已知函数\(f(x)=\ln x\)，\(x _{1}\)，\(x _{2} ∈(0 , \dfrac {1}{e} )\)，且\(x _{1} < x _{2}\)，则下列结论中正确的是\((\:\:\:\:)\)
A. \((x _{1} -x _{2} )[f(x _{1} )-f(x _{2} )] < 0\)
B. \(f( \dfrac {x_{1}+x_{2}}{2} ) < f( \dfrac {f(x_{1})+f(x_{2})}{2} )\) C. \(x _{1} f(x _{2} ) > x _{2} f(x _{1} )\) D. \(x _{2} f(x _{2} ) > x _{1} f(x _{1} )\)
