一个mongo聚合数据的例子

function statisticsSchoolForTimes(nowtime) {
db.getCollection('all').aggregate(
[
{$match:{"time":nowtime}},
{
$group:{
_id:{"schoolId":"$schoolId","userRole":"$userRole"},
provinceCode:{$first:"$provinceCode"},
provinceValue:{$first:"$provinceValue"},
cityValue:{$first:"$cityValue"},
cityCode:{$first:"$cityCode"},
countyCode:{$first:"$countyCode"},
countyValue:{$first:"$countyValue"},
schoolLevel:{$first:"$schoolLevel"},
schoolName:{$first:"$schoolName"},
schoolId:{$first:"$schoolId"},
time:{$first:"$time"},
userRole:{$first:"$userRole"}
}
}
]).forEach(function(x){
var praiseNum=db.getCollection('all').find({"schoolId":x.schoolId,"time":x.time,"type":"praise","userRole":x.userRole}).count();
var downloadNum=db.getCollection('all').find({"schoolId":x.schoolId,"time":x.time,"type":"download","userRole":x.userRole}).count();
var collectionNum=db.getCollection('all').find({"schoolId":x.schoolId,"time":x.time,"type":             "collection","userRole":x.userRole}).count();
var commentNum=db.getCollection('all').find({"schoolId":x.schoolId,"time":x.time,"type":"comment","userRole":x.userRole}).count();
var browseNum=db.getCollection('all').find({"schoolId":x.schoolId,"time":x.time,"type":"browse","userRole":x.userRole}).count();
db.getCollection('school').insert(x);
db.getCollection('school').update({"schoolId":x.schoolId,"time":x.time,"userRole":x.userRole},{'$set': {'praiseNum': praiseNum,'downloadNum': downloadNum,'collectionNum': collectionNum,'commentNum': commentNum,'browseNum': browseNum}});
})
}

private static SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

public void run() {
try {
System.out.println("开始数据统计聚合任务，时间为："+formatter.format(Calendar.getInstance().getTime()));
aggregate();
System.out.println("结束数据统计聚合任务，时间为："+formatter.format(Calendar.getInstance().getTime()));
} catch (Exception e) {
System.out.println("-------------数据统计聚合任务发生异常--------------"+e.toString());
}
}

public static void aggregate(){
System.out.println("开始数据统计聚合任务，时间为："+formatter.format(Calendar.getInstance().getTime()));
MongoUtils mu = new MongoUtils();
MongoUtils.createMongoClient();
DB db=mu.getDB(MongoUtils.DATABASE);
String nowTime = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
db.eval("statisticsDistrictForTimes('"+nowTime+"')");
db.eval("statisticsSchoolForTimes('"+nowTime+"')");
mu.closeConnection();
System.out.println("结束数据统计聚合任务，时间为："+formatter.format(Calendar.getInstance().getTime()));
}