java - ATG:更新订单模式

Question

众所周知，您必须使用以下模式才能更新 ATG Form-Handlers 中不继承自 PurchaseProcessFormHanlder 的订单:

boolean acquireLock = false;
ClientLockManager lockManager = getLocalLockManager();

try {
    acquireLock = !lockManager.hasWriteLock(profile.getRepositoryId(), Thread.currentThread());
    if (acquireLock) {
        lockManager.acquireWriteLock(profile.getRepositoryId(), Thread.currentThread());
    }

    boolean shouldRollback = false;

    TransactionDemarcation transactionDemarcation = new TransactionDemarcation();
    TransactionManager transactionManager = getTransactionManager();

    transactionDemarcation.begin(transactionManager, TransactionDemarcation.REQUIRED);

    try {
        synchronized (getOrder()) {
            ...
            ...
            ...
        }
    } catch (final Exception ex) {
        shouldRollback = true;
        vlogError(ce, "There has been an exception during processing of order: {0}", getOrder().getId());
    } finally { 
        try {
            transactionDemarcation.end(shouldRollback);
        } catch (final TransactionDemarcationException tde) {
            vlogError(tde, "TransactionDemarcationException during finally: {0}", tde.getMessage());
        } finally {
            vlogDebug("Ending Transaction for orderId: {0}", order.getId());
        }
    }
} catch (final DeadlockException de) {
    vlogError(de, "There has been an exception during processing of order: {0}", order.getId());
} catch (final TransactionDemarcationException tde) {
    vlogError(tde, "There has been an exception during processing of order: {0}", order.getId());
} finally {
    try {
        if (acquireLock) {
            lockManager.releaseWriteLock(getOrder().getProfileId(), Thread.currentThread(), true);
        }
    } catch (final Throwable th) {
        vlogError(th, "There has been an error during release of write lock: {0}", th.getMessage());
    }
}

理论上，任何继承自 PurchaseProcessFormHandler 的 FormHandler 都已实现以下步骤 OOTB:

1. 获取LocalLockManager以避免并发线程修改相同的顺序:

   try {
       acquireLock = !lockManager.hasWriteLock(profile.getRepositoryId(), Thread.currentThread());
       if (acquireLock) {
           lockManager.acquireWriteLock(profile.getRepositoryId(), Thread.currentThread());
       }
   } catch (final DeadlockException de) {
       vlogError(de, "There has been an exception during processing of order: {0}", order.getId());
   }
   

2. 创建新的交易:

   try {
       TransactionDemarcation transactionDemarcation = new TransactionDemarcation();
       TransactionManager transactionManager = getTransactionManager();
   
       transactionDemarcation.begin(transactionManager, TransactionDemarcation.REQUIRED);
   } catch (final TransactionDemarcationException tde) {
       vlogError(tde, "There has been an exception during processing of order: {0}", order.getId());
   }
   

3. 结束正在使用的事务:

   try {
       TransactionManager transactionManager = getTransactionManager();
       Transaction transaction = transactionManager.getTransaction();
   
       // If transaction is elegible for commiting: 
       transactionManager.commit();
       transaction.commit();
   
       // otherwise
       transactionManager.rollback();
       transaction.rollback();
   } catch (final Exception ex) {
       error = true;
       vlogError(ex, "There has been an exception during processing of order: {0}", order.getId());
   } finally {
       // handle the error
   }
   

4. 释放用于事务的锁:

   finally {
       ClientLockManager lockManager = getLocalLockManager();
       lockManager.releaseWriteLock(profile.getRepositoryId(), Thread.currentThread(), true);
   }
   

根据 ATG 文档，以下方法实现上述行为:

1. 方法:beforeSet

   Called before any setX methods on this form are set when a form that modifies properties of this form handler is submitted. Creates a transaction if necessary at the beginning of the form submission process, optionally obtaining a local lock to prevent multiple forms from creating transactions that may modify the same order.

   • 步骤:1 和 2

2. 方法:afterSet

   Called after any setX methods on this form are set when a form that modifies properties of this form handler is submitted. Commits or rolls back any transaction created in beforeSet, and releases any lock that was acquired at the time.

   • 步骤:3 和 4

例如您只需办理以下手续即可更新订单:

1. 同步将用于订单更新的代码块，以避免线程并发。

   synchronized (getOrder()) {
       ...
       ...
       ...
   }
   

2. 执行订单修改:

   synchronized (getOrder()) {
       getOrder().setXXX();
       getOrder().removeXXX();
   }
   

3. 更新订单(将调用updateOrder管道链):

   synchronized (getOrder()) {
       ...
       ...
       ...
       getOrderManager().updateOrder(order);
   }
   

这非常简单，除非您必须在以下任何情况下编辑订单:

• 不在 PurchaseProcessFormHandler 层次结构中的表单处理程序或自定义表单处理程序。
• 帮助程序或工具类。
• 处理器
• ATG REST 网络服务
• &c

如果是这样，您将必须在组件中实现事务模式。

问题!

• 除了事务模式之外，还有其他已知的模式可以使用吗？
• 是否可以像 ATG 在 PurchaseProcessFormHandler 中那样实现/覆盖 FormHandler 中的 beforeSet 和 afterSet 方法
• 您还知道其他方法吗？

Answer 1

您上面概述的一系列步骤是更新订单的规定步骤系列。

请随意以任何您认为有用的方式将其分解出来。只需确保当您更新订单时，您或您继承的代码已执行必要的步骤。

ATG 进行类似因式分解的一种常见方法是，对于给定方法，例如 X(...)，您将拥有 preX(...)、doX(...) 和 postX(...) 方法。您可以使用 preX() 和 postX() 方法中的所有样板代码创建一个抽象类，甚至可以声明为最终类，并将 doX() 声明为抽象类。然后，您的组件将从抽象类继承，并且必须实现 doX() 方法。您可能还需要显式处理异常。

本质上，这就是标准表单处理程序所做的事情(以不同的名称)。

例如；

public final void X(...) {
  preX(...); // call the pre method

  try {
    doX(...); // call the do method
  } catch (XException xe) {
    // handle error
  }

  postX(...); // call the post method
}

protected final void preX(...) {
  // do everything you need to do before your customer code
}

protected final void postX(...) {
  // do everything you need to do after your customer code
}

protected abstract void doX(...) throws XException;

您可以做的另一件事是定义一个包含所有样板代码的注释，而不是从抽象类继承。

您可以用类似的方式做的第三件事，但很难硬塞进 ATG 代码中，可能是使用第三方框架定义一个方面或方法调用拦截器。

但是，再次强调，无论您做什么、如何做，只要确保遵循所有步骤即可。