package mymaven;  import java.net.UnknownHostException;  import java.util.Set;  import com.mongodb.BasicDBObject;  import com.mongodb.DB;  import com.mongodb.DBCollection;  import com.mongodb.DBCursor;  import com.mongodb.DBObject;  import com.mongodb.Mongo;  import com.mongodb.MongoException;  public class Test {      public static void main(String[] args) throws UnknownHostException, MongoException {          Mongo mongo = new Mongo("172.27.9.104", 27017);     // 连接数据库          DB db = mongo.getDB("mytestdb");                    // 数据库          Set<String> cols = db.getCollectionNames();           // 获取数据库中所有的集合（类似于获取关系数据库中的表）          // 打印出数据库中的集合，这里应当为null          for (String s : cols) {              System.out.println(s);          }          DBCollection collection = db.getCollection("mytestcoll");       // 创建一个集合          collection.drop();                                              // 删除集合，插入数据时自动重建          BasicDBObject obj = new BasicDBObject();                        // 初始化一个基本DB对象，插入数据库的就是DB对象          obj.put("from", "blog.ithomer.net");        // 放入几个键值对          obj.put("to", "forum.ithomer.net");          obj.put("subject", "ithomer.net");          collection.insert(obj);                     // 插入对象          DBObject dbobj = collection.findOne();      // 查看一条记录，findOne()=find().limit(1);          System.out.println(dbobj);                  // 打印出刚才插入的数据          // 插入10条{ranking:i}的数据          for (int i = 0; i < 10; i++) {              collection.insert(new BasicDBObject().append("ranking", i));          }          System.out.println("count: " + collection.getCount());      // 打印集合中的数据总数                    DBCursor cursor = collection.find();        // 然后我们使用这个游标来遍历集合          while (cursor.hasNext()) {              System.out.println(cursor.next());          }          // 简单的条件查询，查询ranking为1的记录          BasicDBObject query = new BasicDBObject();          query.put("ranking", 1);          cursor = collection.find(query);          System.out.println("collection find({"ranking":1}):");          while (cursor.hasNext()) {              System.out.println(cursor.next());          }          // 复杂的条件查询，查询ranking大于等于5小于9的记录          query = new BasicDBObject();          query.put("ranking", new BasicDBObject("$gte", 5).append("$lt", 9));          cursor = collection.find(query);          System.out.println("collection find({"ranking":[5-9)}):");          while (cursor.hasNext()) {              System.out.println(cursor.next());          }  //      mongo.dropDatabase("mytestdb");         // 最后删除我们的测试数据库      }  } 

mytestcoll system.indexes { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10107"} , "from" : "blog.ithomer.net" , "to" : "forum.ithomer.net" , "subject" : "ithomer.net"} count: 11 { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10107"} , "from" : "blog.ithomer.net" , "to" : "forum.ithomer.net" , "subject" : "ithomer.net"} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10108"} , "ranking" : 0} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10109"} , "ranking" : 1} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010a"} , "ranking" : 2} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010b"} , "ranking" : 3} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010c"} , "ranking" : 4} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010d"} , "ranking" : 5} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010e"} , "ranking" : 6} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010f"} , "ranking" : 7} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10110"} , "ranking" : 8} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10111"} , "ranking" : 9} collection find({"ranking":1}): { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10109"} , "ranking" : 1} collection find({"ranking":[5-9)}): { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010d"} , "ranking" : 5} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010e"} , "ranking" : 6} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010f"} , "ranking" : 7} { "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10110"} , "ranking" : 8}

