Question

这里我提供了抛出异常的hibernate项目代码

例外：

org.hibernate.StaleObjectStateException:Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect):

当我们调用下面提到的方法时我想让这个线程安全

public String saveAnswer(String assignmentid, String answerid, String answer) throws Exception {

        getStudentManager().logRequestedAnswer(answerid, answer);

        User user = getUserManager().getCurrentUser();

        HttpSession session = WebContextFactory.get().getSession();
        int practiceElapsedTime = getStudentManager().touchPracticeTime(assignmentid, session);
        long practiceUpdateTime = ((Date) session.getAttribute("student_current_practice_last_update")).getTime();

        StudentAnswer savedAnswer = getStudentManager().saveAnswer(user, assignmentid, answerid, answer);

        Map<String, Object> result = new HashMap<String, Object>();
        result.put("answerid", savedAnswer.getAnswerKey().getObjectid());
        result.put("answer", savedAnswer.getAnswer());

        //we're synching the client's time with the server on saves
        result.put("practiceElapsedTime", practiceElapsedTime);
        result.put("practiceUpdateTime", practiceUpdateTime);

        if (savedAnswer.getAssignmentStatus().isCompleted())
            result.put("progress", savedAnswer.getAssignmentStatus().getPercent());
        else
            result.put("progress", savedAnswer.getAssignmentStatus().getProgress());

        StringWriter json = new StringWriter();
        ObjectMapper mapper = new ObjectMapper();
        mapper.writeValue(json, result);
        return json.toString();

    }

Answer 1

我用hibernate学到了两件事。首先，如果快速多次保存同一个对象，则可能会出现StaleObjectStateException。这是由于桌面上的版本控制。一个简单的解决方案是禁用它。如果您的表由多个线程访问，您应该考虑锁定：http://docs.jboss.org/hibernate/orm/4.0/devguide/en-US/html/ch05.html

Answer 2

这可能意味着在您的事务提交之前，您尝试更新的行已经被其他一些线程更新过。检查多个线程是否同时处理相同的记录。

当我们保存答案时，hibernate异常行被更新或删除了异常

2 个答案: