公開分佈式高性能查詢的源代碼和部署方案(三）

7）Versant數據庫的對象查詢 Versant數據庫能夠支持SQL查詢和NOSQL查詢兩種模式，如下爲在查到第一個目標對象，以後採用NOSQL方式，自動執行朋友圈子遍歷的例子： 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(); // 建立已經走過的朋友路徑，避免迴環 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();