无法自动装配一个bean

Question

我有一个要自动装配的存储库的 DaoImpl。 class是这样的

@Repository("referralDao")
@Transactional(value = "txManager", propagation = Propagation.REQUIRES_NEW , readOnly = true)
public class ReferralDaoImpl extends ReferralCommonDao  implements IReferralDao {
    @Override
    public ReferralProperty getReferralProperty(String name) {
        String sQuery = " FROM " + ReferralProperty.class.getSimpleName() + " WHERE name = :name";
        Query query = getCurrentSession().createQuery(sQuery);
        query.setParameter("name", name);
        ReferralProperty property = (ReferralProperty)query.uniqueResult();
        return property;
    }
}

我还有一个控制器，我在其中自动装配这个 class。控制器：

@Controller
@RequestMapping(value="UploadExcel")
public class ExcelController {
       private boolean isMultipart;
   private String filePath;
   private String fileName;
   private int maxFileSize = 50 * 1024;
   private int maxMemSize = 4 * 1024;
   private File file ;
  @Autowired
  private ReferralDaoImpl referralDaoImpl;

  private ReferralProperty referralProperty;

@RequestMapping(value="/excel", method=RequestMethod.GET )
public String excel() {
    return "UploadExcel/excel";
}
@RequestMapping(value="UploadNew" , method=RequestMethod.POST)
public String excel1() {
    return "UploadExcel/excel";
}
@RequestMapping(value = "Upload", method = RequestMethod.POST)
public String doPost (HttpServletRequest request, HttpServletResponse response)  
        throws ServletException, IOException , Exception{  
          isMultipart = ServletFileUpload.isMultipartContent(request);
          response.setContentType("text/html");
          referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.directory");
          filePath = referralProperty.getValue();
      //    java.io.PrintWriter out = response.getWriter( );
          if( !isMultipart ){
             return "index";
          }
          DiskFileItemFactory factory = new DiskFileItemFactory();     
          factory.setSizeThreshold(maxMemSize);     
          factory.setRepository(new File("/home/aman"));
          ServletFileUpload upload = new ServletFileUpload(factory);         
          upload.setSizeMax( maxFileSize );
          try{ 
          List fileItems = upload.parseRequest(request);
          Iterator i = fileItems.iterator();           
          while ( i.hasNext () ) 
          {
             FileItem fi = (FileItem)i.next();
             if ( !fi.isFormField () )  
             {

                String name = fi.getName();
                System.out.println(name +  "\n\n\n\n\n\n\n");
                referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.name");
                /*referralProperty.setValue(name);
                referralProperty.setDescription(name);
                referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.name");
                System.out.println(referralProperty.getDescription() +  "\n\n\n\n\n\n\n");*/
                fileName = referralProperty.getValue();
                if( fileName.lastIndexOf("\") >= 0 ){
                   file = new File( filePath + 
                   fileName.substring( fileName.lastIndexOf("\"))) ;
                }else{
                   file = new File( filePath + 
                   fileName.substring(fileName.lastIndexOf("\")+1)) ;
                }
                fi.write( file ); 
                processExcel p = new processExcel();
                int p1 = p.Excel();
           //     Excel();
             }
          }    
       }catch(Exception ex) {
           System.out.println(ex);
       }
          return "UploadExcel/downloadexcel";
      }  
@RequestMapping(value = "Download", method = RequestMethod.POST)
public void doPost1(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    PrintWriter out = response.getWriter();
    referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.directory");
    String filepath = referralProperty.getValue();
    referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.name");
    String filename = referralProperty.getValue();
    response.setContentType("APPLICATION/OCTET-STREAM");
    response.setHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");
    FileInputStream fileInputStream = new FileInputStream(filepath + filename);
    int i;
    while ((i = fileInputStream.read()) != -1) {
        out.write(i);
    }
    fileInputStream.close();
    out.close();
}
public int Excel() throws Exception
{
    System.out.println(referralDaoImpl.toString());
    System.out.println(referralProperty.toString());
    try {
        boolean eligible;
        referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.directory");
        String filepath = referralProperty.getValue();
        referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.name");
        String filename = referralProperty.getValue();
        FileInputStream myInput = new FileInputStream(filepath+filename);
         XSSFWorkbook myWorkBook = new XSSFWorkbook(myInput);
         XSSFSheet mySheet = myWorkBook.getSheetAt(0);
         XSSFRow row = mySheet.getRow(0);
         int emailColumn = 0;
         int eligibilityColumn = row.getLastCellNum();
         for(Cell cell : row) {
             XSSFCell cell1 = (XSSFCell)cell;
             if(cell1.getStringCellValue().equals("email") || cell1.getStringCellValue().equals("Email")) 
             {
                 emailColumn = cell1.getColumnIndex();
                 break;
             }

