我想使用 jfree 圖表和來自 mysql 數(shù)據(jù)庫的數(shù)據(jù)創(chuàng)建一個餅圖，但我似乎遇到了錯誤。這是我的代碼。我有一個 LocationRepository 我在其中實現(xiàn)我的 sql 查詢   public interface LocationRepository extends JpaRepository<Location, Integer> {       //hibernate query language (jpql)       @Query("select type,count(type) from location group by type")       public List<Object[]> findTypeAndTypeCout();      }我也有我的 ReportUtility 接口，如下所示   public interface ReportUtil {      void generatePieChart(String path, List<Object[]> data);      }這是我的 ReportUtility 實現(xiàn)類  @Component  public class ReportUtilImpl implements ReportUtil {    @Override    public void generatePieChart(String path, List<Object[]> data) {    // TODO Auto-generated method stub    DefaultPieDataset dataset = new DefaultPieDataset();    for (Object[] objects : data) {        dataset.setValue(objects[0].toString(), new Double(objects[1].toString()));    }    JFreeChart chart = ChartFactory.createPieChart3D("Location Type Report", dataset);    try {        ChartUtilities.saveChartAsJPEG(new File(path+"/pieChart.jpeg"), chart, 300, 300);    } catch (IOException e) {        e.printStackTrace();    }  }}最后是控制器   @Controller    public class LocationController {  @Autowired  LocationService service;  @Autowired  LocationRepository repository;  @Autowired  ReportUtil reportUtil;  @Autowired  ServletContext sc;  @RequestMapping("/generateReport")   public String generateReport() {     String path = sc.getRealPath("/");     List<Object[]> data = repository.findTypeAndTypeCout();     reportUtil.generatePieChart(path, data);     return "report";        }     }