EMF学习--CompoundCommand
1、新建插件工程graph，建立ecore文件。
2、由ecore生成对应的genmodel文件，用来生成Model代码，edit和editor两个插件。
3、修改edit插件的EdgeItemProvider类，使Edge的source属性可以和Node的outgoing属性之间实现双向引用。
覆写createSetCommand方法，当feature为GraphPackage.Literals.EDGE__SOURCE时，触发SetSrcEdgeCompoundCommand这样一个组合命令。
@Overrideprotected Command createSetCommand(EditingDomain domain, EObject owner, EStructuralFeature feature, Object value) {if (feature == GraphPackage.Literals.EDGE__SOURCE) {return new SetSrcEdgeCompoundCommand(domain, owner, feature, value);}return super.createSetCommand(domain, owner, feature, value);}private class SetSrcEdgeCompoundCommand extends CompoundCommand {private EditingDomain domain;private EObject owner;private Object value;public SetSrcEdgeCompoundCommand(EditingDomain domain, EObject owner, EStructuralFeature feature, Object value) {this.domain = domain;this.owner = owner;this.value = value;append(new SetCommand(domain, owner, feature, value));}@Overridepublic void execute() {Node node = (Node) value;if (node != null) {Edge outgoingEdge = node.getOutgoing();if (outgoingEdge != null) {// 关联一个存在其他关联的对象appendAndExecute(new SetCommand(domain, node, GraphPackage.Literals.NODE__OUTGOING, null));appendAndExecute(new SetCommand(domain, outgoingEdge, GraphPackage.Literals.EDGE__SOURCE, null));}}Edge edge = (Edge) owner;Node sourceNode = edge.getSource();if (sourceNode == null) {// addappendAndExecute(new SetCommand(domain, node, GraphPackage.Literals.NODE__OUTGOING, edge));} else if (node == null) { // removeappendAndExecute(new SetCommand(domain, sourceNode, GraphPackage.Literals.NODE__OUTGOING, null));} else { // editappendAndExecute(new SetCommand(domain, sourceNode, GraphPackage.Literals.NODE__OUTGOING, null));appendAndExecute(new SetCommand(domain, node, GraphPackage.Literals.NODE__OUTGOING, edge));}super.execute();}}