import org.eclipse.core.commands.operations.IOperationApprover; //导入依赖的package包/类
private IStatus getRedoApproval(IUndoableOperation operation,
		IAdaptable info) {

	final Object[] approverArray = approvers.getListeners();

	for (int i = 0; i < approverArray.length; i++) {
		IOperationApprover approver = (IOperationApprover) approverArray[i];
		IStatus approval = approver.proceedRedoing(operation, this, info);
		if (!approval.isOK()) {
			if (DEBUG_OPERATION_HISTORY_APPROVAL) {
				Tracing.printTrace("OPERATIONHISTORY", //$NON-NLS-1$
						"Redo not approved by " + approver //$NON-NLS-1$
								+ "for operation " + operation //$NON-NLS-1$
								+ " approved by " + approval); //$NON-NLS-1$
			}
			return approval;
		}
	}
	return Status.OK_STATUS;
}
 

import org.eclipse.core.commands.operations.IOperationApprover; //导入依赖的package包/类
private IStatus getUndoApproval(IUndoableOperation operation,
		IAdaptable info) {

	final Object[] approverArray = approvers.getListeners();

	for (int i = 0; i < approverArray.length; i++) {
		IOperationApprover approver = (IOperationApprover) approverArray[i];
		IStatus approval = approver.proceedUndoing(operation, this, info);
		if (!approval.isOK()) {
			if (DEBUG_OPERATION_HISTORY_APPROVAL) {
				Tracing.printTrace("OPERATIONHISTORY", //$NON-NLS-1$
						"Undo not approved by " + approver //$NON-NLS-1$
								+ "for operation " + operation //$NON-NLS-1$
								+ " with status " + approval); //$NON-NLS-1$
			}
			return approval;
		}
	}
	return Status.OK_STATUS;
}
 

import org.eclipse.core.commands.operations.IOperationApprover; //导入依赖的package包/类
public static IOperationApprover getInstance() {
	if (instance == null) {
		synchronized (PlanReadOnlyOperationApprover.class) {
			if (instance == null) {
				try {
					instance = MissionExtender.construct(PlanReadOnlyOperationApprover.class);
				} catch (ConstructionException e) {
					instance = new PlanReadOnlyOperationApprover();
				}
			}
		}
	}
	return instance;
}
 

import org.eclipse.core.commands.operations.IOperationApprover; //导入依赖的package包/类
@Override
public void removeOperationApprover(IOperationApprover approver) {
	approvers.remove(approver);
}
 

import org.eclipse.core.commands.operations.IOperationApprover; //导入依赖的package包/类
@Override
protected IOperationApprover getUndoRedoOperationApprover(IUndoContext undoContext) {
	// since IResource is a more general way to compare java elements, we
	// use this as the preferred class for comparing objects.
	return new NonLocalUndoUserApprover(undoContext, this, new Object [] { getInputJavaElement() }, IResource.class);
}
 

import org.eclipse.core.commands.operations.IOperationApprover; //导入依赖的package包/类
/**
 * <p>
 * Add the specified approver to the list of operation approvers consulted
 * by the operation history before an undo or redo is allowed to proceed.
 * This method has no effect if the instance being added is already in the
 * list.
 * </p>
 * <p>
 * Operation approvers must be prepared to receive these the operation
 * approval messages from a background thread. Any UI access occurring
 * inside the implementation must be properly synchronized using the
 * techniques specified by the client's widget library.
 * </p>
 * 
 * @param approver
 *            the IOperationApprover to be added as an approver.
 * 
 */

@Override
public void addOperationApprover(IOperationApprover approver) {
	approvers.add(approver);
}