Java Db4oEmbedded类代码示例

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
public static void openDb4o(String repoPath) {

//        DB4OFILENAME = context.getRealPath("/WEB-INF/repository/ngsiRegRepo.db4o");
        DB4OFILENAME = repoPath;
        System.out.println(DB4OFILENAME);
        EmbeddedConfiguration configuration = Db4oEmbedded.newConfiguration();
        configuration.common().activationDepth(20); // set activation depth
        configuration.common().objectClass(RegisterContextRequest.class).cascadeOnDelete(true);
        db = Db4oEmbedded.openFile(configuration, DB4OFILENAME);        
    }
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
public static void openDb4o(String repoPath) {

//        DB4OFILENAME = context.getRealPath("/WEB-INF/repository/ngsiSubRepo.db4o");
        DB4OFILENAME = repoPath;
        System.out.println(DB4OFILENAME);
        EmbeddedConfiguration configuration = Db4oEmbedded.newConfiguration();
        configuration.common().activationDepth(15); // set activation depth
        configuration.common().objectClass(RegisterContextRequest.class).cascadeOnDelete(true);
        db = Db4oEmbedded.openFile(configuration, DB4OFILENAME);
    }
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
private ObjectContainer createConnection() {
    try {

        EmbeddedConfiguration config = Db4oEmbedded.newConfiguration();
        config.common().add(new TransparentPersistenceSupport());
        //Controls the number of objects in memory
        config.common().activationDepth(Integer.MAX_VALUE);
        //Controls the depth/level of updation of Object
        config.common().updateDepth(Integer.MAX_VALUE);

        //Register your top most Class here
        config.common().objectClass(CentralAuthority.class).cascadeOnUpdate(true); // Change to the object you want to save

        ObjectContainer db = Db4oEmbedded.openFile(config, FILENAME);
        return db;
    } catch (Exception ex) {
        System.out.print(ex.getMessage());
    }
    return null;
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
/**
	 * 配置db4o
	 * 
	 * @param 
	 * @return EmbeddedConfiguration
	 * @throws 
	 * 2013-8-28 下午02:23:56
	 */
	public EmbeddedConfiguration dbConfig() {
		EmbeddedConfiguration conf=Db4oEmbedded.newConfiguration();
		conf.common().objectClass(IDHolder.class).objectField("id").indexed(true);
//		Db4o.newConfiguration().blockSize(8);
//		conf.common().add(new TransparentActivationSupport());
//		conf.blockSize(int):这个可以配置Db4o文件的大小，参数范围为1-127,默认的是1,也就是默认的最大文件为2G,官方推荐的配置为8,正好是一个指针的长度，这样有利于加快速度
//		conf.activationDepth(int):这个是设置激活的深度，默认值是5,即当使用链表结构的时候最得首对象后最多只能往下走5层，这是为了不浪费内存
//		conf.lockDatabaseFile(true|false):默认值是true，即默认情况下是锁定数据库的，一个数据库文件只允许被一个应用程序读取，如果需要可以把它设为false，这样就能够允许多程序共享一个数据库了
//		conf.unicode(true|false):默认值是true，即默认是采用unicode编码的。采用unicode的好处是支持多国语言，不好的地方是速度变慢，如果没用中文或者为了速度起见，可以把它关闭
//		conf.weakReference(true|false):默认是true，即默认为持有一份对象的本地缓存，好处是使操作更快，缺点是一占内存，二如果要获得别人已经commit的对象要手动refresh一下
		return conf;
	}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
public void save(T obj) {
	if (obj == null) {
		return;
	}

	synchronized (DB4OUtils.class) {

		ObjectContainer oc = Db4oEmbedded.openFile(DB4OUtils
				.getDataBasePath());
		try {

			oc.store(obj);
			oc.commit();
			
		} catch (Exception e) {
			e.printStackTrace();
		} finally {

			oc.close();
		}
	}
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
@Override
public Collection<Integer> getKeys() throws StorageOperationException {
	ObjectContainer db = Db4oEmbedded.openFile(getConfiguration(), source);

	final Collection<Integer> result = new ArrayList<Integer>();

	try {
		db.query(new Predicate<V>() {
			@Override
			public boolean match(V v) {
				result.add(v.hashCode());
				return false;
			}
		});

	} finally {
		db.close();
	}

	return result;
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
@Override
public List<V> getAll(final K... keys) throws StorageOperationException {
	ObjectContainer db = Db4oEmbedded.openFile(getConfiguration(), source);

