Question

我正在尝试使用JFileChooser获取库存控制软件的数据库文件目录。

问题是JFileChooser只在文件浏览器显示两次并且文件被选中两次后才获取文件的目录。

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

您已使用procedure TForm1.FormCreate(Sender: TObject); var _Interf: IInterface; _Configuration: TDictionary<string, TValue>; _ObjectType: TObjectTypes; begin _Configuration := nil; _Configuration := TDictionary<string, TValue>.Create; try _Configuration.Add('FileLogFileName', '20160320.Log'); _Configuration.Add('SMTPEmailHost', 'mail.server.lt'); _Configuration.Add('POP3Server', 'some_server'); for _ObjectType := Low(TObjectTypes) to High(TObjectTypes) do begin _Interf := TTheFactory.Make(_ObjectType, _Configuration); if Assigned(_Interf) then begin OutputDebugString(PWideChar((_Interf as TObject).ClassName)); if Supports(_Interf, IEmail) then (_Interf as IEmail).Send('X'); if Supports(_Interf, ILogger) then (_Interf as ILogger).GetLastErrorMsg; end; end; finally FreeAndNil(_Configuration); end; end;类

扩展DisplayDatabase

GetDatabase

所以当你创建一个超级类[DisplayDatabase extends GetDatabase{ ... }的{{1}}类构造函数的新实例时，会调用get和connect方法再次调用。

所以你得到另一个GetDatabase弹出窗口。

GetDatabase

所以如何修复

如果您不想继承jfilechooser课程中的任何内容，则可以删除扩展部分。

但是如果你想继承GetDatabase database = new GetDatabase();类，那么

而不是从构造函数连接db，您可以从方法中完成。

GetDatabase

所以你打电话给这个方法。

GetDatabase

Answer 2

可能是该函数被多次触发，您调用文件选择器的代码似乎工作正常。

在选择项目之前，JFileChooser会两次调用文件资源管理器

2 个答案: