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? Using Cache#readEntriesServer and Cache#addEntry (after you save entries from GET request).
Just let me ask you why do you need such action?
Regards,
Jan Gold