	List<V> result = null;
	try {
		result = db.query(new Predicate<V>() {
			@Override
			public boolean match(V v) {
				for (K key : keys) {
					if (key.match(v))
						return true;
				}
				return false;
			}
		});

	} finally {
		db.close();
	}
	if (result == null)
		return createList();
	else
		return result;
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
@Override
public void put(final K key, V value) throws StorageOperationException {
	ObjectContainer db = Db4oEmbedded.openFile(getConfiguration(), source);
	ObjectSet<V> set = db.query(new Predicate<V>() {
		@Override
		public boolean match(V v) {
			if (key.match(v))
				return true;
			else
				return false;
		}
	});
	db.delete(set);
	db.store(value);
	db.close();
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
/**
 * Configure the behavior of the database
 */

private EmbeddedConfiguration dbConfig() throws IOException {
	EmbeddedConfiguration configuration = Db4oEmbedded.newConfiguration();
	configuration.common().objectClass(Session.class).objectField("id")
			.indexed(true);
	configuration.common().objectClass(Contributor.class).objectField("id")
	.indexed(true);
	configuration.common().objectClass(Session.class).cascadeOnUpdate(true);
	configuration.common().objectClass(Speaker.class).objectField("email")
			.indexed(true);
	
	configuration.common().objectClass(Speaker.class).cascadeOnUpdate(true);
	return configuration;
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
private static void openDbFile() {
	db = Db4oEmbedded.openFile(Db4oEmbedded.newConfiguration(), DB_FOLDER + File.separator + DB_FILE_NAME);
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
public T get(final Object id) {

		T result = null;

		synchronized (DB4OUtils.class) {

			ObjectContainer oc = Db4oEmbedded.openFile(DB4OUtils
					.getDataBasePath());

			try {
				ObjectSet<T> os = oc.query(new Predicate<T>() {

					/**
				 * 
				 */
					private static final long serialVersionUID = 7212666772385276584L;

					@Override
					public boolean match(T t) {
						// TODO Auto-generated method stub
						return t.getId() != null && t.getId().equals(id);
					}
				});

				if (os.size() > 0) {
					result = os.get(0);
				}
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			} finally {

				oc.close();
			}
		}

		return result;
	}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
public void saveOrUpdateAll(Collection<T> col, final Match<T> match)
		throws Exception {
	if (col == null || col.size() == 0) {
		return;
	}

	synchronized (DB4OUtils.class) {

		ObjectContainer oc = Db4oEmbedded.openFile(DB4OUtils
				.getDataBasePath());

		try {
			for (final T obj : col) {

				ObjectSet<T> os = oc.query(new Predicate<T>() {

					/**
				 * 
				 */
					private static final long serialVersionUID = 2793555621552211152L;

					@Override
					public boolean match(T t) {
						// TODO Auto-generated method stub
						return match.match(t, obj);
					}
				});

				if (os.size() > 0) {
					T old = os.get(0);
					DB4OUtils.copyFields(obj, old);

					oc.store(old);

				} else {
					oc.store(obj);
				}
				
			}

			oc.commit();
		} catch (Exception e) {
			oc.rollback();
			throw e;

		} finally {

			oc.close();
		}

	}
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
public void saveOrUpdate(final T obj, final Match<T> match) {
	if (obj == null) {
		return;
	}

	synchronized (DB4OUtils.class) {

		ObjectContainer oc = Db4oEmbedded.openFile(DB4OUtils
				.getDataBasePath());
		try {

			ObjectSet<T> os = oc.query(new Predicate<T>() {

				/**
			 * 
			 */
				private static final long serialVersionUID = 2793555621552211152L;

				@Override
				public boolean match(T t) {
					// TODO Auto-generated method stub
					return match.match(t, obj);
				}
			});

			if (os.size() > 0) {
				T old = os.get(0);
				DB4OUtils.copyFields(obj, old);

				oc.store(old);

			} else {
				
				oc.store(obj);
			}
			
			oc.commit();

		} catch (Exception e) {
			e.printStackTrace();
		} finally {

			
			oc.close();
		}
	}
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
public static synchronized ObjectContainer getObjectContainer(Context context,String dbName){
	String DATABASE_PATH = context.getFilesDir().getAbsolutePath() + "/" + dbName;
	if (instance == null) {
		instance = Db4oEmbedded.openFile(DATABASE_PATH);
	}
	return instance;
}
 

import com.db4o.Db4oEmbedded; //导入依赖的package包/类
private static void openDbFile() {
    db = Db4oEmbedded.openFile(Db4oEmbedded.newConfiguration(), DB_FOLDER + File.separator + DB_FILE_NAME);
}