Perform CRUD Operation's MongoDB with Java.

MongoDB :

Data in MongoDB has a flexible schema. Collections do not enforce document structure. This means that:

• documents in the same collection do not need to have the same set of fields or structure, and

• common fields in a collection’s documents may hold different types of data.

Each document only needs to contain relevant fields to the entity or object that the document represents. In practice, most documents in a collection share a similar structure. Schema flexibility means that you can model your documents in MongoDB so that they can closely resemble and reflect application-level objects. For more information Click on that link.

Requirements : 

1. Download MongoDB from here.
2. Install MongoDB and set the PATH variable . 
3. Install JDK 7 (The following code is Tested On JDK 7.

Note: Before Running the code, Need to start MongoDB server .

Following is the CODE to perform CRUD operation's of MongoDB with JAVA.

import java.net.UnknownHostException;

import java.util.Arrays;

import java.util.Date;

import org.bson.types.ObjectId;

import com.mongodb.BasicDBObject;

import com.mongodb.DB;

import com.mongodb.DBCollection;

import com.mongodb.DBCursor;

import com.mongodb.DBObject;

import com.mongodb.MongoClient;

import com.mongodb.QueryBuilder;

import com.mongodb.ServerAddress;

public class MongoDBCRUDOperationInJava {

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

  MongoClient client = new MongoClient(new ServerAddress("localhost", 27017));

  DB courseDB = client.getDB("students");

  DBCollection collection = courseDB.getCollection("grades");

  //collection.drop();

  //insertDocument(collection);

  //findOne(collection);

  //findAll(collection);

  //count(collection);

  //findWithCriteriaUsingDBObject(collection);

  findWithCriteriaUsingQueryBuilder(collection);

}

public static void insertDocument(DBCollection collection) {

 DBObject doc = new BasicDBObject("_id", new ObjectId());

 doc.put("name", "Harmeet");

 doc.put("age", 24);

 doc.put("birthday", new Date(12312312313l));

 doc.put("programmer", true);

 doc.put("language", Arrays.asList("Java", "Scala", "Python"));

 doc.put("address", new BasicDBObject("street", "5").append("area", "moga"));

 DBObject doc2 = new BasicDBObject().append("name", "Jimmy");

System.out.println("Before Inserting the Document in Collection : "+doc);

 collection.insert(Arrays.asList(doc, doc2));

 System.out.println("After Inserting the Document in Collection : "+doc);

}

public static void findOne(DBCollection collection) {

 DBObject doc = collection.findOne();

 System.out.println(doc);

}

public static void findAll(DBCollection collection) {

 DBCursor cur = collection.find();

 try{

   while(cur.hasNext()){

   DBObject doc = cur.next();

   System.out.println(doc);

  }

 }finally{

 cur.close();

 }

}

public static void count(DBCollection collection) {

 System.out.println("COunt of collection Documents : "+collection.count());

}

public static void findWithCriteriaUsingDBObject(DBCollection collection) {

 DBObject criteria = new BasicDBObject("type", "homework").append("student_id", 9);

 DBCursor cur = collection.find(criteria);

 try{

   while(cur.hasNext()){

   DBObject doc = cur.next();

   System.out.println(doc);

  }

 }finally{

  cur.close();

 }

}

public static void findWithCriteriaUsingQueryBuilder(DBCollection collection) {

 QueryBuilder builer =  QueryBuilder.start("type").is("homework").and("student_id").is(9).and("score").greaterThan(60);

 DBCursor cur = collection.find(builer.get(), new  BasicDBObject("student_id" , true).append("_id", false));

 try{

   while(cur.hasNext()){

   DBObject doc = cur.next();

   System.out.println(doc);

  }

 }finally{

  cur.close();

 }

}

}

Download the CODE from here.