Posted on 2008-01-07 17:16
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Java插件开发
这一节我们来介绍如何在编辑器中移动活动，改变活动的大小和删除活动，在流程控制器中已经安装的策略WorkflowProcessXYLayoutEditPolicy，可以接受移动活动和改变活动大小的请求，但不能接受删除活动的请求，要处理删除活动的请求，必须在活动控制器中安装策略。
我们还是先来看WorkflowProcessXYLayoutEditPolicy这个类，要实现改变活动大小和位置的功能，应该覆盖父类的createChangeConstraintCommand方法，具体代码如下：
/** *//**ResizeorMoveAbstractActivityintheWorkflowProcessEditor*/
protected Command createChangeConstraintCommand(ChangeBoundsRequest request, EditPart child, Object constraint) 
{
if(child instanceof AbstractActivityEditPart && constraint instanceof Rectangle){
//return a command that can move and/or resize a AbstractActivity
returnnew AbstractActivitySetConstraintCommand(
(AbstractActivity)child.getModel(), request, (Rectangle) constraint);
}
returnsuper.createChangeConstraintCommand(request, child, constraint);
}
在这个方法中，我们创建一个AbstractActivitySetConstraintCommand命令，用这个命令来修改活动的位置，大小属性，这个命令的具体代码如下：
package com.example.workflow.commands;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.gef.RequestConstants;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.requests.ChangeBoundsRequest;
import com.example.workflow.model.AbstractActivity;
/** *//**
* A command to resize and/or move a shape.
* The command can be undone or redone.
*/
public class AbstractActivitySetConstraintCommand extends Command{
/** *//** Stores the new size and location. */
private final Rectangle newBounds;
/** *//** Stores the old size and location. */
private Rectangle oldBounds;
/** *//** A request to move/resize an edit part. */
private final ChangeBoundsRequest request;
/** *//** AbstractActivity to manipulate. */
private final AbstractActivity abstractActivity;
/** *//**
* Create a command that can resize and/or move a AbstractActivity.
* @param abstractActivity the AbstractActivity to manipulate
* @param req the move and resize request
* @param newBounds the new size and location
* @throws IllegalArgumentException if any of the parameters is null
*/
public AbstractActivitySetConstraintCommand(AbstractActivity abstractActivity,
ChangeBoundsRequest req,Rectangle newBounds){
if (abstractActivity == null || req == null || newBounds == null) {
throw new IllegalArgumentException();
}
this.abstractActivity = abstractActivity;
this.request = req;
this.newBounds = newBounds.getCopy();
setLabel("move / resize");
}
/**//* (non-Javadoc)
* @see org.eclipse.gef.commands.Command#canExecute()
*/
public boolean canExecute() {
Object type = request.getType();
// make sure the Request is of a type we support:
return (RequestConstants.REQ_MOVE.equals(type)
|| RequestConstants.REQ_MOVE_CHILDREN.equals(type)
|| RequestConstants.REQ_RESIZE.equals(type)
|| RequestConstants.REQ_RESIZE_CHILDREN.equals(type));
}
/**//* (non-Javadoc)
* @see org.eclipse.gef.commands.Command#execute()
*/
public void execute() {
oldBounds = new Rectangle(abstractActivity.getLocation(), abstractActivity.getSize());
redo();
}
/**//* (non-Javadoc)
* @see org.eclipse.gef.commands.Command#redo()
*/
public void redo() {
abstractActivity.setSize(newBounds.getSize());
abstractActivity.setLocation(newBounds.getLocation());
}
/**//* (non-Javadoc)
* @see org.eclipse.gef.commands.Command#undo()
*/
public void undo() {
abstractActivity.setSize(oldBounds.getSize());
abstractActivity.setLocation(oldBounds.getLocation());
}
}
我们知道修改了活动的大小，位置属性之后，活动模型会通知控制器它的LOCATION_PROP，SIZE_PROP发生变化，这可在模型的定义中看到：
