MongoDB: JSON vs. BSON

01_mongoshell.js

use test

db.foo.drop();
// in JSON all numbers are 32-bit floating point types (s. JSON spec) 
// and thus are mapped to the 64-bit floating point type in BSON
db.foo.insert( {a: 1} )

02_javaclient.java

import java.net.UnknownHostException;

import com.mongodb.DBObject;
import com.mongodb.Mongo;

public class JsonVsBson {
  
	public static void main(String argv[]) throws UnknownHostException {

		DBObject doc = new Mongo().getDB("test").getCollection("foo").findOne();
		System.out.println( doc.get("a") );
		System.out.println( doc.get("a") instanceof Double);
		
	}
	
}

03_output.txt

1.0
true