findFutureList

findFutureList 允许在后台执行查询，我们可以等待查询并根据需要取消查询。

// find list using a background thread
FutureList<Order> futureList =
  Order.find.where()
    .status.equalTo(Order.Status.NEW)
    .findFutureList();

  // do something else ...

if (!futureList.isDone()){
  // you can cancel the query. If supported by the JDBC
  // driver and database this will actually cancel the
  // sql query execution on the database
  futureList.cancel(true);
}

// wait for the query to finish ... no timeout
List<Order> list = futureList.get();

// wait for the query to finish ... with a 30sec timeout
List<Order> list2 = futureList.get(30, TimeUnit.SECONDS);

findFutureCount

在后台线程中执行查找行计数查询。

这会返回一个 Future 对象，该对象可用于取消、检查执行状态（isDone 等）和获取值（带或不带超时）。

FutureRowCount<Customer> futureRowCount = DB.find(Customer.class)
.where().ilike("name", "Rob%")
.findFutureCount()

// do other things

拥有一个 Future 引用允许您检查执行是否完成，直接获取值（在等待值时阻塞）或在指定超时内获取值。

// Waits (blocks) for the calculation to be finished and returns the value
Integer count = futureRowCount.get();

// Waits for the calculation to be finished and returns the value
// if it happens under 10 seconds, otherwise throw an exception
Integer count = futureRowCount.get(10, TimeUnit.SECONDS);

if (futureRowCount.isDone()) {
  // Here we can fetch the value (assuming that everything went ok)
}

findFutureIds

类似于 findIds，您可以使用 findFutureIds 在后台线程中查找 Id 列表。

这会返回一个 Future 对象，该对象可用于取消、检查执行状态（isDone 等）和获取值（带或不带超时）。

FutureIds<Long> futureIds = futureList =
  Order.find.where()
    .status.equalTo(Order.Status.NEW)
    .findFutureIds();

要获取实际计算值

// Waits (blocks) for the calculation to be finished and returns the value
List<Long> ids = futureIds.get();

// Waits for the calculation to be finished and returns the value
// if it happens under 10 seconds, otherwise throw an exception
List<Long> ids = futureIds.get(10, TimeUnit.SECONDS);

if (futureIds.isDone()) {
  // Here we can fetch the value (assuming that everything went ok)
}