如何在GAE上使用jpa上的数据存储区游标 [英] How to use datastore cursors with jpa on GAE

问题描述

任何机构都知道如何在JPA中使用Datastore Cursors？

Any body know how to use Datastore Cursors with JPA?

推荐答案

=http://code.google.com/appengine/docs/java/datastore/queriesandindexes.html#Query_Cursors =nofollow noreferrer> JDO示例）：

Can you try this (adapted from the JDO sample):

List<Employee> results = (List<Employee>) query.execute();
// Use the first 20 results...

Cursor cursor = JPACursorHelper.getCursor(results);
String cursorString = cursor.toWebSafeString();
// Store the cursorString...

// ...

// Query query = the same query that produced the cursor
// String cursorString = the string from storage
Cursor cursor = Cursor.fromWebSafeString(cursorString);
query.setHint(JPACursorHelper.CURSOR_HINT, cursor);
query.setFirstResult(0);
query.setMaxResults(20);

List<Employee> results = (List<Employee>) query.execute();
// Use the next 20 results...

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