详解数据库基础操作及实例

废话不多说，直接上代码，注释写的比较清楚，大家参考下，

示例代码：

/** * 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<String> 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<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; } /** * 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<String> getDBNames() throws MongoException, UnknownHostException{ return getMongo().getDatabaseNames(); } /** * 删除数据库 */ public static void deleteDB(String DBName) throws MongoException, UnknownHostException{ getMongo().dropDatabase(DBName); }

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