Google App Engine Java DataStore example

DatastoreSample.java

package info.narendran;

import java.io.IOException;

import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.KeyFactory;

@SuppressWarnings("serial")
public class DatastoreSample extends HttpServlet {
	public void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws IOException {
		resp.setContentType("text/plain");
		PersistenceManagerFactory PMF = JDOHelper
				.getPersistenceManagerFactory("transactions-optional");
		PersistenceManager pm = PMF.getPersistenceManager();
		if (req.getParameter("method").equals("put")) {

			Product product = new Product("1001", "jeans", 12.34);
			Product product1 = new Product("1002", "pants", 64.98);
			Key key = KeyFactory.createKey(Product.class.getSimpleName(),
					"1001");
			product.setKey(key);
			Key key1 = KeyFactory.createKey(Product.class.getSimpleName(),
					"1002");
			product1.setKey(key1);
			try {
				pm.makePersistent(product);
				pm.makePersistent(product1);
			} finally {
				pm.close();
			}
		} else if (req.getParameter("method").equals("get")) {
			Product e = pm.getObjectById(Product.class, req.getParameter("id"));
			resp.getWriter().println(
					"Product: " + e.getName() + ", Price: " + e.getPrice());
		}

	}
}

Product.java

package info.narendran;

import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

import com.google.appengine.api.datastore.Key;

@PersistenceCapable
public class Product {

	@PrimaryKey
	@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
	private Key key;

	@Persistent
	private String name;
	@Persistent
	private String id;
	@Persistent
	private double price;

	public Product(String id, String name, double price) {
		this.id = id;
		this.name = name;
		this.price = price;
	}

	public Key getKey() {
		return key;
	}

	public void setKey(Key key) {
		this.key = key;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public double getPrice() {
		return price;
	}

	public void setPrice(double price) {
		this.price = price;
	}
}