RCP Tree Viewer

here is some info about JFace TreeViewer.

The Model is worked with MVC

• Viewer: TreeViewer, LabelProvider


• Model: Your own model, ContentProvider. The Objects should be Singleton


• Control: create the Model, change the Model, refresh Viewer

Create a RCP Application (for tutorials see: Vogella).

Add a view: Manifest -> Extensions -> All Extensions -> Add ( views)
give an ID, name and create a class.

At first create the Model. The Model is a tree with root and nodes.

root
\
 node
 \node
\
node
\node
\node

This example create a tree of hosts an commands for each host.

The root class. This object should be a singleton and have access to hostnames objects.
The hostnames object should have access to commands objects.

            RootNames
         /      |       \
    /           |           \
  host1       host2        host3
 /  |  \       |   \          |
c1  c2  c3    c1   c2         command1

create package: xxx.model

The model package will be have: RootNames, HostsNames and Commands class models.

public class RootNames {
 private static RootNames root=null;
 public String name;
 public ArrayList children;

 private RootNames(String name) {
  this.name=name;
  children = new ArrayList();
  
 }
 
 public static RootNames getRootNames(String name) {
  if(root!=null)
   return root;
  RootNames r = new RootNames(name);
  root=r;
  return root;
 }

        public String toString() {
  return name;
 }
}

RootNames is a singleton, has only a name and children of HostsNames. For simplicity we do the access public. Thus we don't need implement setter or getter.

Then we implement following help methods in RootNames:

 public void addChild(HostsNames child) {
  children.add(child);
  child.parent = this;
 }
 
 public void removeChild(HostsNames child) {
  children.remove(child);
  child.parent = null;
 }
 
 public HostsNames[] getChildren() {
  return (HostsNames[]) children.toArray(new HostsNames[children.size()]);
 }
 
 public boolean hasChildren() {
  return children.size()>0;
 }

- add/removeChild() add/remove a child in a list and set/unset the parent of child.
- getChildren() return an array of objects of children. Here a HostsNames array.

HostsNames:

public class HostsNames {
 public String name;
 public String host;
 public RootNames parent;
 public ArrayList children;
 
 public HostsNames(String name, String host) {
  this.name = name;
  this.host = host;
  children = new ArrayList();
 }
 
 public void addChild(Commandos child) {
  children.add(child);
  child.parent = this;
 }
 
 public void removeChild(Commandos child) {
  children.remove(child);
  child.parent = null;
 }
 
 public Commandos[] getChildren() {
  return (Commandos[]) children.toArray(new Commandos[children.size()]);
 }
 
 public boolean hasChildren() {
  return children.size()>0;
 }

        public String toString() {
  return name;
 }
}

HostsNames: have a name, hostname, parent to root and children of Commandos. And helpers for Children.

Commandos:

public class Commandos {
 public String name;
 public String commando;
 public HostsNames parent;
 
 public Commandos(String name, String commando)  {
  this.name = name;
  this.commando = commando;
 }

        public String toString() {
  return name;
 }
}

Commandos have name, commando and reference to HostsNames via parent.


Implement Provider:

create package xxx.provider

public class ViewLabelProvider extends LabelProvider {
 
 public String getText(Object obj) {
  return obj.toString();
 }
 
 public Image getImage(Object obj) {
  String imageKey = ISharedImages.IMG_OBJ_ELEMENT;
  if (obj instanceof HostsNames)
     imageKey = ISharedImages.IMG_OBJ_FOLDER;
  return PlatformUI.getWorkbench().getSharedImages().getImage(imageKey);
 }
}

The Label Provider is a View in MVC. it give the name and the image of the Tree back, based on model.

Create a View Content Provider with implemented Interfaces: IStructuredContentProvider and ITreeContentProvider.

public class ViewContentProvider implements IStructuredContentProvider, ITreeContentProvider {

 @Override
 public Object[] getElements(Object inputElement) {
  return null;
 }

 @Override
 public void dispose() {  
 }

 @Override
 public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
 }

 @Override
 public Object[] getChildren(Object parentElement) {
  return null;
 }

 @Override
 public Object getParent(Object element) {
  return null;
 }

 @Override
 public boolean hasChildren(Object element) {
  return false;
 }
}

The Content Provider is the model part of MVC. It provide how the TreeViewer can access the model.
following methods must be implemented: getElements(), getParent(), getChildren(), hasChildren().

Implementation:

 @Override
 public Object[] getElements(Object parent) {
  return getChildren(parent);
 }
 @Override
 public Object[] getChildren(Object parent) {
  if (parent instanceof RootNames) {
   return ((RootNames)parent).getChildren();
  }
  if (parent instanceof HostsNames) {
   return ((HostsNames)parent).getChildren();
  }
  return new Object[0];
 }

 @Override
 public Object getParent(Object child) {
  if (child instanceof HostsNames) {
   return ((HostsNames)child).parent;
  }
  if (child instanceof Commandos) {
   return ((Commandos)child).parent;
  }
  return null;
 }

 @Override
 public boolean hasChildren(Object element) {
  if (element instanceof RootNames)
   return ((RootNames)element).hasChildren();
  if (element instanceof HostsNames)
   return ((HostsNames)element).hasChildren();
  return false;
 }

getElements and getChildren is here the same.

getChildren() return for RootNames or HostsNames his children list as an array. The same is do getParent() and hasChildren().


Now set the ViewPart:

 private TreeViewer viewer;
 private RootNames root;
 
 @Override
 public void createPartControl(Composite parent) {
  viewer = new TreeViewer(parent, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER);
  viewer.setContentProvider(new ViewContentProvider());
  viewer.setLabelProvider(new ViewLabelProvider());
  root=ModelCreator.createModel();
  viewer.setInput(root);
 }

Create the TreeViewer.
Set our Content and Label Provider. Call the Model Creator.

ModelCreator:

public class ModelCreator {
 
 public static RootNames createModel() {
  RootNames root = RootNames.getRootNames("root");
  
  HostsNames hn = new HostsNames("localhost", "localhost");
  root.addChild(hn);
  hn.addChild(new Commandos("syslog", "syslog"));
  hn.addChild(new Commandos("top", "top -d 1"));
  
  hn = new HostsNames("134.108.68.107", "134.108.68.107");
  root.addChild(hn);
  hn.addChild(new Commandos("syslog", "syslog"));
  hn.addChild(new Commandos("top", "top -d 1"));
  
  return root;
 }
}

createModel() create a root with two hostnames and his commandos.

Then we must set the view in perspective

String editorArea = layout.getEditorArea();
  layout.setEditorAreaVisible(false);
  
  layout.addStandaloneView(ViewPart1.ID,  false, IPageLayout.LEFT, 0.95f, editorArea);
  
  layout.getViewLayout(ViewPart1.ID).setCloseable(false);

to add some context to the tree (here an example with a Command:

public class CommandAdd extends AbstractHandler {

 @Override
 public Object execute(ExecutionEvent event) throws ExecutionException {
  System.out.println("blub");
  RootNames root = ViewPart1.getTreeRoot();
  System.out.println("blub: "+root);
  
  HostsNames hn = new HostsNames("212.40.32.55", "212.40.32.55");
  root.addChild(hn);
  hn.addChild(new Commandos("syslog", "syslog"));
  hn.addChild(new Commandos("top", "top -d 1"));
  hn.addChild(new Commandos("network", "network"));

  ViewPart1.getTreeViewer().refresh();
  
  return null;
 }
}

simple get the singleton and add some childs. Then refresh the view.