publicvoid setLocation(Point newLocation) {
if (newLocation == null) {
thrownew IllegalArgumentException();
}
location.setLocation(newLocation);
firePropertyChange(LOCATION_PROP, null, location);
}
publicvoid setSize(Dimension newSize) {
if (newSize != null) {
size.setSize(newSize);
firePropertyChange(SIZE_PROP, null, size);
}
}
活动控制器AbstractActivityEditPart应该根据这些属性的变化来刷新视图，代码如下：
publicvoid propertyChange(PropertyChangeEvent evt) {
String prop = evt.getPropertyName();
if(AbstractActivity.SIZE_PROP.equals(prop)
||AbstractActivity.LOCATION_PROP.equals(prop)){
refreshVisuals();
}
}
而refreshVisuals()方法我们已经在前面实现好了，这样我们运行项目，就可以改变活动的位置和大小了，
接下来，我们介绍如何在编辑器中删除活动，要实现这功能，应该在活动控制器AbstractActivityEditPart中安装能接受删除活动请求的策略，代码如下：
protectedvoid createEditPolicies() {
//allow removal of the associated model element
installEditPolicy(EditPolicy.COMPONENT_ROLE, new AbstractActivityComponentEditPolicy());
}
策略AbstractActivityComponentEditPolicy的代码如下：
package com.example.workflow.policy;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.editpolicies.ComponentEditPolicy;
import org.eclipse.gef.requests.GroupRequest;
import com.example.workflow.commands.AbstractActivityDeleteCommand;
import com.example.workflow.model.AbstractActivity;
import com.example.workflow.model.WorkflowProcess;
public class AbstractActivityComponentEditPolicy extends ComponentEditPolicy{
protected Command createDeleteCommand(GroupRequest deleteRequest) {
Object parent = getHost().getParent().getModel();
Object child = getHost().getModel();
if(parent instanceof WorkflowProcess && child instanceof AbstractActivity){
return new AbstractActivityDeleteCommand((WorkflowProcess)parent,(AbstractActivity)child);
}
return super.createDeleteCommand(deleteRequest);
}
}
这个策略继承了ComponentEditPolicy类，并且覆盖了createDeleteCommand方法，在这个方法中，我们创建了AbstractActivityDeleteCommand命令，这个命令完成从流程模型中删除当前活动模型，我们知道在活动模型中，还维护着输入转移和输出转移两个列表，而转移对象中又维护着转移的起始活动和终止活动，由于删除了活动，转移就成了只有源点或者只要目标点，因此，我们还应该从还维护着这些转移的活动中删除这些转移，该命令的代码如下：
package com.example.workflow.commands;
import java.util.Iterator;
import java.util.List;
import org.eclipse.gef.commands.Command;
import com.example.workflow.model.AbstractActivity;
import com.example.workflow.model.Transition;
import com.example.workflow.model.WorkflowProcess;
/** *//**
* A command to remove a AbstractActivity from its parent.
* The command can be undone or redone.
*/
public class AbstractActivityDeleteCommand extends Command{
/** *//** AbstractActivity to remove. */
private final AbstractActivity child;
/** *//** WorkflowProcess to remove from. */
private final WorkflowProcess parent;
/** *//** Holds a copy of the outgoing transitions of child. */
private List sourceTransitions;
/** *//** Holds a copy of the incoming transitions of child. */
private List targetTransitions;
/** *//** True, if child was removed from its parent. */
private boolean wasRemoved;
/** *//**
* Create a command that will remove the AbstractActivity from its parent.
* @param parent the WorkflowProcess containing the child
* @param child the AbstractActivity to remove
* @throws IllegalArgumentException if any parameter is null
*/
public AbstractActivityDeleteCommand(WorkflowProcess parent, AbstractActivity child) {
if (parent == null || child == null) {
throw new IllegalArgumentException();
}
setLabel("activity deletion");
this.parent = parent;
this.child = child;
}
/** *//**
* Reconnects a List of Transitions with their previous endpoints.
