mongodb的java driver执行“原生查询”语句

最新推荐文章于 2024-05-17 18:02:32 发布

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本文通过示例展示了如何使用MongoDB进行复杂查询及筛选操作，包括利用$or和$and逻辑运算符，以及使用$elemMatch进行数组条件匹配。通过实际案例，深入理解查询表达式在数据库操作中的应用。

DBObject o=(DBObject) JSON.parse("{ groups.groupName : 'group1' }");

DBObject o2=(DBObject) JSON.parse("{ groups.size : 0 }");

//这个格外的部分是 filed selection，为0你看结果里面就没有这个filed，如果为1则是只有这个filed被返回

DB db = new Mongo().getDB("test");
DBCollection coll = db.getCollection("UserInfo");
DBCursor cur = coll.find(o,o2).slaveOk(); //slaveOk是说在replica模式下，访问secondary（扶手）需要slaveOk while(cur.hasNext()){
System.out.println(cur.next());

}

==================result======================================================

{ "_id" : { "$oid" : "4e82e5fe6c7de47b217684a8"} , "className" : "vo.UserInfo" , "email" : "a@email.com" , "groups" : [ { "groupName" : "group1"} , { "groupName" : "group2"}]}
{ "_id" : { "$oid" : "4e82e6566c7d169e3e4873d7"} , "className" : "vo.UserInfo" , "email" : "a@email.com" , "groups" : [ { "groupName" : "group1"} , { "groupName" : "group2"}]}
{ "_id" : { "$oid" : "4e82e6c26c7d1f4ace2dfe29"} , "className" : "vo.UserInfo" , "email" : "a@email.com" , "groups" : [ { "groupName" : "group1"} , { "groupName" : "group2"}]}
{ "_id" : { "$oid" : "4e82e6e96c7d1fb39cf66eb4"} , "className" : "vo.UserInfo" , "email" : "a@email.com" , "groups" : [ { "groupName" : "group1"} , { "groupName" : "group2"}]}
{ "_id" : { "$oid" : "4e82e6fb6c7da5fa87fb8b13"} , "className" : "vo.UserInfo" , "email" : "a@email.com" , "groups" : [ { "groupName" : "group1"} , { "groupName" : "group2"}]}
{ "_id" : { "$oid" : "4e82e74c6c7d653edb297c32"} , "className" : "vo.UserInfo" , "email" : "a@email.com" , "groups" : [ { "groupName" : "group1"} , { "groupName" : "group2"}]}
{ "_id" : { "$oid" : "4e82ea436c7da72043cf2e4c"} , "className" : "vo.UserInfo" , "email" : "a@email.com" , "groups" : [ { "groupName" : "group1"} , { "groupName" : "group2"}]}