帶有SwingWorker的Java-按下按鈕后GUI凍結（ProgressBar也不起作用）

Question

我程序的主要思想是從文件中解析XML數據，然后使用JDBC驅動程序將其插入MySQL數據庫。 文件包含2000個元素，一切正常運行-解析文件並將數據加載到數據庫。 問題是，當我按下按鈕啟動所有GUI時，JProgressBarr無法正常工作。 我不知道為什么。 我使用SwingWorker進行線程工作。 這是我的代碼：

package javamysqlinsert;

import java.awt.Container;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.HashMap;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.border.EmptyBorder;
import javax.swing.filechooser.FileNameExtensionFilter;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class JavaMySqlInsert extends JFrame implements ActionListener {

    private final String DEFAULT_DRIVER = "com.mysql.jdbc.Driver";
    private final String DB_URL = "jdbc:mysql://anton869.linuxpl.eu:3306/" 
            + "anton869_cars"; 
    private final String DB_USER = "user";
    private final String DB_PASSWORD = "user";

    private JTextField xmlPathField;
    private JButton chooseFileButton, insertDataButton;
    private JProgressBar insertProgressBar;
    private String filePath;

    class LoadXmlToDatabase extends SwingWorker<Void, Void> {

        @Override
        public Void doInBackground() {
            JavaMySqlInsert.this.insertProgressBar.setIndeterminate(true);
            loadAndParseXml();
            return null;
        }

        @Override
        public void done() {
            JavaMySqlInsert.this.insertProgressBar.setIndeterminate(false);
            JOptionPane.showMessageDialog(JavaMySqlInsert.this, 
                    "Finished loading data to MySQL database", 
                    "Loading success", JOptionPane.INFORMATION_MESSAGE);
        }

        private void loadAndParseXml() {
            try {
                DocumentBuilderFactory dbf = DocumentBuilderFactory
                        .newInstance();
                DocumentBuilder db = dbf.newDocumentBuilder();
                Document doc = db.parse(new File(JavaMySqlInsert.this
                        .filePath));
                doc.getDocumentElement().normalize();
                System.out.println("Successfully loaded XML file");
                fillItemList(doc); 
            } catch (IOException | ParserConfigurationException 
                    | SAXException e) {
            }
        }

        private void fillItemList(final Document doc) {
            try {            
                System.out.println("Connecting to MySQL database...");
                Class.forName(DEFAULT_DRIVER);
                Connection conn = DriverManager.getConnection(DB_URL, DB_USER, 
                        DB_PASSWORD);
                System.out.println("Connected to MySQL database");

                System.out.println("Starting parsing XML document and loading "
                        + "it to MySQL database...");
                NodeList nodesList = doc.getElementsByTagName("T");
                final int nodeListLength = nodesList.getLength();
                for (int i = 0; i < nodeListLength; i++) {
                    Node node = nodesList.item(i);
                    Element element = (Element) node;
                    HashMap<String, String> carMap = new HashMap<>();
                    if (node.getNodeType() == Node.ELEMENT_NODE) {
                        // <P_NAME>
                        carMap.put("p_name", element
                                .getElementsByTagName("P_NAME").item(0)
                                .getTextContent());
                        // <P_MFGR>
                        carMap.put("p_mfgr", element
                                .getElementsByTagName("P_MFGR").item(0)
                                .getTextContent());
                        // <P_BRAND>
                        carMap.put("p_brand", element
                                .getElementsByTagName("P_BRAND").item(0)
                                .getTextContent());
                        // <P_TYPE>
                        carMap.put("p_type", element
                                .getElementsByTagName("P_TYPE").item(0)
                                .getTextContent());
                        // <P_SIZE>
                        carMap.put("p_size", element
                                .getElementsByTagName("P_SIZE").item(0)
                                .getTextContent());
                        // <P_CONTAINER>
                        carMap.put("p_container", element
                                .getElementsByTagName("P_CONTAINER").item(0)
                                .getTextContent());
                        // <P_RETAILPRICE>
                        carMap.put("p_retailprice", element
                                .getElementsByTagName("P_RETAILPRICE").item(0)
                                .getTextContent());
                        // <P_COMMENT>
                        carMap.put("p_comment", element
                                .getElementsByTagName("P_COMMENT").item(0)
                                .getTextContent());
                    }
                    insertCarInfoRow(conn, carMap);
                }
                System.out.println("Data have been successfully parsed and "
                        + "loaded to MySQL database. Inserted: " 
                        + nodeListLength + " rows");
            } catch (SQLException | ClassNotFoundException e) {
            }
        }

        private void insertCarInfoRow(final Connection conn, 
                final HashMap<String, String> carMap) {
            final String insertQuery = "INSERT INTO part (p_name, p_mfgr, "
                    + "p_brand, p_type, p_size, p_container, p_retailprice, "
                    + "p_comment) VALUES (?, ?, ?, ?, ?, ?, ?, ?)";

            try (PreparedStatement ps = conn.prepareStatement(insertQuery)) {
                ps.setString(1, carMap.get("p_name"));
                ps.setString(2, carMap.get("p_mfgr"));
                ps.setString(3, carMap.get("p_brand"));
                ps.setString(4, carMap.get("p_type"));
                ps.setInt(5, Integer.parseInt(carMap.get("p_size")));
                ps.setString(6, carMap.get("p_container"));
                ps.setFloat(7, Float.parseFloat(carMap.get("p_retailprice")));
                ps.setString(8, carMap.get("p_comment"));
                ps.executeUpdate();
                ps.close();
            } catch (SQLException e) {
            }
        }

    }

    public JavaMySqlInsert() {
        setBasicProperties();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource().equals(this.insertDataButton)) {
            if (testInternetConnection("google.com")) {
                new LoadXmlToDatabase().run();
            } else JOptionPane.showMessageDialog(this, 
                    "You have no Internet connection", "Network error", 
                    JOptionPane.ERROR_MESSAGE); 
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                JavaMySqlInsert jmsqli = new JavaMySqlInsert();
                jmsqli.setLocationRelativeTo(null);
                jmsqli.setVisible(true);  
            }

        });
    }

}

Answer 1

更改此：

new LoadXmlToDatabase().run();

..對此。

new LoadXmlToDatabase().execute();

Answer 2

GUI主要由於線程問題而凍結在Java中，在這種情況下，我猜它是因為單擊或按下按鈕時出現的。所以請嘗試為按鈕提供單獨的線程。嘗試此解決方案。

public void actionPerformed(ActionEvent e) {

//declare the variables you have (if any)

Thread t = new Thread() {

               @Override

             public void run() {  
                 //write you code here

                }

            };

        t.start();

}