SWT Browser and Javascript

Sometime we feel the need of modifying SWT browser content dynamically. Using getText and modifying it is not the advisable way of changing HTML content. I will suggest you to use execute() method of org.eclipse.swt.browser.Browser. It allows you to fire javascripts on the DOM object of the page.

>> Example

Here in this code I am allowing the page to fully load and then looking for all the links item and then creating a red border around them.

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTError;
import org.eclipse.swt.browser.Browser;
import org.eclipse.swt.browser.LocationEvent;
import org.eclipse.swt.browser.LocationListener;
import org.eclipse.swt.browser.ProgressEvent;
import org.eclipse.swt.browser.ProgressListener;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.widgets.ToolBar;
import org.eclipse.swt.widgets.ToolItem;

public class BrowserTest 
{
 private static Browser browser;

 public static void main(String [] args) 
 {
  Display display = new Display();
  final Shell shell = new Shell(display);
  GridLayout gridLayout = new GridLayout();
  gridLayout.numColumns = 3;
  shell.setLayout(gridLayout);

  createBrowser(shell);

  browser.addProgressListener(new ProgressListener() 
  {
   public void changed(ProgressEvent event) {
   }
   public void completed(ProgressEvent event) {
    changeSomething();
   }
  });

  shell.open();
  browser.setUrl("http://google.com");

  while (!shell.isDisposed()) {
   if (!display.readAndDispatch())
    display.sleep();
  }
  display.dispose();
 }

 protected static void changeSomething() 
 {
  String s = "var allLinks = document.getElementsByTagName('a'); " +
    "for (var i=0, il=allLinks.length; i<il; i++) { " +
     "elm = allLinks[i]; elm.style.border = 'thin solid red';" +
    "}";

  System.out.println(browser.execute(s));
 }

 private static void createBrowser(Shell shell) 
 {
  ToolBar toolbar = new ToolBar(shell, SWT.NONE);
  ToolItem itemGo = new ToolItem(toolbar, SWT.PUSH);
  itemGo.setText("Go");

  GridData data = new GridData();
  data.horizontalSpan = 3;
  toolbar.setLayoutData(data);

  Label labelAddress = new Label(shell, SWT.NONE);
  labelAddress.setText("Address");

  final Text location = new Text(shell, SWT.BORDER);
  data = new GridData();
  data.horizontalAlignment = GridData.FILL;
  data.horizontalSpan = 2;
  data.grabExcessHorizontalSpace = true;
  location.setLayoutData(data);

  try {
   browser = new Browser(shell, SWT.NONE);
  } catch (SWTError e) {
   System.out.println("Could not instantiate Browser: " + e.getMessage());
   //display.dispose();
   return;
  }
  data = new GridData(SWT.FILL, SWT.FILL, true, true);
  data.horizontalSpan = 3;
  browser.setLayoutData(data);

  /* event handling */
  Listener listener = new Listener() 
  {
   public void handleEvent(Event event) 
   {
    ToolItem item = (ToolItem)event.widget;
    String string = item.getText();
    if (string.equals("Go")) browser.setUrl(location.getText());
   }
  };

  browser.addLocationListener(new LocationListener() {
   public void changed(LocationEvent event) {
    if (event.top) location.setText(event.location);
   }
   public void changing(LocationEvent event) {
   }
  });


  itemGo.addListener(SWT.Selection, listener);
  location.addListener(SWT.DefaultSelection, new Listener() {
   public void handleEvent(Event e) {
    browser.setUrl(location.getText());
   }
  });  
 }
}

>>Output

>> Further Reading

1. Eclipse Article
   
2. SWT Snippets