一个简单的NoSQL内存数据库—Berkeley DB基本操作的例子

package webspider.berkeleydb;

import java.io.Serializable;

/**
 * 定义一个序列化的java类，放到Berkeley DB中
 * 
 * @author typ
 * 
 */
public class Bean implements Serializable {
	private static final long serialVersionUID = -6865837107626208563L;

	private Integer id;
	private String name;

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

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

}

package webspider.berkeleydb;

/**
 * 定义需要实现的功能接口
 * 
 * @author typ
 * 
 */
public interface Frontier {
	/**
	 * 获得下一条记录
	 * 
	 * @return
	 * @throws Exception
	 */
	public Bean getNext() throws Exception;

	/**
	 * 添加一条记录
	 * 
	 * @param bean
	 * @return
	 * @throws Exception
	 */
	public boolean putNext(Bean bean) throws Exception;

}

package webspider.berkeleydb;

import java.io.File;
import com.sleepycat.bind.serial.StoredClassCatalog;
import com.sleepycat.je.Database;
import com.sleepycat.je.DatabaseConfig;
import com.sleepycat.je.Environment;
import com.sleepycat.je.EnvironmentConfig;

/**
 * 封装Berkeley DB的操作
 * 
 * @author typ
 * 
 */
public abstract class AbstractFrontier {

	private Environment env;
	private static final String CLASS_CATALOG = "java_class_catalog";
	protected StoredClassCatalog javaCatalog;
	protected Database catalogDatabase;
	protected Database database;

	/**
	 * 初始化数据库需要的各种变量
	 * 
	 * @param homeDirectory
	 * @throws Exception
	 */
	public AbstractFrontier(String homeDirectory) throws Exception {
		EnvironmentConfig envConfig = new EnvironmentConfig();
		// 设置事务处理开启，
		envConfig.setTransactional(true);
		// AllowCreate属性表示没有数据库的前提下，可以自动创建数据库
		envConfig.setAllowCreate(true);
		// 定义Environment变量，homeDirectory指的是数据库存放路径
		env = new Environment(new File(homeDirectory), envConfig);
		// 设置数据库的属性
		DatabaseConfig dbConfig = new DatabaseConfig();
		dbConfig.setTransactional(true);
		dbConfig.setAllowCreate(true);
		// 通常java对象和java对象之间的映射关系要分开存放，放置到不同的数据库中
		// 存放java对象的数据库
		catalogDatabase = env.openDatabase(null, CLASS_CATALOG, dbConfig);
		javaCatalog = new StoredClassCatalog(catalogDatabase);
		// 存放key/value映射的数据库<String,JavaBean>
		database = env.openDatabase(null, "String_JavaBean", dbConfig);
	}

	/**
	 * 关闭数据库时候，关闭各种链接
	 * 
	 * @throws Exception
	 */
	public void close() throws Exception {
		database.close();
		javaCatalog.close();
		env.close();
	}

	/**
	 * Berkeley DB的存储键值对操作
	 * 
	 * @param key
	 * @param value
	 */
	protected abstract void put(Object key, Object value);

	/**
	 * Berkeley DB的得到键值对操作
	 * 
	 * @param key
	 * @return
	 */
	protected abstract Object get(Object key);

	/**
	 * Berkeley DB的删除键值对操作
	 * 
	 * @param key
	 * @return
	 */
	protected abstract Object delete(Object key);
}

package webspider.berkeleydb;

import java.util.Map.Entry;
import java.util.Set;
import com.sleepycat.bind.EntryBinding;
import com.sleepycat.bind.serial.SerialBinding;
import com.sleepycat.collections.StoredMap;

/**
 * 具体实现类
 * 
 * @author typ
 * 
 */
public class BDBFrontier extends AbstractFrontier implements Frontier {
	// 建立map，存储key/value键值对
	private StoredMap pendingUrisDBMap;

	/**
	 * 初始化java对象数据库和对象映射数据库
	 * 
	 * @param homeDirectory
	 * @throws Exception
	 */
	public BDBFrontier(String homeDirectory) throws Exception {
		super(homeDirectory);
		// 定义key和value的Entry
		EntryBinding keyBinding = new SerialBinding(javaCatalog, String.class);
		EntryBinding valueBinding = new SerialBinding(javaCatalog, Bean.class);
		// map存放在database中，database存放key/value映射
		pendingUrisDBMap = new StoredMap(database, keyBinding, valueBinding,
				true);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see webspider.berkeleydb.Frontier#getNext()
	 */
	public Bean getNext() throws Exception {
		Bean bean = null;
		if (!pendingUrisDBMap.isEmpty()) {
			Set<Entry<String, Bean>> entrys = pendingUrisDBMap.entrySet();
			Entry<String, Bean> entry = (Entry<String, Bean>) pendingUrisDBMap
					.entrySet().iterator().next();
			bean = entry.getValue();
			delete(entry.getKey());
		}
		return bean;
	}

	/* (non-Javadoc)
	 * @see webspider.berkeleydb.Frontier#putNext(webspider.berkeleydb.Bean)
	 */
	public boolean putNext(Bean bean) throws Exception {
		put(bean.getName(), bean);
		return true;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see webspider.berkeleydb.AbstractFrontier#put(java.lang.Object,
	 * java.lang.Object)
	 */
	protected void put(Object key, Object value) {
		pendingUrisDBMap.put(key, value);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see webspider.berkeleydb.AbstractFrontier#get(java.lang.Object)
	 */
	protected Object get(Object key) {
		return pendingUrisDBMap.get(key);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see webspider.berkeleydb.AbstractFrontier#delete(java.lang.Object)
	 */
	protected Object delete(Object key) {
		return pendingUrisDBMap.remove(key);
	}

	/**
	 * 测试效果，可以看到在f:\bdb文件夹下面生成了.jdb和.lck等Berkeley DB相关文件，数据存储在.jdb中
	 * 控制台输出刚刚插入的数据bean的Name值LiMing
	 */
	public static void main(String[] args) {
		try {
			BDBFrontier frontier = new BDBFrontier("f:\\bdb");
			Bean bean = new Bean();
			bean.setName("LiMing");
			frontier.putNext(bean);
			System.out.println(frontier.getNext().getName());
			frontier.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}