java - Which return type use in spring mvc in @RequestMapping method? -

i know in spring mvc in @controller class in @requestmapping method can return

1. string
2. model
3. modelandview

i don't understand differencies between these actions. can explain me it?

in spring 3.2.x there more 3. see docs @ spring website. latests spring (4.2.x) documentation.

the following supported return types:

• a modelandview object, model implicitly enriched command objects , results of @modelattribute annotated reference data accessor methods.
• a model object, view name implicitly determined through requesttoviewnametranslator , model implicitly enriched command objects , results of @modelattribute annotated reference data accessor methods.
• a map object exposing model, view name implicitly determined through requesttoviewnametranslator , model implicitly enriched command objects , results of @modelattribute annotated reference data accessor methods.
• a view object, model implicitly determined through command objects , @modelattribute annotated reference data accessor methods. handler method may programmatically enrich model declaring model argument (see above).
• a string value interpreted logical view name, model implicitly determined through command objects , @modelattribute annotated reference data accessor methods. handler method may programmatically enrich model declaring model argument (see above).
• void if method handles response (by writing response content directly, declaring argument of type servletresponse / httpservletresponse purpose) or if view name supposed implicitly determined through requesttoviewnametranslator (not declaring response argument in handler method signature).
• if method annotated @responsebody, return type written response http body. return value converted declared method argument type using httpmessageconverters. see section called “mapping response body @responsebody annotation”.
• a httpentity** or **responseentity object provide access servlet response http headers , contents. entity body converted response stream using httpmessageconverters. see section called “using httpentity”.
• a callable can returned when application wants produce return value asynchronously in thread managed spring mvc.
• a deferredresult can returned when application wants produce return value thread of own choosing.
• any other return type considered single model attribute exposed view, using attribute name specified through @modelattribute @ method level (or default attribute name based on return type class name). model implicitly enriched command objects , results of @modelattribute annotated reference data accessor methods.