使用Berkeley DB (JE)存储key-value数据

/**
 * 封装对Berkeley DB一般操作的抽象类
 * **/
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;  
 
    public AbstractFrontier(String homeDirectory) throws DatabaseException, FileNotFoundException {  
        
        EnvironmentConfig envConfig = new EnvironmentConfig();  // 打开env  
        envConfig.setTransactional(true);  
        envConfig.setAllowCreate(true);  
        env = new Environment(new File(homeDirectory), envConfig);
         
        DatabaseConfig dbConfig = new DatabaseConfig();  // 设置DatabaseConfig
        dbConfig.setTransactional(true);
        dbConfig.setAllowCreate(true);
        
        catalogdatabase = env.openDatabase(null, CLASS_CATALOG, dbConfig);  // 打开  
        javaCatalog = new StoredClassCatalog(catalogdatabase);  

        database = env.openDatabase(null, "URL", dbConfig);  // 打开  
    }  
    
    //关闭数据库，关闭环境  
    public void close() throws DatabaseException {  
        database.close();  
        javaCatalog.close();  
        env.close();  
    }  
    //put方法  
    protected abstract void put(Object key,Object value);  
    //get方法  
    protected abstract Object get(Object key);  
    //delete方法  
    protected abstract Object delete(Object key);  
} 

public class BDBFrontier extends AbstractFrontier {  
    @SuppressWarnings("unchecked")
	private StoredMap pendingUrisDB = null;
 
    //使用默认的路径和缓存大小构造函数
	public BDBFrontier(String homeDirectory) throws DatabaseException, FileNotFoundException{  
        super(homeDirectory);
        EntryBinding<String> keyBinding = new SerialBinding<String>(javaCatalog, String.class);
        EntryBinding<String> valueBinding = new SerialBinding<String>(javaCatalog, String.class);
        pendingUrisDB = new StoredMap<String, String>(database, keyBinding, valueBinding, true);
    }  
	
    // 底层存入数据库
	@SuppressWarnings("unchecked")
	public void put(Object key, Object value) {  
        pendingUrisDB.put(key, value);
    }
    //取出
    public Object get(Object key){
        return pendingUrisDB.get(key);
    }
    //删除  
    public Object delete(Object key){  
        return pendingUrisDB.remove(key);  
    }
    
    //是否包含key
    public boolean containKey(Object key){
    	return pendingUrisDB.containsKey(key);
    }
    
    //得到keySet
    @SuppressWarnings("unchecked")
	public Set<String> getKeySet(){
    	return pendingUrisDB.keySet();
    }
    
    // 测试函数
    public static void main(String[] strs) throws Exception {
    	BDBFrontier  bDBFrontier = new BDBFrontier("E:\\BerkeleyDB");

    	for (int i = 0; i < 30; i++) {
    		bDBFrontier.put("www" + i, "http://" + i);
		}
    	
    	Set<String> set = bDBFrontier.getKeySet();
    	for (String Str : set) {
    		System.out.println(Str);
		}
    	bDBFrontier.close();
    }
}