mongodb java操作语法

之前都是通过spring-data框架来对mongodb操作，当然在很多老的项目中，由于jar包版本的问题，不太好升级到最新的版本，往往会采用mongodb-driver.jar直接来操作，下面我们就简单的介绍下一些常用的语法。

添加数据

collection.save(new BasicDBObject("author", "yinjihuan").append("title", "mongodb"));

编辑数据

collection.update(new BasicDBObject("author", "yinjihuan"), 
     new BasicDBObject("$set", new BasicDBObject("title", "mongodb3.0")));

删除数据

collection.remove(new BasicDBObject("author", "yinjihuan"));

查询所有数量

long count = collection.count();

查询所有数据

DBCursor cursor = collection.find();while (cursor.hasNext()) {      DBObject data = cursor.next();      System.out.println(data.toString());
}

查询第一条数据

DBObject data = collection.findOne();

带条件查询

DBObject query = new BasicDBObject("author", "yinjihuan");
cursor = collection.find(query);

大于（gt）查询

query = new BasicDBObject("visit_count", new BasicDBObject("$gt", 10));
cursor = collection.find(query);

小于（lt）查询

query = new BasicDBObject("visit_count", new BasicDBObject("$lt", 10));
cursor = collection.find(query);

查询固定的列

query = new BasicDBObject("author", "yinjihuan");
DBObject fields = new BasicDBObject("author", 1);
cursor = collection.find(query, fields);

分页查询,当数据量较大的时候不建议使用skip，会很慢的建议按id排序，每查询一页记住最后一条id,然后大于id在limit

query = new BasicDBObject("author", "yinjihuan");
cursor = collection.find(query, fields).skip(0).limit(10);

创建索引

collection.createIndex(new BasicDBObject("author_idx", 1));