如何在GAE上使用数据存储区游标与jpa

Question

任何机构都知道如何在JPA中使用Datastore游标？

Answer 1

你可以试试这个（改编自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...