Hi Serkan,
you are probably using old SKD libraries with Cache which is described here: http://help.sap.com/saphelp_smp304sdk/helpdata/en/7c/0b0f9070061014a7b1c78f0f331130/content.htm
There is no method in SDK libraries, that will help you with such action. If you really need to save all entries from your server cache to your local cache, you will need to do it by your self. How? After you save entries from GET request use Cache#readEntriesServer (reed all entries from server cache) and then Cache#addEntry (store the entries into local cache).
Just let me ask you why do you need this?
Regards,
Jan Gold