如何将DefaultTableModel对象的数据获取到DefaultTableModel的子类中 [英] How to get a DefaultTableModel object's data into a subclass of DefaultTableModel

问题描述

我有一个jTable显示一个简单的两列sql表的数据，并允许用户维护该列表.这是我的第一个Java程序.使该功能生效，以便用户可以编辑数据列表，然后按保存进行更新. 我从以下代码行将sql数据获取到jTable的DefaultTableModel中:

I have a jTable displaying a simple two column sql table's data and allowing a user to maintain the list. This is my first java program. Have that working such that user can edit the list of data and press save to update. I get the sql data to the jTable's DefaultTableModel from this line of code:

paCutAboveTable.SetTableModel((DefaultTableModel) DbUtils.resultSetToTableModel(rs));

我猜这里的人熟悉DBUtils和resultSet. 我想向每行添加一个CheckBox.在这里和其他地方，我一直在寻找DefaultTableModel的子类，以便因此重写方法:

I'm guessing DBUtils and resultSets are familiar to people here. I want to add a CheckBox to each row. Looking here and elsewhere I kept seeing to subclass DefaultTableModel in order to override a method thus:

/*

  * JTable uses this method to determine the default renderer/
  * editor for each cell.  If we didn't implement this method,
  * then the last column would contain text ("true"/"false"),
  * rather than a check box.
  */

 public Class getColumnClass(int c) {

     return getValueAt(0, c).getClass();
   }

但是我不知道如何将DefaultTableModel的输出从resultSetToTableModel方法传递到我的子类-如果将SetTableModel方法更改为接受子类作为其参数，则显示的语句不会编译. 我想念一个简单的方法吗?

However I can't figure how to get the output of DefaultTableModel from resultSetToTableModel method to my subclass - the statement shown doesn't compile if the SetTableModel method is changed to accept the subclass as its parameter. Is there an easy way I'm missing?

推荐答案

以下示例显示了如何从ResultSet中读取数据并在自己的自定义DefaultTableModel中实现getColumnClass(...)方法:

Here is an example that shows how to read the data from the ResultSet and implement the getColumnClass(...) method in your own custom DefaultTableModel:

import java.awt.*;
import java.sql.*;
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;

public class TableFromDatabase extends JFrame
{
    public TableFromDatabase()
    {
        Vector<Object> columnNames = new Vector<Object>();
        Vector<Object> data = new Vector<Object>();

        try
        {
            //  Connect to an Access Database

            String driver = "sun.jdbc.odbc.JdbcOdbcDriver";
//            String url = "jdbc:odbc:???";  // if using ODBC Data Source name
            String url =
                "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=c:/directory/???.mdb";
            String userid = "";
            String password = "";

            Class.forName( driver );
            Connection connection = DriverManager.getConnection( url, userid, password );

            //  Read data from a table

            String sql = "Select * from ???";
            Statement stmt = connection.createStatement();
            ResultSet rs = stmt.executeQuery( sql );
            ResultSetMetaData md = rs.getMetaData();
            int columns = md.getColumnCount();

            //  Get column names

            for (int i = 1; i <= columns; i++)
            {
                columnNames.addElement( md.getColumnLabel(i) );
            }

            //  Get row data

            while (rs.next())
            {
                Vector<Object> row = new Vector<Object>(columns);

                for (int i = 1; i <= columns; i++)
                {
                    row.addElement( rs.getObject(i) );
                }

                data.addElement( row );
            }

            rs.close();
            stmt.close();
            connection.close();
        }
        catch(Exception e)
        {
            System.out.println( e );
        }

        //  Create table with database data

        DefaultTableModel model = new DefaultTableModel(data, columnNames)
        {
            @Override
            public Class getColumnClass(int column)
            {
                for (int row = 0; row < getRowCount(); row++)
                {
                    Object o = getValueAt(row, column);

                    if (o != null)
                    {
                        return o.getClass();
                    }
                }

                return Object.class;
            }
        };

        JTable table = new JTable( model );
        JScrollPane scrollPane = new JScrollPane( table );
        add( scrollPane );

        JPanel buttonPanel = new JPanel();
        add( buttonPanel, BorderLayout.SOUTH );
    }

    public static void main(String[] args)
    {
        TableFromDatabase frame = new TableFromDatabase();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
        frame.pack();
        frame.setVisible(true);
    }
}

通过覆盖getColumnClass(...)方法，您现在将看到数字格式右对齐，并且如果您需要对数据进行排序，由于列将基于数字值而不是字符串值进行排序，因此它将可以正常工作.

By overriding the getColumnClass(...) method you will now see number formatted right aligned and if you ever need to sort the data it will work properly since the column will be sorted based on a numeric value not a String value.

我想向每行添加一个CheckBox.

I want to add a CheckBox to each row.

因此，您现在有两个选择:

So now you have two options:

1. 修改上面的代码，以使"columnNames"向量包含复选框列的另一个标头名称，并在您遍历ResultSet时向每个行"向量添加Boolean.FALSE.

照原样使用上面的TableModel(或使用DbUtils TableModel)，然后创建包装器TableModel，该包装器将在任何现有TableModel中添加一个复选框列.检出:如何在已填充的Jtable中添加复选框使用rs2xml 作为该方法的示例.

Use the above TableModel as is (or use the DbUtils TableModel) and then create a wrapper TableModel that will add a check box column to any existing TableModel. Check out: How to add checkbox in Jtable populated using rs2xml for an example of this approach.

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