MySQLNULL,() : D :() NULL=,<>!= NULL"" NULL0=,<>!= NULL"""" () : A B D :() ,"" ,"" ,"" ,"" GFS,() : C :() GFSchunkserver GFS GFSmasterchunkserver main()() : B :() -1 0 1 2 chunkserver masterchunkserver () () rm=8,6,() : B :() 63 56 84 64 () : A B C D :() : C :() 1,4 3,4 2,3 1,2 3, 1,2,3,4,1,2,5,1,2,3,4,5.LRU,() : B :() 9 10 11 12 : A :() 5,1 : 1,2,3,4,1,2,5,1,2,3,4,5.1,2,3,4,1,2,5,1,2,3,4,5. ( ,, LRULRU 1,1 5,5 1,5 84567899235783670116,? : D :() AB EF 8B 9D : E :() 1,65535 65535,65535 65535,65536 65535,1 65536,65535 javaString str = "hello world" : A B C :() str+=' a' int strlen = str.length str=100 str=str+100。。。。。。以下内容略