MongoDB java组/计数功能

我是MongoDB的新手，我必须使用jsp/servlet创建简单的站点。MongoDB java组/计数功能

我需要一个创建查询，将返回一些网站已被访问的次数。

我的DB是这样的：

{ "_id" : { "$oid" : "5117fa92f1d3a4093d0d3902"} , "ip" : "127.0.0.1" , "datum" : { "$date" : "2013-02-10T19:52:50.051Z"} , "odlaznaStr" : "localhost:8080/mongoProjekat/" , "dolaznaStr" : "localhost:8080/mongoProjekat/treca"}<br> 
{ "_id" : { "$oid" : "5117fa92f1d3a4093d0d3903"} , "ip" : "127.0.0.1" , "datum" : { "$date" : "2013-02-10T19:52:50.796Z"} , "odlaznaStr" : "localhost:8080/mongoProjekat/treca.jsp" , "dolaznaStr" : "localhost:8080/mongoProjekat/peta"}<br> 
{ "_id" : { "$oid" : "5117fa93f1d3a4093d0d3904"} , "ip" : "127.0.0.1" , "datum" : { "$date" : "2013-02-10T19:52:51.141Z"} , "odlaznaStr" : "localhost:8080/mongoProjekat/peta.jsp" , "dolaznaStr" : "localhost:8080/mongoProjekat/treca"}<br> 
{ "_id" : { "$oid" : "5117fa93f1d3a4093d0d3905"} , "ip" : "127.0.0.1" , "datum" : { "$date" : "2013-02-10T19:52:51.908Z"} , "odlaznaStr" : "localhost:8080/mongoProjekat/treca.jsp" , "dolaznaStr" : "localhost:8080/mongoProjekat/cetvrta"}<br> 
{ "_id" : { "$oid" : "5117fa94f1d3a4093d0d3906"} , "ip" : "127.0.0.1" , "datum" : { "$date" : "2013-02-10T19:52:52.035Z"} , "odlaznaStr" : "localhost:8080/mongoProjekat/treca.jsp" , "dolaznaStr" : "localhost:8080/mongoProjekat/cetvrta"}<br> 
{ "_id" : { "$oid" : "5117fa94f1d3a4093d0d3907"} , "ip" : "127.0.0.1" , "datum" : { "$date" : "2013-02-10T19:52:52.197Z"} , "odlaznaStr" : "localhost:8080/mongoProjekat/cetvrta.jsp" , "dolaznaStr" : "localhost:8080/mongoProjekat/treca"}

我需要的是一个结果，这将是这个样子：

page: localhost:8080/mongoProjekat/treca visited: n(times)<br> 
page: localhost:8080/mongoProjekat/druga visited: n(times)

...等等为每个已被访问页面。

我正在使用Java。

来源

2013-02-10 toskebre

看看['DBCollection.aggregate'（http://api.mongodb.org/java/current/），提供了访问蒙戈的[聚合框架] （http://docs.mongodb.org/manual/applications/aggregation/）来处理这样的查询。 – JohnnyHK 2013-02-10 20:34:59

你可能会发现这个SQL到MongoDB图表http://docs.mongodb.org/manual/reference/sql-aggregation-comparison/有帮助。

至于你直接的问题：

// getCollection 

    DBCollection myColl = db.getCollection("toskebre"); 

    // for the $group operator 
    // note - the collection still has the field name "dolaznaStr" 
    // but, to we access "dolaznaStr" in the aggregation command, 
    // we add a $ sign in the BasicDBObject 

    DBObject groupFields = new BasicDBObject("_id", "$dolaznaStr"); 

    // we use the $sum operator to increment the "count" 
    // for each unique dolaznaStr 
    groupFields.put("count", new BasicDBObject("$sum", 1)); 
    DBObject group = new BasicDBObject("$group", groupFields); 


    // You can add a sort to order by count descending 

    DBObject sortFields = new BasicDBObject("count", -1); 
    DBObject sort = new BasicDBObject("$sort", sortFields); 


    AggregationOutput output = myColl.aggregate(group, sort); 

    System.out.println(output.getCommandResult());

中的println会打印：

{ "serverUsed" : "localhost/127.0.0.1:27017" , 
    "result" : [ { "_id" : "localhost:8080/mongoProjekat/treca" , "count" : 3} , 
       { "_id" : "localhost:8080/mongoProjekat/cetvrta" , "count" : 2} , 
       { "_id" : "localhost:8080/mongoProjekat/peta" , "count" : 1}] , 
    "ok" : 1.0}

来源

2013-02-11 15:43:10 Kay

泰的答案凯。我已经找到与您的解决方案类似的解决方案。我已经做了这种方式：

 DBObject match = new BasicDBObject("stranica","$dolaznaStr"); 
    DBObject project = new BasicDBObject("$project",match); 

    DBObject id = new BasicDBObject("_id",new BasicDBObject("stranica","$stranica")); 
    id.put("posete", new BasicDBObject("$sum", 1)); 
    DBObject group = new BasicDBObject("$group",id); 

    DBObject srt = new BasicDBObject("posete",-1); 
    DBObject sort = new BasicDBObject("$sort", srt); 
    AggregationOutput ao = collection.aggregate(project, group, sort);

来源

2013-02-11 17:26:21 toskebre

MongoDB java组/计数功能

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