JpqlShellUtility.java

package blerg;

import static org.apache.commons.lang.StringUtils.*;

import java.util.List;
import java.util.Scanner;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

@Transactional
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "/appContext.xml" })
public class JpqlShellUtility {
	
	@PersistenceContext private EntityManager em;

	@Test
	public void executeShell() {
		Scanner scanner = new Scanner(System.in);
		String query;
		do {		
			System.out.print("> ");
			query = scanner.nextLine();			
			try {
				System.out.print(performQuery(query));
			} catch(Exception e) {
				e.printStackTrace();
			}
		} while(!trim(query).equals("quit"));
	}

	@SuppressWarnings("unchecked")
	private String performQuery(String jpql) {
		if(isBlank(jpql)) return "";

		Query query = em.createQuery(jpql).setMaxResults(10);
		List<Object> results = query.getResultList();

		StringBuilder sb = new StringBuilder();
		sb.append("Found ").append(results.size()).append(" records.\n");
		for (Object object : results) {			
			sb.append(ToStringBuilder.reflectionToString(object)).append("\n");
		}		
		return sb.toString();
	}	
}