Save mongodb DBCollection to a file - Java Big Data

Java examples for Big Data:MongoDB

  1. HOME
  2. Java
  3. Big Data
  4. MongoDB

Description

Save mongodb DBCollection to a file

Demo Code




import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.OutputStreamWriter;
import java.io.Writer;

import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.MongoClient;

public class MongoRetrieve {
    public static void main(String args[]) {
        try {//from w w  w .j a v a2 s.c  om
            // To connect to mongodb server
            MongoClient mongoClient = new MongoClient("localhost", 27017);
            // Now connect to your databases
            DB db = mongoClient.getDB("testDB");
            System.out.println("Connect to database successfully");

            boolean auth = db.authenticate(myUserName, myPassword);
            System.out.println("Authentication: "+auth);     
            for (int ii = 0; ii < 26; ii++) {
                File file = new File((char) ('a' + ii) + ".txt");
                System.out.println(file.getAbsolutePath());
                System.out.println(file.getPath());

                if (!file.exists()) {
                    file.createNewFile();
                }
                //  FileWriter fw = new FileWriter(file.getAbsoluteFile());
                Writer out = new BufferedWriter(new OutputStreamWriter(
                        new FileOutputStream(file.getAbsoluteFile()),
                        "UTF-8"));

                //  BufferedWriter bw = new BufferedWriter(fw);

                DBCollection coll = db.getCollection("words_started_with_"
                        + (char) ('a' + ii));

                DBCursor cursor = coll.find();
                int i = 1;
                while (cursor.hasNext()) {
                    System.out.println("Inserted Document: "+i); 
                    out.write(cursor.next().toString() + "\n");
                    System.out.println(cursor.next()); 
                    i++;
                }
            }

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

}

Related Tutorials