printingbooks.java

这个软件是一个图书管理系统

//import the packages for using the classes in them into the program
import java.sql.*;
import java.awt.*;
import java.util.*;
import java.awt.print.*;
import javax.swing.*;

public class printingBooks extends JInternalFrame implements Printable {
	/***************************************************************************
	 ***      declaration of the private variables used in the program       ***
	 ***************************************************************************/
	
	//for setting the connection and statement
	private Connection connection = null;
	private Statement statement   = null;
	private ResultSet resultset   = null;
	
	//for creating the text area
	private JTextArea textArea = new JTextArea();
	//for creating the vector to use it in the print
	private Vector lines;
	public static final int TAB_SIZE = 10;
	
	//constructor of JLibrary
	public printingBooks(String query) {
		super("Printing Books", false, true, false, true);
		//for getting the graphical user interface components display area
		Container cp = getContentPane();
		//for setting the font
		textArea.setFont(new Font("Terminal", Font.PLAIN, 10));
		//for adding the textarea to the container
		cp.add(textArea);
		try {
			Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
		}
		catch(ClassNotFoundException ea) {
			System.out.println(ea.toString());
		}
		catch(Exception e) {
			System.out.println(e.toString());
		}
		/***************************************************************
		 * for making the connection,creating the statement and update *
		 * the table in the database. After that,closing the statmenet *
		 * and connection. There is catch block SQLException for error *
		 ***************************************************************/
		try {
			connection = DriverManager.getConnection("jdbc:odbc:JLibrary");
			statement  = connection.createStatement();
			resultset  = statement.executeQuery(query);
			while(resultset.next()) {
				textArea.append(resultset.getString("Subject") + "\t" + resultset.getString("Title") + "\t" +
								resultset.getString("Author")  + "\t" + resultset.getString("ISBN")  + "\n");
			}
			resultset.close();
			statement.close();
			connection.close();
		}
		catch(SQLException SQLe) {
			System.out.println(SQLe.toString());
		}
		//for setting the visible to true
		setVisible(true);
		//to show the frame
		pack();
	}
	public int print(Graphics pg,PageFormat pageFormat,int pageIndex) throws PrinterException {
		pg.translate((int)pageFormat.getImageableX(),(int)pageFormat.getImageableY());
		int wPage = (int)pageFormat.getImageableWidth();
		int hPage = (int)pageFormat.getImageableHeight();
		pg.setClip(0, 0, wPage, hPage);

		pg.setColor(textArea.getBackground());
		pg.fillRect(0, 0, wPage, hPage);
		pg.setColor(textArea.getForeground());

		Font font = textArea.getFont();
		pg.setFont(font);
		FontMetrics fm = pg.getFontMetrics();
		int hLine = fm.getHeight();

		if(lines == null)
			lines = getLines(fm, wPage);

		int numLines = lines.size();
		int linesPerPage = Math.max(hPage / hLine, 1);
		int numPages = (int)Math.ceil((double)numLines / (double)linesPerPage);
		if(pageIndex >= numPages) {
			lines = null;
			return NO_SUCH_PAGE;
		}
		int x = 0;
		int y = fm.getAscent();
		int lineIndex = linesPerPage*pageIndex;
		while(lineIndex < lines.size() && y < hPage) {
			String str = (String)lines.get(lineIndex);
			pg.drawString(str, x, y);
			y += hLine;
			lineIndex++;
		}
		return PAGE_EXISTS;
	}
	protected Vector getLines(FontMetrics fm, int wPage) {
		Vector v = new Vector();
		
		String text = textArea.getText();
		String prevToken = "";
		StringTokenizer st = new StringTokenizer(text, "\n\r", true);
		while(st.hasMoreTokens()) {
			String line = st.nextToken();
			if(line.equals("\r"))
				continue;
			// StringTokenizer will ignore empty lines, so it's a bit tricky to get them...
			if(line.equals("\n") && prevToken.equals("\n"))
				v.add("");
			prevToken = line;
			if(line.equals("\n"))
				continue;

			StringTokenizer st2 = new StringTokenizer(line, " \t", true);
			String line2 = "";
			while(st2.hasMoreTokens()) {
				String token = st2.nextToken();
				if(token.equals("\t")) {
					int numSpaces = TAB_SIZE - line2.length()%TAB_SIZE;
					token = "";
					for(int k = 0; k < numSpaces; k++)
						token += " ";
				}
				int lineLength = fm.stringWidth(line2 + token);
				if(lineLength > wPage && line2.length() > 0) {
					v.add(line2);
					line2 = token.trim();
					continue;
				}
				line2 += token;
			}
			v.add(line2);
		}
		return v;
	}
}