单元测试service注解注入，会空指针异常

import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.transaction.TransactionConfiguration;
import javax.annotation.Resource;
import junit.framework.TestCase;
import com.sinopec.carlife.model.Region;
import com.sinopec.carlife.service.api.RegionService;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations ={"classpath:spring/spring.xml"})
@Transactional
public class RegionServiceTest extends TestCase {
    @Resource(name="regionService")
    private RegionService regionService;
    @Test
    public void testFindRegions() {
        try {
            List<Region> regions = regionService.findRegions();
            System.out.println(regions.size());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}