📄 screenscraping.java
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// Tutorial 23: ScreenScraping.java
// Search an HTML code String for an item and display its price
// converted from euros to American dollars.
import java.awt.*;
import java.awt.event.*;
import java.text.*;
import javax.swing.*;
public class ScreenScraping extends JFrame
{
// JLabel and JComboBox for item names
private JLabel itemJLabel;
private JComboBox itemJComboBox;
// JLabel and JTextField for conversion rate
private JLabel rateJLabel;
private JTextField rateJTextField;
// JLabel and JTextField for item price
private JLabel priceJLabel;
private JTextField priceJTextField;
// JButton to search HTML code for item price
private JButton searchJButton;
// JLabel and JTextArea for HTML code
private JLabel sourceJLabel;
private JTextArea sourceJTextArea;
// items that can be found in HTML code
private String[] items = { "Antique Rocking Chair",
"Silver Teapot", "Gold Pocket Watch" };
// small piece of HTML code containing items and prices
private String htmlText = "<HTML><BODY><TABLE>"
+ "<TR><TD>Antique Rocking Chair</TD>"
+ "<TD>€82.67</TD></TR>"
+ "<TR><TD>Silver Teapot</TD>"
+ "<TD>€64.55</TD></TR>"
+ "<TR><TD>Gold Pocket Watch</TD>"
+ "<TD>€128.83</TD></TR>"
+ "</TABLE></BODY></HTML>";
// no-argument constructor
public ScreenScraping()
{
createUserInterface();
}
// create and position GUI components; register event handlers
private void createUserInterface()
{
// get content pane for attaching GUI components
Container contentPane = getContentPane();
// enable explicit positioning of GUI components
contentPane.setLayout( null );
// set up itemJLabel
itemJLabel = new JLabel();
itemJLabel.setBounds( 8, 16, 40, 21 );
itemJLabel.setText( "Item:" );
contentPane.add( itemJLabel );
// set up itemJComboBox
itemJComboBox = new JComboBox( items );
itemJComboBox.setBounds( 56, 16, 184, 21 );
contentPane.add( itemJComboBox );
// set up rateJLabel
rateJLabel = new JLabel();
rateJLabel.setBounds( 8, 48, 40, 21 );
rateJLabel.setText( "Rate:" );
contentPane.add( rateJLabel );
// set up rateJTextField
rateJTextField = new JTextField();
rateJTextField.setBounds( 56, 48, 184, 21 );
rateJTextField.setHorizontalAlignment( JTextField.RIGHT );
contentPane.add( rateJTextField );
// set up priceJLabel
priceJLabel = new JLabel();
priceJLabel.setBounds( 8, 80, 40, 21 );
priceJLabel.setText( "Price:" );
contentPane.add( priceJLabel );
// set up priceJTextField
priceJTextField = new JTextField();
priceJTextField.setBounds( 56, 80, 96, 21 );
priceJTextField.setHorizontalAlignment( JTextField.CENTER );
priceJTextField.setEditable( false );
contentPane.add( priceJTextField );
// set up searchJButton
searchJButton = new JButton();
searchJButton.setBounds( 160, 80, 80, 23 );
searchJButton.setText( "Search" );
contentPane.add( searchJButton );
searchJButton.addActionListener(
new ActionListener() // anonymous inner class
{
// event handler called when searchJButton is pressed
public void actionPerformed( ActionEvent event )
{
searchJButtonActionPerformed( event );
}
} // end anonymous inner class
); // end call to addActionListener
// set up sourceJLabel
sourceJLabel = new JLabel();
sourceJLabel.setBounds( 8, 112, 48, 16 );
sourceJLabel.setText( "Source:" );
contentPane.add( sourceJLabel );
// set up sourceJTextArea
sourceJTextArea = new JTextArea();
sourceJTextArea.setBounds( 8, 136, 232, 105 );
sourceJTextArea.setText( htmlText );
sourceJTextArea.setLineWrap( true );
contentPane.add( sourceJTextArea );
// set properties of application's window
setTitle( "Screen Scraping" ); // set title bar string
setSize( 259, 278 ); // set window size
setVisible( true ); // display window
} // end method createUserInterface
// find and display price substring
private void searchJButtonActionPerformed( ActionEvent event )
{
// get rate
String rate = rateJTextField.getText();
// rate is an empty string
if ( rate.equals( "" ) )
{
JOptionPane.showMessageDialog( null,
"Please enter conversion rate first.",
"Missing Rate", JOptionPane.WARNING_MESSAGE );
return; // exit method
}
// search for location of item and price
String selectedItem =
( String ) itemJComboBox.getSelectedItem();
int itemLocation = htmlText.indexOf( selectedItem );
int priceBegin = htmlText.indexOf( "€", itemLocation );
int priceEnd = htmlText.indexOf( "</TD>", priceBegin );
// store price found in double price
String priceText = htmlText.substring(
priceBegin + 6, priceEnd );
double price = Double.parseDouble( priceText );
// convert price from euros to dollars
double conversionRate = Double.parseDouble(
rateJTextField.getText() );
price *= conversionRate;
// display price of item in priceJTextField
DecimalFormat dollars = new DecimalFormat( "$0.00" );
priceJTextField.setText( dollars.format( price ) );
} // end method searchJButtonActionPerformed
// main method
public static void main( String args[] )
{
ScreenScraping application = new ScreenScraping();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
} // end method main
} // end class ScreenScraping
/**************************************************************************
* (C) Copyright 1992-2004 by Deitel & Associates, Inc. and *
* Pearson Education, Inc. All Rights Reserved. *
* *
* DISCLAIMER: The authors and publisher of this book have used their *
* best efforts in preparing the book. These efforts include the *
* development, research, and testing of the theories and programs *
* to determine their effectiveness. The authors and publisher make *
* no warranty of any kind, expressed or implied, with regard to these *
* programs or to the documentation contained in these books. The authors *
* and publisher shall not be liable in any event for incidental or *
* consequential damages in connection with, or arising out of, the *
* furnishing, performance, or use of these programs. *
**************************************************************************/⌨️ 快捷键说明
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