To create an MBean, we can use @Managed annotations to convert any class into an MBean. The class BankTransferService transfers an amount from one account to another. We will use this example for further understanding:

@Component
@ManagedResource(objectName = "com.packt.springhighperformance.ch4.mbeans : name=BankMoneyTransferService", description = "Transfers money from one account to another")
public class BankMoneyTransferService {

  private Map<String, Integer> accountMap = new HashMap<String, 
  Integer>();
   {
    accountMap.put("12345", 20000);
    accountMap.put("54321", 10000);
   };

  @ManagedOperation(description = "Amount transfer")
  @ManagedOperationParameters({
      @ManagedOperationParameter(name = "sourceAccount", description = 
       "Transfer from account"),
      @ManagedOperationParameter(name = "destinationAccount",         
        description = "Transfer to account"),
      @ManagedOperationParameter(name = "transferAmount", 
      description = 
        "Amount to be transfer") })
  public void transfer(String sourceAccount, String     
  destinationAccount, int transferAmount) {
    if (transferAmount == 0) {
      throw new IllegalArgumentException("Invalid amount");
    }
    int sourceAcctBalance = accountMap.get(sourceAccount);
    int destinationAcctBalance = accountMap.get(destinationAccount);

    if ((sourceAcctBalance - transferAmount) < 0) {
      throw new IllegalArgumentException("Not enough balance.");
    }
    sourceAcctBalance = sourceAcctBalance - transferAmount;
    destinationAcctBalance = destinationAcctBalance + transferAmount;

    accountMap.put(sourceAccount, sourceAcctBalance);
    accountMap.put(destinationAccount, destinationAcctBalance);
  }

  @ManagedOperation(description = "Check Balance")
  public int checkBalance(String accountNumber) {
    if (StringUtils.isEmpty(accountNumber)) {
      throw new IllegalArgumentException("Enter account no.");
    }
    if (!accountMap.containsKey(accountNumber)) {
      throw new IllegalArgumentException("Account not found.");
    }
    return accountMap.get(accountNumber);
  }

}

In the preceding class, the @ManagedResource annotation will mark the class as MBean, and the @ManagedAttribute and @ManagedOperation annotations can be used to expose any attributes or methods. The @Component annotation will make sure that all classes annotated with @Component, @Service, or @Repository will be added to the Spring context.