确定地理点是否在州边界的X米范围内（使用shapefile作为边界数据）

So I'm writing a Java app, and I've got an ESRI Shapefile which contains the borders of all the U.S. states. What I need is to be able to determine whether any given lat/lon point is within a specified distance from ANY state border line - i.e., I will So I'm writing a Java app, and I've got an ESRI