Mega Code Archive
This program uses metadata to display arbitrary tables in a database
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/*
This program is a part of the companion code for Core Java 8th ed.
(http://horstmann.com/corejava)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import com.sun.rowset.*;
import java.sql.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import javax.sql.*;
import javax.sql.rowset.*;
/**
* This program uses metadata to display arbitrary tables in a database.
* @version 1.31 2007-06-28
* @author Cay Horstmann
*/
public class ViewDB
{
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
JFrame frame = new ViewDBFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}
/**
* The frame that holds the data panel and the navigation buttons.
*/
class ViewDBFrame extends JFrame
{
public ViewDBFrame()
{
setTitle("ViewDB");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
tableNames = new JComboBox();
tableNames.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
showTable((String) tableNames.getSelectedItem());
}
});
add(tableNames, BorderLayout.NORTH);
try
{
readDatabaseProperties();
Connection conn = getConnection();
try
{
DatabaseMetaData meta = conn.getMetaData();
ResultSet mrs = meta.getTables(null, null, null, new String[] { "TABLE" });
while (mrs.next())
tableNames.addItem(mrs.getString(3));
}
finally
{
conn.close();
}
}
catch (SQLException e)
{
JOptionPane.showMessageDialog(this, e);
}
catch (IOException e)
{
JOptionPane.showMessageDialog(this, e);
}
JPanel buttonPanel = new JPanel();
add(buttonPanel, BorderLayout.SOUTH);
previousButton = new JButton("Previous");
previousButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
showPreviousRow();
}
});
buttonPanel.add(previousButton);
nextButton = new JButton("Next");
nextButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
showNextRow();
}
});
buttonPanel.add(nextButton);
deleteButton = new JButton("Delete");
deleteButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
deleteRow();
}
});
buttonPanel.add(deleteButton);
saveButton = new JButton("Save");
saveButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
saveChanges();
}
});
buttonPanel.add(saveButton);
}
/**
* Prepares the text fields for showing a new table, and shows the first row.
* @param tableName the name of the table to display
*/
public void showTable(String tableName)
{
try
{
// open connection
Connection conn = getConnection();
try
{
// get result set
Statement stat = conn.createStatement();
ResultSet result = stat.executeQuery("SELECT * FROM " + tableName);
// copy into cached row set
crs = new CachedRowSetImpl();
crs.setTableName(tableName);
crs.populate(result);
}
finally
{
conn.close();
}
if (scrollPane != null) remove(scrollPane);
dataPanel = new DataPanel(crs);
scrollPane = new JScrollPane(dataPanel);
add(scrollPane, BorderLayout.CENTER);
validate();
showNextRow();
}
catch (SQLException e)
{
JOptionPane.showMessageDialog(this, e);
}
}
/**
* Moves to the previous table row.
*/
public void showPreviousRow()
{
try
{
if (crs == null || crs.isFirst()) return;
crs.previous();
dataPanel.showRow(crs);
}
catch (SQLException e)
{
for (Throwable t : e)
t.printStackTrace();
}
}
/**
* Moves to the next table row.
*/
public void showNextRow()
{
try
{
if (crs == null || crs.isLast()) return;
crs.next();
dataPanel.showRow(crs);
}
catch (SQLException e)
{
JOptionPane.showMessageDialog(this, e);
}
}
/**
* Deletes current table row.
*/
public void deleteRow()
{
try
{
Connection conn = getConnection();
try
{
crs.deleteRow();
crs.acceptChanges(conn);
if (!crs.isLast()) crs.next();
else if (!crs.isFirst()) crs.previous();
else crs = null;
dataPanel.showRow(crs);
}
finally
{
conn.close();
}
}
catch (SQLException e)
{
JOptionPane.showMessageDialog(this, e);
}
}
/**
* Saves all changes.
*/
public void saveChanges()
{
try
{
Connection conn = getConnection();
try
{
dataPanel.setRow(crs);
crs.acceptChanges(conn);
}
finally
{
conn.close();
}
}
catch (SQLException e)
{
JOptionPane.showMessageDialog(this, e);
}
}
private void readDatabaseProperties() throws IOException
{
props = new Properties();
FileInputStream in = new FileInputStream("database.properties");
props.load(in);
in.close();
String drivers = props.getProperty("jdbc.drivers");
if (drivers != null) System.setProperty("jdbc.drivers", drivers);
}
/**
* Gets a connection from the properties specified in the file database.properties
* @return the database connection
*/
private Connection getConnection() throws SQLException
{
String url = props.getProperty("jdbc.url");
String username = props.getProperty("jdbc.username");
String password = props.getProperty("jdbc.password");
return DriverManager.getConnection(url, username, password);
}
public static final int DEFAULT_WIDTH = 400;
public static final int DEFAULT_HEIGHT = 200;
private JButton previousButton;
private JButton nextButton;
private JButton deleteButton;
private JButton saveButton;
private DataPanel dataPanel;
private Component scrollPane;
private JComboBox tableNames;
private Properties props;
private CachedRowSet crs;
}
/**
* This panel displays the contents of a result set.
*/
class DataPanel extends JPanel
{
/**
* Constructs the data panel.
* @param rs the result set whose contents this panel displays
*/
public DataPanel(RowSet rs) throws SQLException
{
fields = new ArrayList<JTextField>();
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = 1;
gbc.gridheight = 1;
ResultSetMetaData rsmd = rs.getMetaData();
for (int i = 1; i <= rsmd.getColumnCount(); i++)
{
gbc.gridy = i - 1;
String columnName = rsmd.getColumnLabel(i);
gbc.gridx = 0;
gbc.anchor = GridBagConstraints.EAST;
add(new JLabel(columnName), gbc);
int columnWidth = rsmd.getColumnDisplaySize(i);
JTextField tb = new JTextField(columnWidth);
if (!rsmd.getColumnClassName(i).equals("java.lang.String"))
tb.setEditable(false);
fields.add(tb);
gbc.gridx = 1;
gbc.anchor = GridBagConstraints.WEST;
add(tb, gbc);
}
}
/**
* Shows a database row by populating all text fields with the column values.
*/
public void showRow(ResultSet rs) throws SQLException
{
for (int i = 1; i <= fields.size(); i++)
{
String field = rs.getString(i);
JTextField tb = (JTextField) fields.get(i - 1);
tb.setText(field);
}
}
/**
* Updates changed data into the current row of the row set
*/
public void setRow(RowSet rs) throws SQLException
{
for (int i = 1; i <= fields.size(); i++)
{
String field = rs.getString(i);
JTextField tb = (JTextField) fields.get(i - 1);
if (!field.equals(tb.getText()))
rs.updateString(i, tb.getText());
}
rs.updateRow();
}
private ArrayList<JTextField> fields;
}
//File: database.properties
#jdbc.drivers=org.apache.derby.jdbc.ClientDriver
jdbc.url=jdbc:derby://localhost:1527/COREJAVA;create=true
jdbc.username=dbuser
jdbc.password=secret
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