 @SuppressWarnings("unchecked")  public static void loadMediaTags(List<MediaEntity> mediaEntityList) {   mediaEntityList.clear();   try {    Mongo mongo = new Mongo(CosineCluster.gMongo_HOST, CosineCluster.gMongo_PORT);    DB db = mongo.getDB(CosineCluster.gMongo_DB);    DBCollection collection = db.getCollection(CosineCluster.gMongo_Coll_Media);    DBCursor cursor = collection.find();    int index = 0;    long startTime = System.currentTimeMillis();    while(cursor.hasNext()){     BasicDBObject obj = (BasicDBObject) cursor.next();     long id = obj.getLong("_id");     ArrayList<String> tagList = (ArrayList<String>) obj.get("tag");     // tag     ArrayList<String> keywordList = (ArrayList<String>)obj.get("keyword");   // keyword     ArrayList<Integer> copyrightList = (ArrayList<Integer>)obj.get("copyright"); // copyright        MediaEntity mediaEntity = new MediaEntity();     mediaEntity.setId(id);     // tag     for(int j=0; j<tagList.size(); j++) {      mediaEntity.addTag(tagList.get(j));      int tagId = getTagInt(tagList.get(j));      mediaEntity.addTag(tagId);     }     // actors     ArrayList<DBObject> actorsObjList = (ArrayList<DBObject>)obj.get("actors");  // actors     for(int j=0; j<actorsObjList.size(); j++) {       mediaEntity.addActor((String) actorsObjList.get(j).get("name"));        int actorId = getActorInt((String)actorsObjList.get(j).get("name"));       mediaEntity.addActor(actorId);     }     // director     ArrayList<DBObject> directorObjList = (ArrayList<DBObject>)obj.get("director"); // director     for(int j=0; j<directorObjList.size(); j++) {       mediaEntity.addDirector((String) directorObjList.get(j).get("name"));        int directorId = getDirectorInt((String) directorObjList.get(j).get("name"));       mediaEntity.addDirector(directorId);     }     // keyword     for(int j=0; j<keywordList.size(); j++) {      mediaEntity.addKeyword(keywordList.get(j));      int keywordId = getKeywordInt(keywordList.get(j));      mediaEntity.addKeyword(keywordId);     }     // copyright     for(int j=0; j<copyrightList.size(); j++) {      mediaEntity.addCopyright(copyrightList.get(j));     }     mediaEntityList.add(mediaEntity);     index++;     if(index > 100) {      break;     }     System.out.println(index + " --- mediaEntity : " + mediaEntity.toString());    }    long costTime = System.currentTimeMillis() - startTime;    System.out.println("load data costTime = " + index + "; costTime = " + costTime/1000f);   } catch (Exception e) {    e.printStackTrace();   }  }  public static int getTagInt(String tag) {   int tagIntId = -1;   try {    MongoClient mongo = new MongoClient(CosineCluster.gMongo_HOST, CosineCluster.gMongo_PORT);    DB db = mongo.getDB(CosineCluster.gMongo_DB);    DBCollection tagmapCollection = db.getCollection("recommend_tag_map");    DBCursor cursor = tagmapCollection.find(new BasicDBObject("name", tag));     if(cursor == null || cursor.toArray().size() <= 0) {  // 处理小于2或n的映射关键字，下同     return tagIntId;    }    DBObject obj = cursor.toArray().get(0);        String name = tag;    tagIntId = (Integer) obj.get("id");    int num = (Integer) obj.get("num");    mongo.close();   } catch (UnknownHostException e) {    e.printStackTrace();   }   return tagIntId;  }  public static int getActorInt(String actor) {   int actorIntId = -1;   try {    MongoClient mongo = new MongoClient(CosineCluster.gMongo_HOST, CosineCluster.gMongo_PORT);    DB db = mongo.getDB(CosineCluster.gMongo_DB);    DBCollection tagmapCollection = db.getCollection("recommend_actor_map");    DBCursor cursor = tagmapCollection.find(new BasicDBObject("name", actor));    if(cursor == null || cursor.toArray().size() <= 0) {     return actorIntId;    }    DBObject obj = cursor.toArray().get(0);    String name = actor;    actorIntId = (Integer) obj.get("id");    int num = (Integer) obj.get("num");    mongo.close();   } catch (UnknownHostException e) {    e.printStackTrace();   }   return actorIntId;  }