详解MongoDB数据库基础操作及实例

/** 
 * 插入一条DB对象 
 */ 
public static void addDBObject(DBCollection collection,BasicDBObject object){ 
  collection.insert(object); 
} 
 
/** 
 * 根据id查询DBObject 
 */ 
public static DBObject getDBObjectById(String value) throws UnknownHostException, MongoException{ 
  dbc = getDBCollection("company", "users").find(new BasicDBObject("_id",new ObjectId(value))); 
  DBObject ob = null; 
  int i = 0; 
  while(dbc.hasNext()){ 
    ob = dbc.next(); 
    i++; 
  } 
  if(i == 1){ 
    return ob; 
  }else{ 
    return null; 
  } 
} 
 
/** 
 * 根据key和value值查询 
 */ 
public static DBObject getDBObject(String key,String value) throws UnknownHostException, MongoException{ 
  dbc = getDBCollection("company", "users").find(new BasicDBObject(key,value)); 
  DBObject ob = null; 
  int i = 0; 
  while(dbc.hasNext()){ 
    ob = dbc.next(); 
    i++; 
  } 
  if(i == 1){ 
    return ob; 
  }else{ 
    return null; 
  } 
} 
 
/** 
 * 根据数据库名获取(新增)下面所有聚集名（表名） 
 */ 
public static Set getCollectionsNames(String DBName) throws MongoException, UnknownHostException{ 
  return getDB(DBName).getCollectionNames(); 
} 
 
/** 
 * 遍历聚集中的db对象集合(相当于关系数据库中的数据) 
 */ 
public static Set getDBObjects(DBCollection collection){ 
  Set dbObjects = new HashSet(); 
  DBCursor cursor = collection.find(); 
  while(cursor.hasNext()){ 
    DBObject object = cursor.next(); 
    dbObjects.add(object); 
  } 
  return dbObjects; 
} 
 
/** 
 * 获取/新增聚集（相当于关系数据库表） 
 */ 
public static DBCollection getDBCollection(String DBName,String collectionName) throws UnknownHostException, MongoException{ 
  return getDB(DBName).getCollection(collectionName); 
} 
 
/** 
 * 获取/新增数据库 
 */ 
public static DB getDB(String DBName) throws UnknownHostException, MongoException{ 
  return getMongo().getDB(DBName); 
} 
 
/** 
 * 连接数据库 
 */ 
public static Mongo getMongo() throws UnknownHostException, MongoException{ 
  Mongo mg = null; 
  if(mg == null){ 
    mg = new Mongo(); 
  } 
  return mg; 
} 
 
/** 
 * 关闭连接 
 */ 
public static void destory(Mongo mg) { 
  if (mg != null){ 
    mg.close(); 
    mg = null;  
  } 
  System.gc();   
} 
 
/** 
 * 获取数据库名 
 */ 
public static List getDBNames() throws MongoException, UnknownHostException{ 
  return getMongo().getDatabaseNames(); 
} 
 
/** 
 * 删除数据库 
 */ 
public static void deleteDB(String DBName) throws MongoException, UnknownHostException{ 
  getMongo().dropDatabase(DBName); 
}