您可以执行以下操作以获取当前位置，然后检查它是否接近多段线。

MyLocationNewOverlay myLocation= new MyLocationNewOverlay(mapView) {
  @Override
  public void onLocationChanged(Location location, IMyLocationProvider source) {
    super.onLocationChanger(location, source);

    // Turn the current location into a GeoPoint
    GeoPoint currentPoint = new GeoPoint(location.getLatitude(), location.getLongitude);

    // Set tolerance for isCloseTo 
    // Might need to play around with this value 
    // and see which fits best for your needs
    double tolerance = 5.0;

    // Check if location is close to Polyline
    if (line.isCloseTo(currentPoint, tolerance, map)) {
        // Do here what you want to do, 
        // when location is close to Polyline
    }
  }
}

检查location/GeoPoint是否在给定的多边形内是一个比较复杂的工作，因为唯一的集成方法是基于MotionEvent而不是GeoPoint，并且只在非常特定的场景中返回正确的值，请参阅此作为参考。但也有一些答案，可能会对您的需要有用，例如this one。
参考文献：

• Get the current location
• OSMDroid Geopoint class
• Android位置类
• OSMDroid折线接近
• OSMDroid多边形.包含
• One way to check if point is in a polygon