* @param transitions a non-null List of connections
*/
private void addConnections(List transitions) {
for (Iterator iter = transitions.iterator(); iter.hasNext();) {
Transition tran = (Transition) iter.next();
tran.reconnect();
}
}
/**//* (non-Javadoc)
* @see org.eclipse.gef.commands.Command#canUndo()
*/
public boolean canUndo() {
return wasRemoved;
}
/**//* (non-Javadoc)
* @see org.eclipse.gef.commands.Command#execute()
*/
public void execute() {
// store a copy of incoming & outgoing transitions before proceeding
sourceTransitions = child.getSourceTransitions();
targetTransitions = child.getTargetTransitions();
redo();
}
/**//* (non-Javadoc)
* @see org.eclipse.gef.commands.Command#redo()
*/
public void redo() {
// remove the child and disconnect its connections
wasRemoved = parent.removeChild(child);
if (wasRemoved) {
removeTransitions(sourceTransitions);
removeTransitions(targetTransitions);
}
}
/** *//**
* Disconnects a List of Transitions from their endpoints.
* @param transitions a non-null List of transitions
*/
private void removeTransitions(List transitions) {
for (Iterator iter = transitions.iterator(); iter.hasNext();) {
Transition tran = (Transition) iter.next();
tran.disconnect();
}
}
/**//* (non-Javadoc)
* @see org.eclipse.gef.commands.Command#undo()
*/
public void undo() {
// add the child and reconnect its transitions
if (parent.addChild(child)) {
addConnections(sourceTransitions);
addConnections(targetTransitions);
}
}
}
这个命令中从流程模型中删除了活动模型，流程模型通知控制器，它的CHILD_REMOVED_PROP属性发生了变化，要控制器刷新它维护的活动集。
要实现删除操作，我们必须通过删除菜单或者键盘的删除键，但现在编辑器还不支持这些功能，无论是通过删除菜单还是删除键，都是执行了一个Action，由这个Action来执行我们定义的删除命令（关于Action和菜单的实现，我们在以后会讲），这儿只介绍如何让编辑器支持键盘操作，要实现键盘操作，在WorkflowProcessEditor类中定义一个KeyHandler 类型的成员变量sharedKeyHandler;
接下来定义一个方法：
protected KeyHandler getCommonKeyHandler() {
if (sharedKeyHandler == null) {
sharedKeyHandler = new KeyHandler();
sharedKeyHandler.put(
KeyStroke.getPressed(SWT.DEL, 127, 0),
getActionRegistry().getAction(ActionFactory.DELETE.getId()));
}
returnsharedKeyHandler;
}
该方法的作用是定义我们支持的键名，上面定义了删除键，并且把这个键和删除Action邦定，当按删除键，就执行对应的Action，sharedKeyHandler可以供编辑器和大纲视图公用，关于大纲视图在以后会讲。
接下来还需要在编辑器视图中注册这些这些公共键，代码如下：
protectedvoid configureGraphicalViewer() {
super.configureGraphicalViewer();
GraphicalViewer viewer = getGraphicalViewer();
viewer.setEditPartFactory(new WorkflowProcessEditPartFactory());
viewer.setRootEditPart(new ScalableFreeformRootEditPart());
getGraphicalViewer().setKeyHandler(new GraphicalViewerKeyHandler(getGraphicalViewer())
.setParent(getCommonKeyHandler()));
}
这样运行项目，我们就可以用键盘的删除键来删除活动了，我们注意到无论我们向编辑器中增加活动，还是删除活动，编辑器的状态始终没变，不像其它编辑器修改之后，提示编辑器处于未保存状态，我们要实现这个功能其实很简单，只需在WorkflowProcessEditor类中覆盖父类的方法commandStackChanged，代码如下：
publicvoid commandStackChanged(EventObject event) {
firePropertyChange(IEditorPart.PROP_DIRTY);
super.commandStackChanged(event);
}
其实这个方法的原理很简单，当编辑器的命令堆栈发生改变时，修改编辑器状态为未保存。我们知道我们进行增加活动，删除活动等操作时，都是执行了一个个命令，而这些命令都保存在编辑器的命令堆栈里，所以我们每执行一个命令，编辑器的命令堆栈就发生改变。
再运行项目，我们就可以看到在编辑器处于已保存状态时，我们再进行操作，例如增加活动，删除活动，编辑器的状态就变成未保存了，至于在未保存状态，点保存按钮，还是未保存，这在以后，我们会解决。下一节，我们将介绍如何在活动之间增加和删除转移，如何在转移上增加拐点。