詳解數據庫基礎操作及實例

          廢話不多說，直接上代碼，注釋寫的比較清楚，大家參考下，

 示例代碼：

/** 
 * 插入一條DB對象 
 */ 
public static void addDBObject(DBCollection collection,BasicDBObject object){ 
  collection.insert(object); 
} 
 
/** 
 * 根據id查詢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; 
  } 
} 
 
/** 
 * 根據key和value值查詢 
 */ 
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; 
  } 
} 
 
/** 
 * 根據數據庫名獲取(新增)下面所有聚集名（表名） 
 */ 
public static Set<String> getCollectionsNames(String DBName) throws MongoException, UnknownHostException{ 
  return getDB(DBName).getCollectionNames(); 
} 
 
/** 
 * 遍歷聚集中的db對象集合(相當于關系數據庫中的數據) 
 */ 
public static Set<DBObject> getDBObjects(DBCollection collection){ 
  Set<DBObject> dbObjects = new HashSet<DBObject>(); 
  DBCursor cursor = collection.find(); 
  while(cursor.hasNext()){ 
    DBObject object = cursor.next(); 
    dbObjects.add(object); 
  } 
  return dbObjects; 
} 
 
/** 
 * 獲取/新增聚集（相當于關系數據庫表） 
 */ 
public static DBCollection getDBCollection(String DBName,String collectionName) throws UnknownHostException, MongoException{ 
  return getDB(DBName).getCollection(collectionName); 
} 
 
/** 
 * 獲取/新增數據庫 
 */ 
public static DB getDB(String DBName) throws UnknownHostException, MongoException{ 
  return getMongo().getDB(DBName); 
} 
 
/** 
 * 連接數據庫 
 */ 
public static Mongo getMongo() throws UnknownHostException, MongoException{ 
  Mongo mg = null; 
  if(mg == null){ 
    mg = new Mongo(); 
  } 
  return mg; 
} 
 
/** 
 * 關閉連接 
 */ 
public static void destory(Mongo mg) { 
  if (mg != null){ 
    mg.close(); 
    mg = null;  
  } 
  System.gc();   
} 
 
/** 
 * 獲取數據庫名 
 */ 
public static List<String> getDBNames() throws MongoException, UnknownHostException{ 
  return getMongo().getDatabaseNames(); 
} 
 
/** 
 * 刪除數據庫 
 */ 
public static void deleteDB(String DBName) throws MongoException, UnknownHostException{ 
  getMongo().dropDatabase(DBName); 
}