关于db4o 的工具类

关于对db40面向对象的数据库的操作工具类使用 

package com.example.test;import java.io.File;import android.content.Context;import android.os.Environment;import com.db4o.Db4oEmbedded;import com.db4o.ObjectContainer;public class DB4OUtils {//db4o数据库文件的位置 public static final String DB_PATH = "/SunLifeEverBright/Banca/advert.db4o";public static ObjectContainer instance = null;private DB4OUtils(){}public static ObjectContainer initDB4O() {ObjectContainer db = null;if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {try {String dbPath = Environment.getExternalStorageDirectory().toString() + DB_PATH;File file = new File(dbPath);if (!file.exists())file.createNewFile();db = Db4oEmbedded.openFile(Db4oEmbedded.newConfiguration(), dbPath);} catch (Exception e) {e.printStackTrace();}}return db;}/** * 得到ObjectContainer对象    单例来实现 * @return */public synchronized static ObjectContainer getInstance(){if (instance==null) {instance = initDB4O();}return instance;}/** * 关闭db链接 */public static void close(){if (instance!=null) {instance.close();}}}