java - 无法访问 SwingWorker 的变量

Question

我正在尝试让这个 SwingWorker 正常运行。然而，需要访问的变量似乎不是全局的。我该怎么办？我尝试添加静态，但它会在以后从非静态访问静态时产生更多错误和复杂性。在 SwingWorker 中不起作用的变量是 LOCAL_FILE 和 URL_LOCATION 变量。

package professorphysinstall;

//Imports
import com.sun.jmx.snmp.tasks.Task;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Insets;
import java.awt.Label;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import java.util.Arrays;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.JTextPane;
import javax.swing.SwingWorker;
import javax.tools.FileObject;
import net.sf.sevenzipjbinding.ExtractOperationResult;
import net.sf.sevenzipjbinding.ISequentialOutStream;
import net.sf.sevenzipjbinding.ISevenZipInArchive;
import net.sf.sevenzipjbinding.SevenZip;
import net.sf.sevenzipjbinding.SevenZipException;
import net.sf.sevenzipjbinding.impl.RandomAccessFileInStream;
import net.sf.sevenzipjbinding.simple.ISimpleInArchive;
import net.sf.sevenzipjbinding.simple.ISimpleInArchiveItem;
import org.apache.commons.vfs2.AllFileSelector;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.FileSystemManager;
import org.apache.commons.vfs2.VFS;

public class ProfessorPhysInstall {

/**
 * @param args the command line arguments
 */

static class Global {
   public String location;
}

public static void main(String[] args) {
    // TODO code application logic here
    //Variables
    final JFrame mainframe = new JFrame();
    mainframe.setSize(500, 435);
    final JPanel cards = new JPanel(new CardLayout());
    final CardLayout cl = (CardLayout)(cards.getLayout());
    mainframe.setTitle("Future Retro Gaming Launcher");
    //Screen1
    JPanel screen1 = new JPanel();
    JTextPane TextPaneScreen1 = new JTextPane();
    TextPaneScreen1.setEditable(false);
    TextPaneScreen1.setBackground(new java.awt.Color(240, 240, 240));
    TextPaneScreen1.setText("Welcome to the install wizard  for Professor Phys!\n\nPlease agree to the following terms and click the next button to continue.");
    TextPaneScreen1.setSize(358, 48);
    TextPaneScreen1.setLocation(0, 0);
    TextPaneScreen1.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.black),BorderFactory.createEmptyBorder(5, 5, 5, 5)));
    TextPaneScreen1.setMargin(new Insets(4,4,4,4));
    screen1.add(TextPaneScreen1);
    JTextArea TextAreaScreen1 = new JTextArea();
    JScrollPane sbrText = new JScrollPane(TextAreaScreen1);
    TextAreaScreen1.setRows(15);
    TextAreaScreen1.setColumns(40);
    TextAreaScreen1.setEditable(false);
    TextAreaScreen1.setText("stuff");
    TextAreaScreen1.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.black),BorderFactory.createEmptyBorder(5, 5, 5, 5)));
    TextAreaScreen1.setMargin(new Insets(4,4,4,4));
    screen1.add(sbrText);
    final JCheckBox Acceptance = new JCheckBox();
    Acceptance.setText("I Accept The EULA Agreenment.");
    screen1.add(Acceptance);
    final JButton NextScreen1 = new JButton();
    NextScreen1.setText("Next");
    NextScreen1.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            if(Acceptance.isSelected())
                cl.next(cards);
        }
    });      
    screen1.add(NextScreen1);        
    JButton CancelScreen1 = new JButton();
    CancelScreen1.setText("Cancel");
    CancelScreen1.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            System.exit(0);
        }
    });      
    screen1.add(CancelScreen1);
    cards.add(screen1);

