Hi Radhesh,
according to your routing configuration your are passed the parameter "Entity" for your details view.
In your detail view controller's onRouteMatched method you take this parameter and set the view's binding context accordingly. Either you pass a simple value and build the URL for the OData GetEntity yourself [e.g. YourEntitySet(KeyField1='keyvalue1',KeyField2='keyvalue2') ] or your pass the binding path with this parameter.
Please refer to this documentation (the "Controller" section) to have a best practive approach.
Step 9: Detail View - UI Development Toolkit for HTML5 (SAPUI5) - SAP Library
If you set a binding context using the YourEntitySet( [specify all key fields with values here] ) notation the the GetEntity Method will be called in NW Gateway.