DatabaseTest.java Source code

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Here is the source code for DatabaseTest.java

Source

/*
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();
        }
    }
}