    //Screen2
    final JPanel screen2 = new JPanel();
    JPanel screen3 = new JPanel();
    JTextPane TextPaneScreen2 = new JTextPane();
    TextPaneScreen2.setEditable(false);
    TextPaneScreen2.setBackground(new java.awt.Color(240, 240, 240));
    TextPaneScreen2.setText("Please select the Future Retro Gaming Launcher. Professor Phys will be installed there.");
    TextPaneScreen2.setSize(358, 48);
    TextPaneScreen2.setLocation(0, 0);
    TextPaneScreen2.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.black),BorderFactory.createEmptyBorder(5, 5, 5, 5)));
    TextPaneScreen2.setMargin(new Insets(4,4,4,4));
    screen2.add(TextPaneScreen2);
    JLabel screen2instructions = new JLabel();
    screen2instructions.setText("Launcher Location: ");
    screen2.add(screen2instructions);
    final JTextField folderlocation = new JTextField(25);
    screen2.add(folderlocation);
    final JButton Browse = new JButton();
    final JLabel filelocation = new JLabel();
    final JLabel filename = new JLabel();
    Browse.setText("Browse");
    Browse.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            //Create a file chooser
            JFileChooser fc = new JFileChooser();
            fc.showOpenDialog(screen2);
            folderlocation.setText(fc.getSelectedFile().getAbsolutePath());
            filelocation.setText(fc.getCurrentDirectory().getAbsolutePath());
            filename.setText(fc.getSelectedFile().getName());
        }
    });   
    screen2.add(filelocation);
    screen2.add(filename);
    screen3.add(filelocation);
    filelocation.setVisible(false);
    filename.setVisible(false);
    screen2.add(Browse);
    final JButton BackScreen2 = new JButton();
    BackScreen2.setText("Back");
    BackScreen2.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            if(Acceptance.isSelected())
                cl.previous(cards);
        }
    });    
    screen2.add(BackScreen2);     
    final JButton NextScreen2 = new JButton();
    NextScreen2.setText("Next");
    NextScreen2.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            //Checking Code
            String correctname = "Future_Retro_Gaming_Launcher.jar";
    if (filename.getText().equals(correctname))
    {
        cl.next(cards);
    }
    else
    {
        JFrame popup = new JFrame();
        popup.setBounds(0, 0, 380, 100);
        Label error = new Label();
        error.setText("Sorry you must select your Future_Retro_Gaming_Launcher.jar");
        popup.add(error);
        popup.show();
    }
        }
    });      
    screen2.add(NextScreen2);        
    JButton CancelScreen2 = new JButton();
    CancelScreen2.setText("Cancel");
    CancelScreen2.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            System.exit(0);
        }
    });      
    screen2.add(CancelScreen2);
    cards.add(screen2);
    //Screen3
    JTextPane TextPaneScreen3 = new JTextPane();
    TextPaneScreen3.setEditable(false);
    TextPaneScreen3.setBackground(new java.awt.Color(240, 240, 240));
    TextPaneScreen3.setText("Professor Phys will be instaleld in the directory you have chosen. Please make sure\nyour launcher is in that folder or the game will not work.\nClick next to begin the install process.");
    TextPaneScreen3.setSize(358, 48);
    TextPaneScreen3.setLocation(0, 0);
    TextPaneScreen3.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.black),BorderFactory.createEmptyBorder(5, 5, 5, 5)));
    TextPaneScreen3.setMargin(new Insets(4,4,4,4));
    screen3.add(TextPaneScreen3);
    final JButton BackScreen3 = new JButton();
    BackScreen3.setText("Back");
    BackScreen3.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            if(Acceptance.isSelected())
                cl.previous(cards);
        }
    });    
    screen3.add(BackScreen2);     
    final JButton NextScreen3 = new JButton();
    NextScreen3.setText("Next");
    NextScreen3.addActionListener(new ActionListener() {
        @Override
        @SuppressWarnings({"null", "ConstantConditions"})
        public void actionPerformed(ActionEvent ae) {
            //ProgressBar/Install
            System.out.println("FILELOCATION:\n----------");
            System.out.println(filelocation.getText());
            String URL_LOCATION = "https://dl.dropboxusercontent.com/u/10429987/Future%20Retro%20Gaming/ProfessorPhys.iso";
            String LOCAL_FILE = (filelocation.getText() + "\\ProfessorPhys\\");
            System.out.println("LOCALFILE:\n-------");
            System.out.println(LOCAL_FILE);


            RandomAccessFile randomAccessFile = null;
    ISevenZipInArchive inArchive = null;
    try {
        randomAccessFile = new RandomAccessFile(LOCAL_FILE+"professorphys.iso", "r");
        inArchive = SevenZip.openInArchive(null, // autodetect archive type
                new RandomAccessFileInStream(randomAccessFile));

