java JFileChooser在选择项之前调用文件资源管理器两次

Question

我正在尝试使用JFileChooser为我的库存控制软件获取数据库文件的目录

问题是，JFileChooser仅在文件资源管理器显示两次并选择两次文件后才能获取文件的目录

代码如下：

package groupassignment;
import java.io.File;
import java.sql.Connection;
import java.sql.*;
import java.sql.SQLException;
import javax.swing.*;

/**
 *
 * @author ashraf141298
 */ 
public class GetDatabase {
    static Connection con;
    static Statement st;
    static ResultSet rs;

    public GetDatabase() {
        connect();
    }

    public String getFileDirectory() {
        JFileChooser filechooser = new JFileChooser();
        File db = null;
        String directory;

        if(filechooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
            db = filechooser.getSelectedFile();
            System.out.println("Opening file: " + db);
        } else {
            System.out.println("No file was chosen or an error occured");
            System.exit(0);
        };

        directory = db.toString();
        return directory;
    }

    public void connect() {
        try{
            String dbURL = "jdbc:ucanaccess://" + getFileDirectory();

            // Attempt to connect to the database
            con = DriverManager.getConnection(dbURL);

            // Extract data from the table using SQL sta
            st = con.createStatement();
            String query = "select * from ProductBarcodes";
            rs = st.executeQuery(query);
        } catch(SQLException e){
            JOptionPane.showMessageDialog(null, "Unable to connect to database", "Error", JOptionPane.ERROR_MESSAGE);
            System.exit(0);
        } 
    }

    public static void main(String[] args) {
        GetDatabase database = new GetDatabase();
        DisplayDatabase gui = new DisplayDatabase();
    }
}

DisplayDatabase的代码：

package groupassignment;
import static groupassignment.GetDatabase.rs;
import javax.swing.*;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.Vector;
import javax.swing.table.DefaultTableModel;

/**
 *
 * @author ashraf141298
 */
public class DisplayDatabase extends GetDatabase {
    public DisplayDatabase() {
        display();
    }

    public void display() {
        // It creates and displays the table
        JTable table = null;

        try {
            table = new JTable(buildTableModel(rs));
        } catch (SQLException ex) {
            System.out.println("Unable to create JTable");
        }

        // Closes the Connection
        JOptionPane.showMessageDialog(null, new JScrollPane(table), "Current Stocklist", JOptionPane.INFORMATION_MESSAGE);
    }

    public static DefaultTableModel buildTableModel(ResultSet rs) throws SQLException {
        ResultSetMetaData metaData = rs.getMetaData();

        // get the names of columns 
        Vector<String> columnNames = new Vector<String>();
        int columnCount = metaData.getColumnCount();
        for (int column = 1; column <= columnCount; column++) {
            columnNames.add(metaData.getColumnName(column));
        }

        // get the data of the table
        Vector<Vector<Object>> data = new Vector<Vector<Object>>();
        while (rs.next()) {
            Vector<Object> vector = new Vector<Object>();
            for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
                vector.add(rs.getObject(columnIndex));
            }
            data.add(vector);
        }

        // return the database in TableModel form
        return new DefaultTableModel(data, columnNames);

     }                

}

Answer 1

您已经用GetDatabase类扩展了DisplayDatabase

DisplayDatabase extends GetDatabase{
  ...
}

因此，当您创建超级类[GetDatabase]的GetDatabase类构造函数的新实例时，将再次调用connect方法

因此，您将获得另一个jfilechooser弹出窗口

 GetDatabase database = new GetDatabase();

那么如何修复呢

如果您不想从GetDatabase类继承任何内容，可以删除扩展部分

但是如果您想从GetDatabase类继承

您可以通过一个方法来完成，而不是从构造函数连接数据库

public GetDatabase() {
   // connect();// not here
}

public void ConnectDatabase(){
    connect();
}

所以你称之为这个方法

public static void main(String[] args) {
    GetDatabase database = new GetDatabase();
    database.ConnectDatabase();
    DisplayDatabase gui = new DisplayDatabase();
}

Answer 2

可能该函数被多次触发，调用文件选择器的代码似乎工作正常