton(new RemoveEntryAction());
        this.textField = new JTextField(10);
        this.textField.setText(textFieldText);
        add(this.plus);
        add(this.minus);
        add(this.textField);
    }

    public String getText() {
        return this.textField.getText();
    }

    public class AddEntryAction extends AbstractAction {

        private static final long serialVersionUID = -1936452299010320790L;

        public AddEntryAction() {
            super("+");
        }

        public void actionPerformed(ActionEvent e) {
            parent.cloneEntry(Entry.this);
        }

    }

    public class RemoveEntryAction extends AbstractAction {

        private static final long serialVersionUID = 4843871176230776949L;

        public RemoveEntryAction() {
            super("-");
        }

        public void actionPerformed(ActionEvent e) {
            parent.removeItem(Entry.this);
        }
    }

    public void enableAdd(boolean enabled) {
        this.plus.setEnabled(enabled);
    }
    public void enableMinus(boolean enabled) {
        this.minus.setEnabled(enabled);
    }
}


public class EntryList extends JPanel implements Serializable{

    private static final long serialVersionUID = 1426379083556312697L;
    private List<Entry> entries;

    public EntryList() {
        this.entries = new ArrayList<Entry>();
        Entry initial = new Entry("debugtext", this);
        addItem(initial);
    }

    public int getLength() {
        return this.entries.size();
    }
    public String getFirstText() {
        return this.entries.get(0).getText();
    }

    public void cloneEntry(Entry entry) {
        Entry theClone = new Entry("", this);
        addItem(theClone);
    }

    private void addItem(Entry entry) {
        entries.add(entry);
        add(entry);
        refresh();
    }

    public void removeItem(Entry entry) {
        entries.remove(entry);
        remove(entry);
        refresh();
    }

    private void refresh() {
        revalidate();

        if (entries.size() == 1) {
            entries.get(0).enableMinus(false);
        }
        else {
            for (Entry e : entries) {
                e.enableMinus(true);
            }
        }
    }
}

public class SaveListener extends DirectoryChooser implements ActionListener {

    private static final long serialVersionUID = -8842006866700189526L;
    private EntryList list;
    private String filename;

    public SaveListener(String choosertitle, ScrollBar bar) {
        super(choosertitle, false);
        this.list = bar.getEntryList();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        super.actionPerformed(e);
        try {
            filename = this.getResultsDirectory();
            OutputStream os = new FileOutputStream(filename);
            ObjectOutputStream oos = new ObjectOutputStream(os);
            oos.writeObject(list);
            oos.close();
            System.out.println("Length of list at saving = " + this.list.getLength());
            System.out.println("Length of list at saving = " + this.list.getFirstText());

        } catch (FileNotFoundException e1) {
            System.out.println("File not found: " + filename);
            e1.printStackTrace();
        } catch (IOException e1) {
            System.out.println("IO Exception: " + e1);
            e1.printStackTrace();
        }
    }
}

public class DirectoryChooser extends JPanel implements ActionListener {

    private static final long serialVersionUID = -8143869075088499054L;
    private JButton setwd;
    private String workingdir;

    private JFileChooser chooser;
    private String choosertitle;
    private boolean directoryOnly = true;

    @SuppressWarnings("hiding")
    public DirectoryChooser(String choosertitle) {
        this.choosertitle = choosertitle;
        setwd = new JButton(choosertitle);
        setwd.addActionListener(this);
        add(setwd);
        workingdir = new File(System.getProperty("user.dir")).toString();
    }

