在RCP中实现用托拽打开Editor

工作台窗口的Editor区域默认是显示的，而且它支持拖拽操作。在Eclipse里面，把一个文件拖到Editor区域，就会自动打开该文件的Editor。该特性是在 IWorkbenchWindowConfigurer 中设置。

在Password Gate中，当拖动Password Gate View中的一个Group 或者 Service到Editor区域，会在Editor显示该项的属性。

要实现此特性，有四部分是必须的。

1 实现必要的Transfer类型，而且定义Editor要支持哪些类型。在Password Gate中，Transfer是LocalSelectionTransfer。Transfer用来进行数据的序列化，它可以支持在同一个程序，或不同程序间拖拽。

2 因为在拖拽传递的过程中Editor Input 要实现序列化，所以要实现 IPersistableElement接口。

3 加入一个释放适配器，当一个元素被扔到Editor区域，它可以知道如何进行操作，其实就是打开该元素的Editor。

4 使Password View能够进行拖操作，它要提供供拖的元素。

下面进行代码实现。

在RCP的WorkbenchWindowAdvisor. preWindowOpen中定义要求Editor Area支持的拖入对象的类型，以及打开相应Editor的事件。

ApplicationWorkbenchWindowAdvisor.preWindowOpen()

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01publicvoidpreWindowOpen(){ 02 ...... 03configurer.addEditorAreaTransfer(LocalSelectionTransfer.getInstance()); 04configurer.configureEditorAreaDropListener(newEditorAreaDropAdapter( 05configurer.getWindow())); 06}

Row 03定义了Editor Area支持的Transfer为LocalSelectionTransfer, LocalSelectionTransfer为自己实现的传输介质类。Row 04定义了对拖入Editor Area的对象的处理方法。EditorAreaDropAdapter实现了DropTargetListener接口，用来监听Editor Area中的Drop事件，它会打开拖入Editor Area的对象所对应的Editor，如果同时拖入多个对象，它会打开每个对象对应的Editor.

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EditorAreaDropAdapter.java

01publicclassEditorAreaDropAdapterextendsDropTargetAdapter{ 02privateIWorkbenchWindowwindow; 03 04publicEditorAreaDropAdapter(IWorkbenchWindowwindow){ 05this.window=window; 06} 07 08publicvoiddragEnter(DropTargetEventevent){ 09//alwaysindicateacopy 10event.detail=DND.DROP_COPY; 11} 12 13publicvoiddragOperationChanged(DropTargetEventevent){ 14//alwaysindicateacopy 15event.detail=DND.DROP_COPY; 16} 17 18publicvoiddrop(finalDropTargetEventevent){ 19Displayd=window.getShell().getDisplay(); 20finalIWorkbenchPagepage=window.getActivePage(); 21if(page!=null){ 22d.asyncExec(newRunnable(){ 23publicvoidrun(){ 24asyncDrop(event,page); 25} 26}); 27} 28} 29 30privatevoidasyncDrop(DropTargetEventevent,IWorkbenchPagepage){ 31if(LocalSelectionTransfer.getInstance().isSupportedType( 32event.currentDataType)){ 33StructuredSelectionselection=(StructuredSelection)event.data; 34for(Iteratoriter=selection.iterator();iter.hasNext();){ 35Objecto=iter.next(); 36if(oinstanceofRecord){ 37IEditorInputinput=newRecordEditorInput((Record)o); 38try{ 39page.openEditor(input,RecordEditor.ID); 40}catch(Exceptione){ 41PwdgatePlugin.log("openediotrRecordEditor",e); 42} 43}elseif(oinstanceofGroup){ 44IEditorInputinput=newGroupEditorInput((Group)o); 45try{ 46page.openEditor(input,GroupEditor.ID); 47}catch(PartInitExceptione){ 48PwdgatePlugin.log("openediotrGroupEditor",e); 49} 50} 51} 52} 53} 54}

Row 18，用来处理Drop事件，Row 30的asyncDrop()方法用来打来相应对象的Editor.

现在Editor Area已经可以接收拖入对象了。下一步要使一个View支持拖出对象的功能。 下面的例子是在 Pass Gate View 中的 createPartControl() 方法中为一个 TreeViewer 添加拖出功能。

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PassGateView.java

01privatevoidinitDragAndDrop(){ 02Transfer[]transfer=newTransfer[]{LocalSelectionTransfer 03.getInstance()}; 04LocalSelectionDragAdapteradapter=newLocalSelectionDragAdapter( 05viewer); 06viewer.addDragSupport(DND.DROP_MOVE|DND.DROP_COPY,transfer,adapter); 07 08LocalSelectionDropAdapterdropAdapter=newLocalSelectionDropAdapter( 09viewer); 10viewer.addDropSupport(DND.DROP_MOVE|DND.DROP_COPY,transfer, 11dropAdapter); 12}

Row 06 为 TreeViewer 添加了监听拖动的事件，当在 TreeViewer 中有拖动时， LocalSelectionDragAdapter 把拖动的对象放入 LocalSelectionTransfer 中，通过其传到 Editor Area 中。

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LocalSelectionDragAdapter.java

