如何在Spring boot中从泛型参数（与任何类无关）中获取值

Question

我是某人的新人

我陷入了需要从amount变量中获取值的境地，而amount变量实际上不是任何类的一部分。如果你认为标题与主题不符，任何人都可以更改标题。我在下面提到的课程，你会发现我的努力是无用的，因为它似乎一团糟。如果有人能纠正或给我相同问题所在的参考堆栈，我将不胜感激。

一个ccount.java

    private Long id;
    private int accountNumber;
    private BigDecimal accountBalance;

AccountRepository

 public interface AccountDao extends CrudRepository<Account, Long> {
  Account findByAccountNumber(int accountNumber);
 }

会计服务

public interface AccountService {
void deposit(int accountNumber, String accountType, double amount);
} // these fields are not related to class field, I took this to send data to API

客户服务

public void deposit(String accountType, int accountNumber, double amount) {
    if (accountType.equalsIgnoreCase("Permanent")) {
        Account account = accountRepository.findByAccountNumber(accountNumber);
        account.setAccountBalance(account.getAccountBalance().add(new 
        BigDecimal(amount)));
        accountDao.save(account);

会计控制器

 @PostMapping("/deposit")
   public ResponseEntity<Object> depositPost(@RequestBody double amount, String accountType, 
   int accountNumber, Account account){
   accountService.deposit(accountType, accountNumber, 
   Double.parseDouble(String.valueOf(amount)));
   return ResponseEntity.ok("Record has been entered");

}

我收到的错误是：

  2021-10-21 20:19:58.660  WARN 22892 --- [nio-8088-exec-1] 
  .w.s.m.s.DefaultHandlerExceptionResolver : Resolved 
  [org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: 
  Cannot deserialize value of type `double` from Object value (token 
  `JsonToken.START_OBJECT`); nested exception is 
  com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of 
  type `double` from Object value (token `JsonToken.START_OBJECT`)
  at [Source: (PushbackInputStream); line: 1, column: 1]]

Answer 1

问题是你的帖子主体。我猜您将发送类似以下内容：

{
   "amount": 1000
}

这是一个JSON对象，无法反序列化为简单的双参数。您需要创建一个相应的类，如下所示：

public class AccountDto {
   private double amount;

   // constructor, getters, setters
}

现在，您需要在控制器中使用它：

@PostMapping("/deposit")
public ResponseEntity<Object> depositPost(@RequestBody AccountDto accountDto, String accountType, int accountNumber, Account account){
    accountService.deposit(accountType, accountNumber, accountDto.getAmount());
    return ResponseEntity.ok("Record has been entered");
}