Swt jface 提供了virtual table 和 virtual tree

转自: http://www.blogjava.net/cherishchen/archive/2007/06/26/126271.aspx

使用虚拟表和虚拟树的确可以很大程度地提供UI界面的性能,尤其是在大数据量的情况下，对于TableViewer使用虚拟表很简单，只要在创建TableViewer的时候指定SWT.VIRTUAL即可

<!----> tableViewer = new TableViewer(container, SWT.FULL_SELECTION
| SWT.BORDER | SWT.HIDE_SELECTION | SWT.VIRTUAL);

在以前的版本， TableViewer要使用virtual table的时候，需要实现ILazyContentProvider接口，但是目前好像是不用了，下面附上两个eclipse社区提供的例子

Snippet030VirtualLazyTableViewer.java,使用的是实现 ILazyContentProvider接口

<!----> import org.eclipse.jface.viewers.ILazyContentProvider;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

/**
* A simple TableViewer to demonstrate usage of an ILazyContentProvider. You can compare this snippet to the Snippet029VirtualTableViewer
* to see the small but needed difference.
*
* @author Tom Schindl <[email protected]>
*
*/
public class Snippet030VirtualLazyTableViewer {
private class MyContentProvider implements IStructuredContentProvider, ILazyContentProvider {
private TableViewer viewer;
private MyModel[] elements;

public MyContentProvider(TableViewer viewer) {
this .viewer = viewer;
}

/* (non-Javadoc)
* @see org.eclipse.jface.viewers.IStructuredContentProvider#getElements(java.lang.Object)
*/
public Object[] getElements(Object inputElement) {
return elements;
}

/* (non-Javadoc)
* @see org.eclipse.jface.viewers.IContentProvider#dispose()
*/
public void dispose() {

}

/* (non-Javadoc)
* @see org.eclipse.jface.viewers.IContentProvider#inputChanged(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object)
*/
public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
this .elements = (MyModel[])newInput;
}

public void updateElement( int index) {
viewer.replace(elements[index], index);
}

}

public class MyModel {
public int counter;

public MyModel( int counter) {
this .counter = counter;
}

public String toString() {
return " Item " + this .counter;
}
}

public Snippet030VirtualLazyTableViewer(Shell shell) {
final TableViewer v = new TableViewer(shell,SWT.VIRTUAL);
v.setLabelProvider( new LabelProvider());
v.setContentProvider( new MyContentProvider(v));
v.setUseHashlookup( true );
MyModel[] model = createModel();
v.setInput(model);
v.setItemCount(model.length); // This is the difference when using a ILazyContentProvider

v.getTable().setLinesVisible( true );
}

private MyModel[] createModel() {
MyModel[] elements = new MyModel[ 10000 ];

for ( int i = 0 ; i < 10000 ; i ++ ) {
elements[i] = new MyModel(i);
}

return elements;
}

/**
* @param args
*/
public static void main(String[] args) {
Display display = new Display ();
Shell shell = new Shell(display);
shell.setLayout( new FillLayout());
new Snippet030VirtualLazyTableViewer(shell);
shell.open ();

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

display.dispose ();

}

}

Snippet029VirtualTableViewer.java 更加方便，直接指定SWT.VIRTUAL即可

<!----> import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

/**
* A simple TableViewer to demonstrate the usage of a standard content provider
* with a virtual table
*
* @author Tom Schindl <[email protected]>
*
*/
public class Snippet029VirtualTableViewer {
private class MyContentProvider implements IStructuredContentProvider {
private MyModel[] elements;

/*
* (non-Javadoc)
*
* @see org.eclipse.jface.viewers.IStructuredContentProvider#getElements(java.lang.Object)
*/
public Object[] getElements(Object inputElement) {
return elements;
}

/*
* (non-Javadoc)
*
* @see org.eclipse.jface.viewers.IContentProvider#dispose()
*/
public void dispose() {

}

/*
* (non-Javadoc)
*
* @see org.eclipse.jface.viewers.IContentProvider#inputChanged(org.eclipse.jface.viewers.Viewer,
* java.lang.Object, java.lang.Object)
*/
public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
this .elements = (MyModel[]) newInput;
}
}

public class MyModel {
public int counter;

public MyModel( int counter) {
this .counter = counter;
}

public String toString() {
return " Item " + this .counter;
}
}

public Snippet029VirtualTableViewer(Shell shell) {
long time1 = System.currentTimeMillis();
final TableViewer v = new TableViewer(shell,SWT.VIRTUAL);
v.setLabelProvider( new LabelProvider());
v.setContentProvider( new MyContentProvider());
v.setUseHashlookup( true );
MyModel[] model = createModel();
v.setInput(model);

v.getTable().setLinesVisible( true );
System.out.println(System.currentTimeMillis() - time1);
}

private MyModel[] createModel() {
MyModel[] elements = new MyModel[ 10000 ];

for ( int i = 0 ; i < 10000 ; i ++ ) {
elements[i] = new MyModel(i);
}

return elements;
}

/**
* @param args
*/
public static void main(String[] args) {
Display display = new Display();
Shell shell = new Shell(display);
shell.setLayout( new FillLayout());
new Snippet029VirtualTableViewer(shell);
shell.open();

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

display.dispose();

}

}