        // Getting simple interface of the archive inArchive
        ISimpleInArchive simpleInArchive = inArchive.getSimpleInterface();

        System.out.println("   Hash   |    Size    | Filename");
        System.out.println("----------+------------+---------");

        for (ISimpleInArchiveItem item : simpleInArchive.getArchiveItems()) {
            final int[] hash = new int[] { 0 };
            if (!item.isFolder()) {
                ExtractOperationResult result;

                final long[] sizeArray = new long[1];
                result = item.extractSlow(new ISequentialOutStream() {
                    public int write(byte[] data) throws SevenZipException {
                        hash[0] ^= Arrays.hashCode(data); // Consume data
                        sizeArray[0] += data.length;
                        return data.length; // Return amount of consumed data
                    }
                });
                if (result == ExtractOperationResult.OK) {
                    System.out.println(String.format("%9X | %10s | %s", // 
                            hash[0], sizeArray[0], item.getPath()));
                } else {
                    System.err.println("Error extracting item: " + result);
                }
            }
        }
    } catch (Exception e) {
        System.err.println("Error occurs: " + e);
        System.exit(1);
    } finally {
        if (inArchive != null) {
            try {
                inArchive.close();
            } catch (SevenZipException e) {
                System.err.println("Error closing archive: " + e);
            }
        }
        if (randomAccessFile != null) {
            try {
                randomAccessFile.close();
            } catch (IOException e) {
                System.err.println("Error closing file: " + e);
            }
        }
    }
}

    });        
    screen3.add(NextScreen3);        
    JButton CancelScreen3 = new JButton();
    CancelScreen3.setText("Cancel");
    CancelScreen3.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            System.exit(0);
        }
    });      
    screen3.add(CancelScreen3);

    System.out.println("Done");
    JProgressBar progress = new JProgressBar();
    progress.setIndeterminate(true);
    screen3.add(progress);
    cards.add(screen3);
    mainframe.add(cards);
    mainframe.setVisible(true);
}
}

class DownloadWorker extends SwingWorker<Integer, Integer>
{
protected Integer doInBackground() throws Exception
{
    try {
            URL website = new URL(URL_LOCATION);
            ReadableByteChannel rbc = Channels.newChannel(website.openStream());
            FileOutputStream fos = new FileOutputStream(LOCAL_FILE+"\\ProfessorPhys.iso\\");
            fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
            System.out.println("--------\nDone Downloading\n---------");
            } catch (Exception e) {
                System.err.println(e);
            }
    return 42;
}

protected void done()
{
    try
    {
        System.out.println("done");
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
}
}

Answer 1

你的程序主要是一个巨大的静态主方法。在首先创建干净的 OOP 代码之前，尝试进行高级编程(例如使用 SwingWorker)有点本末倒置。换句话说——重新开始并把事情做好。那么类之间的联系就会更加自然，并且更加更容易让事情正常工作。 main 方法应该只关心启动 Swing 事件线程、在该线程中创建 GUI 对象并显示它。其他所有内容都应该位于创建对象的类中。

此外，在更实际的层面上，您还没有告诉我们哪些变量给您带来了麻烦或者您可能会看到哪些错误。另外，您要在哪里尝试创建和执行 SwingWorker？

<小时/>

编辑

一个可能会有所帮助的提示:为您的 SwingWorker 类提供一个构造函数，并通过构造函数参数将重要参数传递到您的 SwingWorker 对象中。然后使用这些参数来初始化将在 SwingWorker 的 doInBackground 方法中使用的类字段。

例如，

class DownloadWorker extends SwingWorker<Integer, Integer>
{
private String urlLocation;
private String localFile;

public DownLoadWorker(String urlLocation, String localFile) {
  this.urlLocation = urlLocation;
  this.localFile = localFile;
}


protected Integer doInBackground() throws Exception
{
    try {
            URL website = new URL(urlLocation);
            ReadableByteChannel rbc = Channels.newChannel(website.openStream());
            FileOutputStream fos = new FileOutputStream(localFile +"\\ProfessorPhys.iso\\");
            fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
            System.out.println("--------\nDone Downloading\n---------");
            } catch (Exception e) {
                System.err.println(e);
            }
    return 42;
}

protected void done()
{
    try
    {
        System.out.println("done");
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
}
}