mongodb中的$or 操作符用java代码来实现

在mongodb中有$or 操作符的，官网中给出的例子如下：

 

Simple:

db.foo.find( { $or : [ { a : 1 } , { b : 2 } ] } )

With another field

db.foo.find( { name : "bob" , $or : [ { a : 1 } , { b : 2 } ] } )

The $or operator retrieves matches for each or clause individually and eliminates duplicates when returning results. A number of $or optimizations are planned for 1.8. See this thread for details.

$or cannot be nested.

在java中怎么用代码来实现？？？？  请看下面~~

DBObject ref = new BasicDBObject();

BasicDBObject or1 = new BasicDBObject();

or1.put("id1", 1);

BasicDBObject or2 = new BasicDBObject();

or2.put("id1", 2);

BasicDBObject or3 = new BasicDBObject();

or3.put("id2", 1);

ArrayList<DBObject> list = new ArrayList<DBObject>();

list.add(or1);

list.add(or2);

list.add(or3);

BasicDBObject query = new BasicDBObject();

query.put("$or", list);

DBCursor res =coll.find(query);

System.out.println("res = "+res);

while(res.hasNext()){

DBObject dbo = res.next();

System.out.println("dbo = "+dbo);

}