使用db4o的QBE进行数据库的查询

使用db4o的QBE进行数据库的查询，使用的对象是Person，在上一篇文件中已经写过

import com.db4o.Db4oEmbedded;
import com.db4o.ObjectContainer;
import com.db4o.ObjectSet;
import com.db4o.eight.study.bean.Person;

public class DB4oQueryUseQBE {
	
	final static String DB4OFILENAME = System.getProperty("user.dir")
			+ "/database.db4o";

	public static void QBEQuery(){
		ObjectContainer db = Db4oEmbedded.openFile(
				Db4oEmbedded.newConfiguration(), DB4OFILENAME);
		Person proto = new Person(null, null, null);
		try {
			ObjectSet<Person> result = db.queryByExample(proto);
			System.out.println(result.size());
			for (Person per : result) {
			    System.out.println("id = " + per.getId()+
			    		", name = "+ per.getName() + ", password = " + per.getPassword());
			}
		} finally {
			db.close();
		}
	}
	
	public static void shortQBEQuery() {
		ObjectContainer db = Db4oEmbedded.openFile(
				Db4oEmbedded.newConfiguration(), DB4OFILENAME);
		try {
			ObjectSet<Person> result = db.queryByExample(Person.class);
			for (Person per : result) {
			    System.out.println("id = " + per.getId()+
			    		", name = "+ per.getName() + ", password = " + per.getPassword());
			}
		}
		finally {
			db.close();
		}
	}
	
	public static void queryByCondition() {
		ObjectContainer db = Db4oEmbedded.openFile(
				Db4oEmbedded.newConfiguration(), DB4OFILENAME);
		try {
			Person person = new Person("000002", null, "654321");
			ObjectSet<Person> result = db.queryByExample(person);
			for (Person per : result) {
			    System.out.println("id = " + per.getId()+
			    		", name = "+ per.getName() + ", password = " + per.getPassword());
			}
		}
		finally {
			db.close();
		}
	}
	
	public static void main(String[] args) {
//		DB4oQueryUseQBE.QBEQuery();
//		DB4oQueryUseQBE.shortQBEQuery();
		DB4oQueryUseQBE.queryByCondition();
	}
}