創建名為“viewResolver”的bean時出錯Spring

物體

@Entity
public class Card {
    @Id
    private Long id;

    private String full_name;
    private String login;
    private int balance;

    public Card() {
    }

    public Card(String full_name, String login, int balance) {
        this.full_name = full_name;
        this.login = login;
        this.balance = balance;
    }

    public Card(Long id, String full_name, String login, int balance) {
        this.id = id;
        this.full_name = full_name;
        this.login = login;
        this.balance = balance;
    }

    public String getFull_name() {
        return full_name;
    }

    public String getLogin() {
        return login;
    }

    public int getBalance() {
        return balance;
    }

    @Override
    public String toString() {
        .........    }
}

存盤庫

@Repository
public interface CardRepository extends JpaRepository<Card, Long>{
    @Query(value = "SELECT us.id, ...", nativeQuery = true)
    List<Card> findAll();
}

服務

public interface CardService {

    List<Card> findAll();
}

實施

@Service
public class CardServiceImpl implements CardService {

    @Autowired
    private CardRepository repository;

    @Override
    public List<Card> findAll() {
        List<ECard> list = new ArrayList<>();       
        return repository.findAll();
    }
}

控制器

@RestController
@RequestMapping("/card")
public class CardController {

    @Autowired
    private CardService cardService;

    public @ResponseBody List<Card> getAllCards() {
        return cardService.findAll();
    }

    @RequestMapping( value = "/card", method = RequestMethod.GET)
    public List<Card> cardList() {
        return cardService.findAll();
    }
}

我建立了這樣的服務。它作業得很好。但我想將它收到的資料保存到一個 xlsx 檔案中。該檔案應在應用程式啟動時保存。我想添加 Workbook 庫而不是現有的 Controller 類，或者更確切地說是它的內容。

類似的東西：

public class SaveCards {


    public static void saveCards() throws IOException {
        CardServiceImpl cardService = new CardServiceImpl();
        saveExcel(cardService.findAll(), "fileName.xlsx");
    }

    private static void saveExcel(List<Card> list, String fileName) throws IOException {

        Workbook workbook = new XSSFWorkbook();

        Sheet sheet = workbook.createSheet("Cards");
        sheet.setColumnWidth(0, 6000);
        sheet.setColumnWidth(1, 4000);

        Row header = sheet.createRow(0);

        CellStyle headerStyle = workbook.createCellStyle();
        headerStyle.setFillForegroundColor(IndexedColors.LIGHT_BLUE.getIndex());
        headerStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);

        XSSFFont font = ((XSSFWorkbook) workbook).createFont();
        font.setFontName("Arial");
        font.setFontHeightInPoints((short) 16);
        font.setBold(true);
        headerStyle.setFont(font);

        Cell headerCell = header.createCell(0);
        headerCell.setCellValue("full_name");
        headerCell.setCellStyle(headerStyle);

        headerCell = header.createCell(1);
        headerCell.setCellValue("login");
        headerCell.setCellStyle(headerStyle);

        headerCell = header.createCell(2);
        headerCell.setCellValue("balance");
        headerCell.setCellStyle(headerStyle);

        CellStyle style = workbook.createCellStyle();
        style.setWrapText(true);

        int ix_row=2;
        for (Card card : list) {
            Row row = sheet.createRow(ix_row);
            Cell cell = row.createCell(0);
            cell.setCellValue(eCard.getFull_name());
            cell.setCellStyle(style);

            cell = row.createCell(1);
            cell.setCellValue(eCard.getLogin());
            cell.setCellStyle(style);

            cell = row.createCell(2);
            cell.setCellValue(eCard.getBalance());
            cell.setCellStyle(style);

            ix_row  ;
        }

        FileOutputStream outputStream = new FileOutputStream(fileName);
        workbook.write(outputStream);
        workbook.close();
    }
}

但是，如果我將 Controller 類更改為 SaveCards 類，則會出現錯誤：Error created bean with name 'viewResolver' Spring

現在，結果如下：在 11.253 秒內啟動 DemonewApplication（JVM 運行時間為 11.882）。就是這樣，沒有任何動作發生，select 接收到的資料不會保存到 xlsx 檔案中。我究竟做錯了什么？

我知道必須在某個地方呼叫 SaveCards 類中的 saveCards 方法，但我不知道在哪里？

uj5u.com熱心網友回復：

您可以擴展org.springframework.boot.ApplicationRunner以在 Spring Boot 啟動時運行您的代碼。

@Component
class SaveCardsStartupRunner implements ApplicationRunner 
{
    @Autowired
    private SaveCards saveCards;

    @Override
    public void run(ApplicationArguments args)
    {
        saveCards.saveCards();
    }
}

并且SaveCards類必須更改如下：

@Component
public class SaveCards {
{
    @Autowired
    private CardService cardService;
    
    public void saveCards() throws IOException {
        saveExcel(cardService.findAll(), "fileName.xlsx");
    }

    private void saveExcel(List<Card> list, String fileName) throws IOException {...}
}

標籤：爪哇 春天

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