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/*
Java Swing, 2nd Edition
By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole
ISBN: 0-596-00408-7
Publisher: O'Reilly
*/
// DatabaseTest.java
//Let's try to make one of these databases work with a JTable for ouptut.
//
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
import java.util.Vector;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.table.AbstractTableModel;
public class DatabaseTest extends JFrame {
JTextField hostField;
JTextField queryField;
QueryTableModel qtm;
public DatabaseTest() {
super("Database Test Frame");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(350, 200);
qtm = new QueryTableModel();
JTable table = new JTable(qtm);
JScrollPane scrollpane = new JScrollPane(table);
JPanel p1 = new JPanel();
p1.setLayout(new GridLayout(3, 2));
p1.add(new JLabel("Enter the Host URL: "));
p1.add(hostField = new JTextField());
p1.add(new JLabel("Enter your query: "));
p1.add(queryField = new JTextField());
p1.add(new JLabel("Click here to send: "));
JButton jb = new JButton("Search");
jb.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
qtm.setHostURL(hostField.getText().trim());
qtm.setQuery(queryField.getText().trim());
}
});
p1.add(jb);
getContentPane().add(p1, BorderLayout.NORTH);
getContentPane().add(scrollpane, BorderLayout.CENTER);
}
public static void main(String args[]) {
DatabaseTest tt = new DatabaseTest();
tt.setVisible(true);
}
}
//QueryTableModel.java
//A basic implementation of the TableModel interface that fills out a Vector of
//String[] structures from a query's result set.
//
class QueryTableModel extends AbstractTableModel {
Vector cache; // will hold String[] objects . . .
int colCount;
String[] headers;
Connection db;
Statement statement;
String currentURL;
public QueryTableModel() {
cache = new Vector();
new gsl.sql.driv.Driver();
}
public String getColumnName(int i) {
return headers[i];
}
public int getColumnCount() {
return colCount;
}
public int getRowCount() {
return cache.size();
}
public Object getValueAt(int row, int col) {
return ((String[]) cache.elementAt(row))[col];
}
public void setHostURL(String url) {
if (url.equals(currentURL)) {
// same database, we can leave the current connection open
return;
}
// Oops . . . new connection required
closeDB();
initDB(url);
currentURL = url;
}
// All the real work happens here; in a real application,
// we'd probably perform the query in a separate thread.
public void setQuery(String q) {
cache = new Vector();
try {
// Execute the query and store the result set and its metadata
ResultSet rs = statement.executeQuery(q);
ResultSetMetaData meta = rs.getMetaData();
colCount = meta.getColumnCount();
// Now we must rebuild the headers array with the new column names
headers = new String[colCount];
for (int h = 1; h <= colCount; h++) {
headers[h - 1] = meta.getColumnName(h);
}
// and file the cache with the records from our query. This would
// not be
// practical if we were expecting a few million records in response
// to our
// query, but we aren't, so we can do this.
while (rs.next()) {
String[] record = new String[colCount];
for (int i = 0; i < colCount; i++) {
record[i] = rs.getString(i + 1);
}
cache.addElement(record);
}
fireTableChanged(null); // notify everyone that we have a new table.
} catch (Exception e) {
cache = new Vector(); // blank it out and keep going.
e.printStackTrace();
}
}
public void initDB(String url) {
try {
db = DriverManager.getConnection(url);
statement = db.createStatement();
} catch (Exception e) {
System.out.println("Could not initialize the database.");
e.printStackTrace();
}
}
public void closeDB() {
try {
if (statement != null) {
statement.close();
}
if (db != null) {
db.close();
}
} catch (Exception e) {
System.out.println("Could not close the current connection.");
e.printStackTrace();
}
}
}
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