    @SuppressWarnings("hiding")
    public DirectoryChooser(String choosertitle, boolean directoryOnly) {
        this(choosertitle);
        this.directoryOnly = directoryOnly;
    }

    public void actionPerformed(ActionEvent e) {    

        chooser = new JFileChooser(); 
        chooser.setCurrentDirectory(new java.io.File("."));
        chooser.setDialogTitle(choosertitle);
        if (directoryOnly) {
            chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
        }
        chooser.setAcceptAllFileFilterUsed(false);

        if (chooser.showOpenDialog(this) == JFileChooser.APPROVE_OPTION) { 
            workingdir = chooser.getSelectedFile().toString();
        } else {
            workingdir = chooser.getCurrentDirectory().toString();
        }
    }

    public String getResultsDirectory() {
        return workingdir;
    }

    public Dimension getPreferredSize(){
        return new Dimension(200, 200);
    }
}

public class SingleFileChooser extends JPanel implements ActionListener {

    private static final long serialVersionUID = -9068219101747975546L;
    private JButton loadFiles;
    private JFileChooser chooser;
    private String choosertitle;
    private File file;
    private String filePath;
    private FileNameExtensionFilter filter; 

    @SuppressWarnings("hiding")
    public SingleFileChooser(String choosertitle) {
        this.choosertitle = choosertitle;
        loadFiles = new JButton(choosertitle);
        loadFiles.addActionListener(this);
        add(loadFiles);
    }

    @SuppressWarnings("hiding")
    public SingleFileChooser(String choosertitle, FileNameExtensionFilter filter) {
        this(choosertitle);
        this.filter = filter;
    }

    public void actionPerformed(ActionEvent e) {    

        chooser = new JFileChooser(); 
        chooser.setMultiSelectionEnabled(false);
        if (filter != null) {
            chooser.setFileFilter(filter);
        }
        chooser.setDialogTitle(choosertitle);
        chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);


        int returnVal = chooser.showOpenDialog(null);
        if(returnVal == JFileChooser.APPROVE_OPTION) {
            file = chooser.getSelectedFile();
            filePath = file.getAbsolutePath();
        }
    }

    public File getFile() {
        return file;
    }

    public String getFilePath(){
        return filePath;
    }

    public Dimension getPreferredSize(){
        return new Dimension(200, 200);
    }
}

public class MainFrame extends JFrame {

    private static final long serialVersionUID = 512941639567306317L;
    EntryList panel = new EntryList();
    ScrollBar scrollPanel = new ScrollBar(panel, this);

    public MainFrame() throws HeadlessException {   
        this.getContentPane().add(scrollPanel);
        this.setLayout(new BoxLayout(this.getContentPane(), BoxLayout.Y_AXIS));
    }
}

public class GUImain {

    public static void main(String[] args) {
        MainFrame frame = new MainFrame();
        frame.pack();
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null); // center the window
    }
}

当我执行此代码时，修改文本字段中的文本，保存表单并再次加载，保存的文本没有加载到文本字段中，加载按钮消失。另一方面，Save 按钮被重新绘制：它变成粉红色并获得正确加载的文本字段内容。

所以我的问题是：如何正确加载保存的表单并防止按钮消失？

Answer 1

序列化 AWT 组件不是一个好主意，原因之一是与未来版本的兼容性。另一个是并非所有的摆动对象都实现可序列化。例如GridLayout 是不可序列化的。
存储重构和EntryList对象所需的所有信息，并在需要重构时使用它应该要简单得多。
重建Entry 只需要String，因此我建议将所有这些字符串存储在一个文件中，而不是尝试将EntryList 对象保存到文件中。
在检索到这些字符串后，每个字符串都代表一个Entry，您可以轻松地重构一个EntryList。

添加一个将Entry添加到EntryList的方法：

public void addItem(String text) {
    Entry entry = new Entry(text, this);
    entries.add(entry);
    add(entry);
}

当您想要重建 EntryList 时：

    //get all stored Entry strings from file into a List (for example) 
    List<String>entriesText = getEntriesStringsFromFile(); 

    EntryList eList = new EntryList(); //make a new EntryList 
    for (String text : entriesText){ //add all content to EntryList
        eList.addItem(text);
    }

现在你有一个完全重建的EntryList。
考虑添加一个接受List<String>entriesText 到EntryList 的构造函数。

---

旁注：我认为cloneEntry应该是：

public void cloneEntry(Entry entry) {
    Entry theClone = new Entry(entry.getText(), this);
    addItem(theClone);
}