         }
         XSSFCell cell2 = (XSSFCell)row.createCell(eligibilityColumn);
         cell2.setCellValue("Eligibility");
         for (Row row1 : mySheet)
         {       
             XSSFCell cell1 = (XSSFCell)row1.getCell(emailColumn);
             if(row1.getRowNum()!=0 && cell1!=null) {
             eligible = isValidRefree(cell1.getStringCellValue());
             if(eligible==true)
             {
                 cell2 = (XSSFCell)row1.createCell(eligibilityColumn);
                 cell2.setCellValue("Eligible");
             }
             else
             {
                 cell2 = (XSSFCell)row1.createCell(eligibilityColumn);
                 cell2.setCellValue("InEligible");           
             } 
         }
         }
         myInput.close();
         FileOutputStream output_file =new FileOutputStream(new File(filepath+filename));     
         System.out.println(filepath+filename);
         myWorkBook.write(output_file);       
         output_file.close();     

    } catch (Exception e) {
        System.out.println(e.toString());
    }   
    return 1;
}

public boolean isValidRefree( String email)
{
    return true;
}

}

这里 class 没有任何问题地自动装配，一切正常。现在，如果我制作另一个包和一个名为 processExcel.java 的 class，class 看起来像这样：

@Service
public class processExcel {

@Autowired
private ReferralDaoImpl referralDaoImpl;

private ReferralProperty referralProperty;

public int Excel() throws Exception
{

    //System.out.println(referralDaoImpl.toString());
    System.out.println(referralProperty.toString());
    try {
        boolean eligible;
        System.out.println("akjsfbjaksf" + "\n\n\n\n\n");
        referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.directory");
        System.out.println("akjsfbjaksf" + "\n\n\n\n\n");
        String filepath = referralProperty.getValue();
        System.out.println("akjsfbjaksf" + "\n\n\n\n\n");
        referralProperty = referralDaoImpl.getReferralProperty("excel.sheet.name");
        String filename = referralProperty.getValue();
        System.out.println("akjsfbjaksf" + "\n\n\n\n\n");
        FileInputStream myInput = new FileInputStream(filepath+filename);
         XSSFWorkbook myWorkBook = new XSSFWorkbook(myInput);
         XSSFSheet mySheet = myWorkBook.getSheetAt(0);
         Iterator<Row> rowIter = mySheet.rowIterator();
         while(rowIter.hasNext()){
             System.out.println("akjsfbjaksf" + "\n\n\n\n\n");
             XSSFRow myRow = (XSSFRow) rowIter.next();
             Iterator<Cell> cellIter = myRow.cellIterator();
             if(cellIter.hasNext()) {
                 XSSFCell cell = (XSSFCell)cellIter.next();
                 String email = cell.getStringCellValue();
                 eligible = isValidRefree (email);
                 if(eligible == true)
                 {
                     if (cellIter.hasNext()){    
                         XSSFCell cell1 = (XSSFCell) cellIter.next();
                         cell1.setCellValue("Eligible");
                     }
                     else
                     {
                         XSSFCell cell1 = myRow.createCell(1);
                         cell1.setCellValue("Eligible");
                     }

                 }
                 else
                 {
                     if(cellIter.hasNext()){
                         XSSFCell cell1 = (XSSFCell) cellIter.next();
                         cell1.setCellValue("InEligible");
                     }
                     else
                     {
                         XSSFCell cell1 = myRow.getCell(1);
                         cell1.setCellValue("InEligible");
                     }

                 }                       
             }   
         }
         myInput.close();
         FileOutputStream output_file =new FileOutputStream(new File(filepath+"ama.xlsx"));     
         System.out.println(filepath+filename);
         myWorkBook.write(output_file);       
         output_file.close();    

    } catch (Exception e) {
        System.out.println(e.toString());
    }

    return 1;
}

public boolean isValidRefree( String email)
{
        return true;
    }
}

并尝试自动装配 ReferralDaoImpl 它不起作用并显示 NUllPointerException。为什么会这样？

Answer 1

确保 spring 上下文在 class 加载之前已初始化并加载。

Answer 2

检查您的代码，我发现您在 ExcelController 此处 processExcel p = new processExcel(); 中手动实例化了您的 processExcel，这就是您的问题。

为了让 Spring 能够自动装配任何你需要使用 Spring 创建的 bean，当你使用 new 这样做时，Spring 不会'对此对象一无所知。

正确的使用方法是自动装配 class，并使用这个 bean 而不是创建你自己的：

@Autowired
private processExcel processExcel;

请注意，不要对 classes 名称使用小写字母，并且始终自动装配接口，而不是实现。

无法自动装配一个bean

Not being able to autowire a bean

java

spring

spring-mvc

autowired