MongoDB Command Line group grouping and group grouping in Java code

Group grouping statistics is a common function of database, MongoDB is no exception. However, relative to the normal additions and deletions, the group operation is a little more trouble, here to the group in the shell operation, the use of Java native Code operation and integration of spring operation to a simple summary, the grouping of ways and methods should have a variety of, here each one only to cite one example.
The data source in this example is as follows:

The purpose of the group implementation is to count the number of each group by age group.
1. Execute the following command in the MONGO Shell:

Db.test.group ({    key:{"age": 1},    initial:{"Count": 0},   $reduce: function (doc,out) {out.count++;},   $ Finalize:function (out) {return out;}} )

Execute code and Results

2, Java native code to do the above:

public class Montest {public static void main (string[] args) {mongroup ();        public static void Mongroup () {serveraddress sa = new ServerAddress ("192.168.0.201", 37017);        list<mongocredential> mongocredentiallist = new arraylist<mongocredential> ();        Mongocredentiallist.add (mongocredential.createmongocrcredential ("admin", "admin", "123456". ToCharArray ()));        Mongo client = new Mongoclient (SA, mongocredentiallist);        DB database = Client.getdb ("admin");        Dbcollection coll = database.getcollection ("test");        DBObject keys = new Basicdbobject ("Age", 1);        DBObject condition = null;        DBObject initial = new Basicdbobject ("Count", 0);        String reduce = "function (doc,out) {out.count++;}";        String Finalize = "function" {return out;} ";        Basicdblist dblist = (basicdblist) coll.group (keys, condition, initial, reduce, finalize); if (dblist! = null) {for (int i = 0; i < dblist.siZe ();                i++) {DBObject obj = (dbobject) dblist.get (i);                Object age = Obj.get ("Age");                Object count = Obj.get ("Count");            System.out.println ("Age:" + Age + ", Count:" + count); }        }    }}

Execution results

3. Operation after integration with spring:
Environment construction can be consulted: http://blog.csdn.net/tuzongxun/article/details/51404529
Dao Method implementation code:

  /**     * MongoDB Simple packet Query     *      * @author: Tuzongxun     * @Title: Mongogroup     * @param @return     * @date Jul 19, 8:36:19 AM     * @throws *    /@Override public    basicdblist Mongogroup () {        //TODO auto-generated Method Stub        GroupBy GroupBy = Groupby.key ("Age"). Initialdocument ("{count:0}"). Reducefunction ("function (Doc, Out) {out.count++} ')            . Finalizefunction ("function (out) {return out;}");        groupbyresults<usermodel> res = mongotemplate.group ("Test", GroupBy, Usermodel.class);        DBObject obj = Res.getrawresults ();        Basicdblist dblist = (basicdblist) obj.get ("RetVal");        return dblist;    }

The corresponding entity model:

Package Spring_mongo.models;import Java.io.serializable;public class Usermodel implements Serializable {    private Static final Long serialversionuid = 1L;    private String name;    private int age;    Public Usermodel (String name, Int. age) {        super ();        this.name = name;        This.age = age;    }    Public String GetName () {        return name;    }    public void SetName (String name) {        this.name = name;    }    public int getage () {        return age;    }    public void Setage (int.) {        this.age = age;    }    @Override public    String toString () {        return ' Usermodel [name= "+ name +", age= "+ Age +"] ";    }}

JUnit test methods:

@Test public    void Mongogroup () {        basicdblist dblist = Userdao.mongogroup ();        if (dblist! = null) {for            (int i = 0; i < dblist.size (); i++) {                DBObject obj = (dbobject) dblist.get (i);                Object age = Obj.get ("Age");                Object count = Obj.get ("Count");                System.out.println ("Age:" + Age + ", Count:" + count);}}}    

Run results

MongoDB Command Line group grouping and group grouping in Java code