典型重构3 (Try/Catch)

Try/Catch 块过多

public Customer GetCustomer(string customerId)
{
    try
    {
        var command = new SqlCommand();
        var reader = command.ExecuteReader();
        var customer = new Customer();
        while(reader)
        {
            customer.customerId=customerId;
            customer.CustomerName=reader["CustomerName"].ToString();
            customer.CustomerStatus=reader["CustomerStatus"].ToString();
            customer.LoyaltyProgram=reader["CustomerLoyaltyProgram"].ToString();
        }
        return customer;
    }
    catch(Exception ex)
    {
        _logger.LogException(ex);
        var customer=new Customer{CustomerStatus="nuknown"};
        return customer;
    }

将每个代码块中的这些方法析取到外部方法

private static Customer GetCustomerFromDataStore(string customerId)
{
    var command = new SqlCommand();
    var reader = command.ExecuteReader();
    var customer = new Customer();
    while(reader)
    {
        customer.customerId=customerId;
        customer.CustomerName=reader["CustomerName"].ToString();
        customer.CustomerStatus=reader["CustomerStatus"].ToString();
        customer.LoyaltyProgram=reader["CustomerLoyaltyProgram"].ToString();
    }
    return customer;
}

private Customer HandleDataStoreExceptionWhenRetrievingCustomer(Exception ex)
{
    _logger.LogException(ex);
    var customer=new Customer{CustomerStatus="nuknown"};
    return customer;
}

重构结果:

public Customer GetCustomer(string customerId)
{
    try
    {
        return GetCustomerFromDataStore(customerId);
    }
    catch(Exception ex)
    {
        return HandleDataStoreExceptionWhenRetrievingCustomer(ex);
    }
}