原代碼：註入commonService對象失敗

　　@Autowired
    private static CommonService commonService;public static List<Map<String, Object>> getCode(String codeType,  boolean allOption ,String orderType){
        return commonUtil.commonService.getCode(codeType, allOption, orderType);
    }

commonService
 
在static狀態下不能夠被依賴註入,會拋出運行時異常java.lang.NullPointerException,為什麽呢?
靜態變量/類變量不是對象的屬性,而是一個類的屬性,spring則是基於對象層面上的依賴註入. 

解決方式1：

　　@Autowired
    private CommonService commonService;
    private static CommonUtil commonUtil;
    
    @PostConstruct
    public void init() {
        commonUtil = this;
        commonUtil.commonService 
 
= this.commonService;
    }
    
    public static List<Map<String, Object>> getCode(String codeType,  boolean allOption ,String orderType){
        return commonUtil.commonService.getCode(codeType, allOption, orderType);
    }

static類型autowired 註入失敗