1.at Delphi IDE, Add the "*.a" file Path to Library Path:

    a. Tools Menu

    b.Options 

    c.Delphi Options -> Library -> Selected platform "Android"

    d.Library path -> Add the path of *.a file

    e.OK

2.Here is an unit I made: utLibTest.pas is linked with libtest.a

unit utLibTest;{$link libtest.a}interfaceconst  libproj=‘libtest.a‘;(* procedure prototypes *)//将lon，2Pi周期内转换到-pi到pi之间function adjlon(lon:Double):double;cdecl;//将度分秒字符串转换成弧度，iss为字符串，rss为结束字符指针function dmstor(iss:PByte; var rss:PByte):double;cdecl;implementationfunction adjlon; external libproj;function dmstor; external libproj;end.

http://www.cnblogs.com/hezihang/p/5289644.html

Delphi XE10在 Android下调用静态库a文件