MongoDB番外篇

rs.slaveOk()//在从主机访问数据设置的时候要先执行这句，因为主从模式下为了避免主从节点的数据不一致的问题，从节点是不能查看以及修改数据的，必须执行这句之后才可以。
mongod --dbpath /usr/local/mongodb/mongodb/data/db/ --slave --source=192.168.1.202:27017 –autoresync//参数autoresync参数为了是强制从节点同步主节点的数据
db.table.createIndex({"id":"hashed"})//创建索引
db.table.getIndexes()//默认在id字段上有索引，创建索引后则应该有两个索引才对。
db.table.ensureIndex({"somefield"：1}，"background":true)//在后台建立索引

   Mongo m = new Mongo( "192.168.21.111" , 27017 );  
            //选择数据库，如果没有这个数据库的话，会自动建立  
            DB  db = m.getDB( "mydb" );  
              DBCollection collection = db.getCollection("myCollectionTest");  

            BasicDBObject doc = new BasicDBObject(); //文档或者可以看作是k-v记录集 
            doc.put("name", "MongoDB");  
            doc.put("type", "database");  
            doc.put("count", 1);  

            BasicDBObject info = new BasicDBObject();  
            info.put("x", 203);  
            info.put("y", 102);  
            doc.put("info", info);  

            //插入一条数据,数据如下  
            // {  
            //     "name" : "MongoDB",  
            //     "type" : "database",  
            //     "count" : 1,  
            //     "info" : {  
            //                 x : 203,  
            //                 y : 102  
            //               }  
            //  }  
            // 可以循环插入多条数据  
            collection.insert(doc);  
            //查找第一条数据,显示如下，_id是系统自动帮加上的，全局唯一  
            //{ "_id" : "49902cde5162504500b45c2c" , "name" : "MongoDB" , "type" : "database" , "count" : 1 , "info" : { "x" : 203 , "y" : 102}}  
            DBObject myDoc = collection.findOne();  
            System.out.println(myDoc);  

            //插入多条数据  
            for (int i=0; i < 100; i++) {  
                collection.insert(new BasicDBObject().append("i", i));  
            } 
            //获取文档条数  
            System.out.println(collection.getCount());  

            //使用Cursor 获取所有文档  
            DBCursor cursor = collection.find();  
            try {  
                while(cursor.hasNext()) {  
                    System.out.println(cursor.next());  
                }  
            } finally {  
                cursor.close();  
            }  

            //查找操作，获取单条记录  
            //{ "_id" : "49903677516250c1008d624e" , "i" : 71 }  
            BasicDBObject query = new BasicDBObject();  
            query.put("i", 71);  
            cursor = collection.find(query);  
            try {  
                while(cursor.hasNext()) {  
                    System.out.println(cursor.next());  
                }  
            } finally {  
                cursor.close();  
            }  

            //查找 i>50的项  
            query = new BasicDBObject();  
            query.put("i", new BasicDBObject("$gt", 50));  // e.g. find all where i > 50  
            cursor = collection.find(query);  
            try {  
                while(cursor.hasNext()) {  
                    System.out.println(cursor.next());  
                }  
            } finally {  
                cursor.close();  
            }  


            //查找 20<i<=30  
            query = new BasicDBObject();  
            query.put("i", new BasicDBObject("$gt", 20).append("$lte", 30));  // i.e.   20 < i <= 30  
            cursor = collection.find(query);  
            try {  
                while(cursor.hasNext()) {  
                    System.out.println(cursor.next());  
                }  
            } finally {  
                cursor.close();  
            }  

            //修改 i=71的一项  
            query = new BasicDBObject();  
            query.put("i", 71);  
            BasicDBObject update = new BasicDBObject();  
            update.put("i", 710);  
            DBObject dbobj = collection.findAndModify(query, update);  
            System.out.println(dbobj);  

            //修改 i=72的一项  
            query = new BasicDBObject();  
            query.put("i", 72);  
            update = new BasicDBObject();  
            update.put("i", 720);  
            WriteResult result = collection.update(query, update);  
            System.out.println(result);  

            //删除i=61的项  
            query = new BasicDBObject();  
            query.put("i", 61);  
            collection.findAndRemove(query);  
            //删除i=62的项  
            BasicDBObject remove = new BasicDBObject();  
            remove.put("i", 62);  
            collection.remove(remove);  

            //创建索引 1为升序、-1为降序  
            collection.createIndex(new BasicDBObject("i", 1));  // create index on "i", ascending  

            //获取索引列表  
            List<DBObject> list = collection.getIndexInfo();  
            for (DBObject o : list) {  
                System.out.println(o);  
            }  

            //获取数据库列表  
            for (String s : m.getDatabaseNames()) {  
                System.out.println(s);  
            }  
            //获取集合列表  
            Set<String> colls = db.getCollectionNames();  
            for (String s : colls) {  
                System.out.println(s);  
            }  

            //删除数据库  
            //m.dropDatabase("my_new_db");  


        } catch (UnknownHostException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }  
    }