Posted on 2008-01-09 11:10
笑看人生 閱讀(1452)
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Java插件開發(fā)
哪個模型的控制器能接受在活動之間建立轉(zhuǎn)移的請求呢，只有活動模型的控制器了，因為活動模型中維護著活動的輸入和輸出轉(zhuǎn)移的列表，在活動控制器增加策略，使該控制器能接受建立轉(zhuǎn)移的請求，代碼如下：
protectedvoid createEditPolicies() 
{
//allow removal of the associated model element
installEditPolicy(EditPolicy.COMPONENT_ROLE, new AbstractActivityComponentEditPolicy
());
//allow the creation of transitions and
// and the reconnection of transitions between AbstractActivity instances
installEditPolicy(EditPolicy.GRAPHICAL_NODE_ROLE, new
TransitionGraphicalNodeEditPolicy());
}
這里安裝了TransitionGraphicalNodeEditPolicy策略，這個策略的代碼如下：
package com.example.workflow.policy;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.editpolicies.GraphicalNodeEditPolicy;
import org.eclipse.gef.requests.CreateConnectionRequest;
import org.eclipse.gef.requests.ReconnectRequest;
import com.example.workflow.commands.TransitionCreateCommand;
import com.example.workflow.model.AbstractActivity;
public class TransitionGraphicalNodeEditPolicy extends GraphicalNodeEditPolicy{
protected Command getConnectionCompleteCommand(CreateConnectionRequest request) {
TransitionCreateCommand cmd =
(TransitionCreateCommand)request.getStartCommand();
cmd.setTarget((AbstractActivity)getHost().getModel());
return cmd;
}
protected Command getConnectionCreateCommand(CreateConnectionRequest request) {
AbstractActivity source = (AbstractActivity)getHost().getModel();
TransitionCreateCommand cmd = new TransitionCreateCommand(source);
request.setStartCommand(cmd);
return cmd;
}
protected Command getReconnectSourceCommand(ReconnectRequest request) {
// TODO Auto-generated method stub
return null;
}
protected Command getReconnectTargetCommand(ReconnectRequest request) {
// TODO Auto-generated method stub
return null;
}
}這個類繼承了GraphicalNodeEditPolicy，并且覆蓋了getConnectionCreateCommand和getConnectionCompleteCommand，從這兩個方法的字面意思就明白它們在什么時候執(zhí)行，在getConnectionCreateCommand方法中，新建一個TransitionCreateCommand命令對象，并且把轉(zhuǎn)移的起始活動放入該命令對象中，在getConnectionCompleteCommand方法中，得到在getConnectionCreateCommand方法中創(chuàng)建的命令，并且把轉(zhuǎn)移的目標活動放入命令中。TransitionCreateCommand命令的代碼如下：
package com.example.workflow.commands;
import java.util.Iterator;
import org.eclipse.gef.commands.Command;
import com.example.workflow.model.AbstractActivity;
import com.example.workflow.model.Transition;
public class TransitionCreateCommand extends Command{
/** *//** The Transition instance. */
private Transition transition;
/** *//** Start endpoint for the Transition. */
private final AbstractActivity source;
/** *//** Target endpoint for the Transition. */
private AbstractActivity target;
public TransitionCreateCommand(AbstractActivity source){
if (source == null) {
throw new IllegalArgumentException();
}
setLabel("connection creation");
this.source = source;
}
public boolean canExecute() {
// disallow source -> source connections
if (source.equals(target)) {
return false;
}
// return false, if the source -> target connection exists already
for (Iterator iter = source.getSourceTransitions().iterator(); iter.hasNext
();) {
Transition tran = (Transition) iter.next();
if (tran.getTarget().equals(target)) {
return false;
}
}
return true;
}
public void execute() {
// create a new transition between source and target
transition = new Transition(source, target);
}
public void redo() {
transition.reconnect();
}
public void setTarget(AbstractActivity target) {
if (target == null) {
throw new IllegalArgumentException();
}
this.target = target;
}
public void undo() {
transition.disconnect();
}
}
在這個命令中，用剛才放入的兩個活動構(gòu)建一個轉(zhuǎn)移對象，其實通過代碼我們知道最終執(zhí)行的是在起始活動的輸入轉(zhuǎn)移列表中加入剛才新建的轉(zhuǎn)移對象，在目標活動的輸入轉(zhuǎn)移列表中加入新建的轉(zhuǎn)移對象。代碼如下：
void addTransition(Transition tran) {
if (tran == null || tran.getSource() == tran.getTarget()) {
