前不久也封装了一个，但那个是基于存储映射实现的，因为要实现特定对象存储，所以过程有些复杂，今天是直接使用BerkeleyDB的API封装成的一个MyBerkeleyDB，简单易用。下面上代码：
步骤1、确定类和变量/********************************* * 使用BerkeleyDB封装了一些数据库操作 * 包括设置缓冲区，设置编码，设置数据可库 * 路径，存储键值对，，根据键查找值，关闭数 * 据库等操作。 * @author Administrator *********************************/{(“unused”)chacheSize;//缓冲区大小}2、实现构造函数和一些参数的修改器 public MyBerkeleyDB(){charset = “utf-8″;//编码默认使用UTF-8chacheSize = 10000;//缓冲区大小默认为10000}(String charset){this.charset = charset;}(String path){//判断Path是否存在File file = new File(path);if(file.mkdir()){System.out.println(path+”已创建！”); //不存在则创建一个}else{System.out.println(path+”已存在！”); //存在则说明已存在}//确定存储路径this.path = path;}//设置缓冲区大小public boolean setChacheSize(long size){if(size<=0 || size >=1000000000){return false; //使用默认的大小}this.chacheSize = size;return true;}3、创建环境 (String path , long chacheSize){setPath(path);setChacheSize(chacheSize);//配置环境EnvironmentConfig envConfig = new EnvironmentConfig();envConfig.setAllowCreate(true);envConfig.setCacheSize(this.chacheSize);//创建环境environment = new Environment(new File(this.path),envConfig);}4、打开数据库名为dbName的数据库和关闭的方法 (String dbName){DatabaseConfig dbConfig = new DatabaseConfig();dbConfig.setAllowCreate(true);dbConfig.setSortedDuplicates(false); //不存储重复关键字this.database = environment.openDatabase(null, dbName, dbConfig);}(){database.close();environment.close();}5、put、get、del、size方法的实现 (Object key,Object value){DatabaseEntry k = new DatabaseEntry(toByteArray(key));DatabaseEntry v = new DatabaseEntry(toByteArray(value));database.put(null, k, v);}//取值public Object get(Object key){DatabaseEntry k = new DatabaseEntry(toByteArray(key));DatabaseEntry v = new DatabaseEntry();database.get(null, k, v, LockMode.DEFAULT);if(v == null){return null;}return toObject(v.getData());}//按照键值删除数据public Object del(Object key){DatabaseEntry k = new DatabaseEntry(toByteArray(key)); //键值转化Object value = get(key);//获取值database.removeSequence(;//返回删除的值}(){return database.count();}6、遍历数据库，包括获取所有的键值和获取所有键值对 // 获取数据库所有的key键public ArrayList<Object> getAllKey(){ArrayList<Object> result = new ArrayList<Object>();Cursor cursor = database.openCursor(null, null);DatabaseEntry key = new DatabaseEntry();DatabaseEntry value = new DatabaseEntry();while(cursor.getNext(key, value, LockMode.DEFAULT) ==OperationStatus.SUCCESS){Object k = toObject(key.getData());if(k != null){result.add(k);key = new DatabaseEntry();}else{key = new DatabaseEntry();}}cursor.close();return result;}//遍历数据库public ArrayList<Entry<Object,Object>> getAllItems(){Cursor cursor = null;//游标ArrayList<Entry<Object,Object>> result = new ArrayList<Entry<Object,Object>>();cursor = database.openCursor(null, null);DatabaseEntry theKey = new DatabaseEntry();DatabaseEntry theValue = new DatabaseEntry();//使用Cursor方法来遍历游标获取数据if(cursor.getFirst(theKey, theValue, LockMode.DEFAULT)== OperationStatus.SUCCESS){Object key = toObject(theKey.getData());Object value = toByteArray(theValue.getData());Entry<Object,Object> entry = new SimpleEntry<Object,Object>(key,value);result.add(entry);while(cursor.getNext(theKey, theValue, LockMode.DEFAULT)== OperationStatus.SUCCESS){//System.out.println(new String(theKey.getData()));key = theKey.getData();value = theValue.getData();entry = new SimpleEntry<Object,Object>(key,value);result.add(entry);}}cursor.close();//关闭游标return result;}7、两个工具函数：Object转为Byte[]，Byte[]转为Object[] toByteArray (Object obj) {if(obj == null)return null;byte[] bytes = null;ByteArrayOutputStream bos = new ByteArrayOutputStream();try {ObjectOutputStream oos = new ObjectOutputStream(bos);oos.writeObject(obj);oos.flush();bytes = bos.toByteArray ();oos.close();bos.close();} catch (IOException ex) {//ex.printStackTrace(); }return bytes;}Object toObject (byte[] bytes){if(bytes == null)return null;Object obj = null;try {ByteArrayInputStream bis = new ByteArrayInputStream (bytes);ObjectInputStream ois = new ObjectInputStream (bis);obj = ois.readObject();ois.close();bis.close();} catch (IOException ex) {//ex.printStackTrace(); } catch (ClassNotFoundException ex) {//ex.printStackTrace(); }return obj;} 8、main测试函数(String[] args) throws Exception {MyBerkeleyDB db = new MyBerkeleyDB();db.setEnvironment(“C:\\BerkeleyDB\\MyDatabase2”, 1000000);db.open((int i=10; i>=0; i–) {String key = “Key”+i;Integer value = i;db.put(key , value);System.out.println(“[” + key + “:” + db.get(key) + “]”);}//获取数据库键值对数量System.out.println(db.size());//删除数据测试System.out.println(“删除：”+db.del(“Key3″));//测试获取所有键值ArrayList<Object> set = db.getAllKey();System.out.println(set.size());Iterator<Object> it = set.iterator();while(it.hasNext()){String s = it.next().toString();System.out.println(s+”:”+db.get(s));}//测试遍历数据库ArrayList<Entry<Object,Object>> r = db.getAllItems();for(int i = 0; i < r.size();i++){Object key = r.get(i).getKey();Object value = r.get(i).getValue();if(key != null && value != null)System.out.println(key.toString()+”-“+(String)value);}db.close();}
空虚无聊的时候就读书，但一定得有自己的生活目标和计划。
