公开分布式高性能查询的源代码和部署方案(三）

7）Versant数据库的对象查询 Versant数据库能够支持SQL查询和NOSQL查询两种模式，如下为在查到第一个目标对象，以后采用NOSQL方式，自动执行朋友圈子遍历的例子： VQLQuery q = new VQLQuery( session, DistributedDatabaseManager.getInstance().HPC_DEMO_NETWORK_NAME, "select selfoid from com.versant.domain.Person where firstName='AAF1' and lastName='AAL1'"); //"select * from com.versant.domain.Person"); System.out.println("About to execute query, and load root object."); VEnumeration results = q.execute(); // 建立已经走过的朋友路径，避免回环 System.out .println("--------------------------------------------------------------------------"); long middleTime = System.currentTimeMillis(); HashSet<Person> friendSet = new HashSet<Person>(); if (results.hasMoreElements()) { Person person = (Person) results.nextElement(); friendSet.add(person); System.out.println("Start Person found:" + person.getFirstName() + "/" + person.getLastName() + ", about to print friend path."); Iterator ite = person.getFriends().iterator(); System.out.print("<<<  -> " + person.getFirstName() + "/" + person.getLastName()); while (ite.hasNext()) { Person aFriend = (Person) ite.next(); if (!inFriendCircle(aFriend, friendSet)) { System.out.print("--> " + aFriend.getFirstName() + "/" + aFriend.getLastName()); printFriendPath("--> ", aFriend, friendSet); } } System.out.println("  >>>"); } else { System.out.println("No root person found."); } long endTime = System.currentTimeMillis();