thrownew IllegalArgumentException();
}
if (tran.getSource() == this) {
sourceTransitions.add(tran);
firePropertyChange(SOURCE_CONNECTIONS_PROP, null, tran);
} elseif (tran.getTarget() == this) {
targetTransitions.add(tran);
firePropertyChange(TARGET_CONNECTIONS_PROP, null, tran);
}
}
我們看到，向活動維護的轉(zhuǎn)移列表中加入轉(zhuǎn)移時，活動模型通知控制器它的SOURCE_CONNECTIONS_PROP和TARGET_CONNECTIONS_PROP屬性發(fā)生變化了，因此在活動控制器中應該根據(jù)這兩個屬性來屬性活動的視圖，代碼如下：
publicvoid propertyChange(PropertyChangeEvent evt) {
String prop = evt.getPropertyName();
if(AbstractActivity.SIZE_PROP.equals(prop)
||AbstractActivity.LOCATION_PROP.equals(prop)){
refreshVisuals();
}elseif(AbstractActivity.SOURCE_TRANSITIONS_PROP.equals(prop)){
refreshSourceConnections();
}elseif(AbstractActivity.TARGET_TRANSITIONS_PROP.equals(prop)){
refreshTargetConnections();
}
}
這里刷新的不是活動的視圖，而是活動的輸入和輸入轉(zhuǎn)移對應的視圖。只修改這些代碼，還不能在編輯器中展示出新建的轉(zhuǎn)移，還應該讓活動控制器實現(xiàn)NodeEditPart接口，同時要實現(xiàn)這接口中的四個方法，代碼如下：
private ConnectionAnchor anchor;
protected ConnectionAnchor getConnectionAnchor(){
if (anchor == null) {
anchor = new ChopboxAnchor(getFigure());;
}
returnanchor;
}
public ConnectionAnchor getSourceConnectionAnchor(ConnectionEditPart arg0) {
return getConnectionAnchor();
}
public ConnectionAnchor getSourceConnectionAnchor(Request arg0) {
return getConnectionAnchor();
}
public ConnectionAnchor getTargetConnectionAnchor(ConnectionEditPart arg0) {
return getConnectionAnchor();
}
public ConnectionAnchor getTargetConnectionAnchor(Request arg0) {
return getConnectionAnchor();
}
這四個方法就是實現(xiàn)轉(zhuǎn)移和活動連接的錨點。另外我們還要覆蓋父類中的兩個方法，得到活動模型維護的輸入轉(zhuǎn)移和輸出轉(zhuǎn)移，代碼如下：
protected List getModelSourceConnections() {
return getCastedModel().getSourceTransitions();
}
protected List getModelTargetConnections() {
return getCastedModel().getTargetTransitions();
}
這樣我們就可以在活動之間建立轉(zhuǎn)移了，效果下圖：
這樣我們就在兩個活動之間建立了轉(zhuǎn)移。那么如何刪除轉(zhuǎn)移呢，要刪除活動之間的轉(zhuǎn)移，應該在轉(zhuǎn)移控制器中安裝策略，代碼如下：
private Transition getCastedModel(){
return (Transition)getModel();
}
protectedvoid createEditPolicies() {
//Allows the removal of the transition model element
installEditPolicy(EditPolicy.CONNECTION_ROLE, new ConnectionEditPolicy() {
protected Command getDeleteCommand(GroupRequest request) {
returnnew TransitionDeleteCommand(getCastedModel());
}
});
}
這里安裝的是gef框架提供的策略，我們沒有創(chuàng)建自己的策略，而是直接覆蓋其中的getDeleteCommand，方法，在這個方法中新建了一個ransitionDeleteCommand命令，這個命令的代碼如下：
package com.example.workflow.commands;
import org.eclipse.gef.commands.Command;
import com.example.workflow.model.Transition;
public class TransitionDeleteCommand extends Command {
/** *//** Transition instance to disconnect. */
private final Transition transition;
public TransitionDeleteCommand(Transition tran) {
if (tran == null) {
throw new IllegalArgumentException();
}
setLabel("Transition deletion");
this.transition = tran;
}
public void execute() {
transition.disconnect();
}
public void undo() {
transition.reconnect();
}
}
這個類最終執(zhí)行的其實活動模型中的removeTransition方法，從活動模型維護的轉(zhuǎn)移列表中刪除它，而此時活動模型通知控制器自己的OURCE_CONNECTIONS_PROP和TARGET_CONNECTIONS_PROP屬性發(fā)生變化了，要刷新視圖，而這個我們在新建轉(zhuǎn)移時，已經(jīng)實現(xiàn)，因而這兒不用在實現(xiàn)了。這樣運行程序，我們就可以刪除活動之間的轉(zhuǎn)移了。
接下來我們再給轉(zhuǎn)移控制器安裝一個策略，目的是當選擇轉(zhuǎn)移，轉(zhuǎn)移有個反饋，給用戶感覺是已經(jīng)選擇了轉(zhuǎn)移，要不然，選擇和不選擇轉(zhuǎn)移，效果一樣，代碼如下：
protectedvoid createEditPolicies() {
//Selection handle edit policy.
// Makes the transition show a feedback, when selected by the user.
installEditPolicy(EditPolicy.CONNECTION_ENDPOINTS_ROLE,
new ConnectionEndpointEditPolicy());
//Allows the removal of the transition model element
installEditPolicy(EditPolicy.CONNECTION_ROLE, new ConnectionEditPolicy() {
protected Command getDeleteCommand(GroupRequest request) {
returnnew TransitionDeleteCommand(getCastedModel());
}
});
}
下一節(jié)我們介紹如何在轉(zhuǎn)移上新建，刪除和移動拐點。