01publicclassLocalSelectionDragAdapterextendsDragSourceAdapter{ 02 03ISelectionProviderselectionProvider; 04 05publicLocalSelectionDragAdapter(ISelectionProviderprovider){ 06selectionProvider=provider; 07} 08 09publicvoiddragFinished(DragSourceEventevent){ 10//TODOAuto-generatedmethodstub 11super.dragFinished(event); 12System.out 13.println("DragSourceListener.dragFinished(DragSourceEventevent)"); 14} 15 16publicvoiddragSetData(DragSourceEventevent){ 17System.out 18.println("DragSourceListener.dragSetData(DragSourceEventevent)"); 19DragSourcedragSource=(DragSource)event.widget; 20Controlcontrol=dragSource.getControl(); 21if(control!=control.getDisplay().getFocusControl()){ 22event.doit=false; 23return; 24} 25 26IStructuredSelectionselection=(IStructuredSelection)selectionProvider 27.getSelection(); 28 29if(selection.isEmpty()){ 30event.doit=false; 31return; 32} 33LocalSelectionTransfer.getInstance().setSelection(selection); 34event.doit=true; 35} 36 37publicvoiddragStart(DragSourceEventevent){ 38System.out 39.println("DragSourceListener.dragStart(DragSourceEventevent)"); 40} 41}

<!-- = END of automatically generated HTML code = --><!-- ======================================================== --> Row 33 ，将拖动的对象放入LocalSelectionTransfer中。Row 44 设置拖动有效，设为false的话，拖动无效。下面是LocalSelectionTransfer的实现。很容易理解。

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LocalSelectionTransfer.java

001publicclassLocalSelectionTransferextendsByteArrayTransfer{ 002 003privatestaticfinalStringTYPE_NAME="local-selection-transfer-format"+(newLong(System.currentTimeMillis())).toString();//$NON-NLS-1$; 004 005privatestaticfinalintTYPEID=registerType(TYPE_NAME); 006 007privatestaticfinalLocalSelectionTransferINSTANCE=newLocalSelectionTransfer(); 008 009privateISelectionselection; 010 011privatelongselectionSetTime; 012 013/** 014*Onlythesingletoninstanceofthisclassmaybeused. 015*/ 016privateLocalSelectionTransfer(){ 017} 018 019/** 020*Returnsthesingleton. 021* 022*@returnLocalSelectionTransfer 023*/ 024publicstaticLocalSelectionTransfergetInstance(){ 025returnINSTANCE; 026} 027 028/** 029*Returnsthelocaltransferdata. 030* 031*@returnthelocaltransferdata 032*/ 033publicISelectiongetSelection(){ 034returnselection; 035} 036 037/** 038*Testswhethernativedropdatamatchesthistransfertype. 039* 040*@paramresult 041*resultofconvertingthenativedropdatatoJava 042*@returntrueifthenativedropdatadoesnotmatchthistransfertype. 043*falseotherwise. 044*/ 045privatebooleanisInvalidNativeType(Objectresult){ 046return!(resultinstanceofbyte[]) 047||!TYPE_NAME.equals(newString((byte[])result)); 048} 049 050/** 051*Returnsthetypeidusedtoidentifythistransfer. 052* 053*@returnthetypeidusedtoidentifythistransfer. 054*/ 055protectedint[]getTypeIds(){ 056returnnewint[]{TYPEID}; 057} 058 059/** 060*Returnsthetypenameusedtoidentifythistransfer. 061* 062*@returnthetypenameusedtoidentifythistransfer. 063*/ 064protectedString[]getTypeNames(){ 065returnnewString[]{TYPE_NAME}; 066} 067 068/** 069*Overridesorg.eclipse.swt.dnd.ByteArrayTransfer#javaToNative(Object, 070*TransferData).Onlyencodethetransfertypenamesincetheselectionis 071*readandwritteninthesameprocess. 072* 073*@seeorg.eclipse.swt.dnd.ByteArrayTransfer#javaToNative(java.lang.Object, 074*org.eclipse.swt.dnd.TransferData) 075*/ 076publicvoidjavaToNative(Objectobject,TransferDatatransferData){ 077byte[]check=TYPE_NAME.getBytes(); 078super.javaToNative(check,transferData); 079} 080 081/** 082*Overrides 083*org.eclipse.swt.dnd.ByteArrayTransfer#nativeToJava(TransferData).Testif 084*thenativedropdatamatchesthistransfertype. 085* 086*@seeorg.eclipse.swt.dnd.ByteArrayTransfer#nativeToJava(TransferData) 087*/ 088publicObjectnativeToJava(TransferDatatransferData){ 089Objectresult=super.nativeToJava(transferData); 090if(isInvalidNativeType(result)){ 091PwdgatePlugin.log("invalidnattivetype",newException( 092"invalidnattivetype")); 093} 094returnselection; 095} 096 097/** 098*Setsthetransferdataforlocaluse. 099* 100*@params 101*thetransferdata 102*/ 103publicvoidsetSelection(ISelections){ 104selection=s; 105} 106 107/** 108*Returnsthetimewhentheselectionoperationthistransferisassociated 109*withwasstarted. 110* 111*@returnthetimewhentheselectionoperationhasstarted 112* 113*@seeorg.eclipse.swt.events.TypedEvent#time 114*/ 115publiclonggetSelectionSetTime(){ 116returnselectionSetTime; 117} 118 119/** 120*Setsthetimewhentheselectionoperationthistransferisassociated 121*withwasstarted.IfassigningthisfromanSWTevent,besuretouse 122*<code>setSelectionTime(event.time&0xFFFF)</code> 123* 124*@paramtime 125*thetimewhentheselectionoperationwasstarted 126* 127*@seeorg.eclipse.swt.events.TypedEvent#time 128*/ 129publicvoidsetSelectionSetTime(longtime){ 130selectionSetTime=time; 131} 132}

其实不光是拖到Area Editor，以上例子稍加改造，也可以实现拖到别的控件中，任何Control都可以添加托拽功能，例如可以从一个表格拖到另一个表格中，或拖到一个面板中。托拽功能让软件的可用性又提高了一个档次。