Run my mongodb command from java program

Question

How to run multiple mongodb commands from a java code. I need the mongodb commands to get executed in background when i run the java program. This program throws some exception "Exception in thread "main" java.io.IOException: Cannot run program "db.createCollection("employ")": error=2, No such file or directory at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029) . . .".

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class try1
{

    public static void main(String[] args) throws Exception{

        String command ="mongo";
        String command1="db.createCollection(\"employ\")";
        Process proc = Runtime.getRuntime().exec(command);
        Process proc1 = Runtime.getRuntime().exec(command1);

        BufferedReader reader =  
              new BufferedReader(new InputStreamReader(proc.getInputStream()));
        String line = "";
        while((line = reader.readLine()) != null) {
            System.out.print(line + "\n");
        }
        proc.waitFor();   

        BufferedReader reader1 =  
              new BufferedReader(new InputStreamReader(proc.getInputStream()));
        String line1 = "";
        while((line1 = reader1.readLine()) != null) {
            System.out.print(line1 + "\n");
        }
        proc1.waitFor(); 
    }
}

I need to run a set of mongo db commands from the java program. The program works with other terminal commands like "ls"(only single command). But there is problem if we give both command1 and command as "ls". Only one ls command gets executed. If trying with only one mongo db command say, "mongo" command does not get executed completely(program does not terminate). Is it because of "proc.waitFor()".

You are aware of the fact that there is a Java Driver for MongoDB? — Markus W Mahlberg
– Markus W Mahlberg, Commented Feb 23, 2016 at 1:51
yes i'm aware of that. But isnt there some other way? Like the code I have written. Using terminal commands. So that I can use the same query. — Mira
– Mira, Commented Feb 26, 2016 at 10:19
You'd be sacrificing a lot of performance for developer convenience. — Markus W Mahlberg
– Markus W Mahlberg, Commented Feb 26, 2016 at 11:22

Mira · Accepted Answer · 2016-04-01 08:42:46Z

2

i got the code. db.eval() function serves my purpose. It works perfectly. :) "query" is the String which stores the mongodb query.

 public  void qexecute()
        {
        try{String query="db.products.insert( { item: "card", qty: 15 } )";
              MongoClient mongo = new MongoClient("localhost",27017);
              DB db = mongo.getDB("test");
              DBCollection collection = db.getCollection(tablename);  
              db.eval(query);   
             }
          catch(UnknownHostException e){
              System.out.println(e);
           }
           catch (MongoException.DuplicateKey e) {
              System.out.println("Exception Caught" + e);
           }
    }

answered Apr 1, 2016 at 8:42

Mira

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Comments

Andrea Girardi · Accepted Answer · 2016-02-23 08:56:55Z

I strongly recommend to use Mongo Spring Data. You can do that:

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBCollection {

public static void main(String args[]) {

    try {

        //Connect to Database
        MongoClient mongoClient = new MongoClient("localhost",27017);
        DB db = mongoClient.getDB("myDB");
        System.out.println("Your connection to DB is ready for Use::"+db);

        //Create Collection
        DBCollection linked = db.createCollection("employ",new BasicDBObject()); 
        System.out.println("Collection employ created successfully");

    } catch(Exception e) {
        System.out.println(e.getClass().getName() + ": " + e.getMessage());
    }

}

}

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