mv: move from util package to app packge

Signed-off-by: 410063005@163.com <410063005@163.com>
add: ant build file

Signed-off-by: 410063005@163.com <410063005@163.com>
add: Conditions
add: nullOrEmpty(String str)
add: unit test

Signed-off-by: 410063005@163.com <410063005@163.com>