BerkeleyDB-JE Hello World（使用BaseAPI）
在进一步介绍JE之前，我们先看个BaseAPI版的Hello World，这个例子演示了JE最一般的使用方法，打开环境和Database，持久化数据，查询数据，关闭环境和Database。

/** * 用BaseAPI保存和获取数据 * @author mengyang * */public class HelloWorldByBaseAPI {private File file = new File("C:/Users/mengyang/workspace/je");private Environment env;private Database database;//建立环境private void setUp(){EnvironmentConfig envConfig = new EnvironmentConfig();envConfig.setAllowCreate(true); env = new Environment(file, envConfig);DatabaseConfig dbConfig = new DatabaseConfig();dbConfig.setAllowCreate(true);database = env.openDatabase(null, "baseAPIDemo", dbConfig);}//保存数据private void save(){String key = "BaseAPI";String value = "Hello World!";try {DatabaseEntry keyEntry = new DatabaseEntry(key.getBytes("utf-8"));//键DatabaseEntry valueEntry = new DatabaseEntry(value.getBytes("utf-8"));//值database.put(null, keyEntry, valueEntry);//保存键值对} catch (UnsupportedEncodingException e) {e.printStackTrace();}}//检索数据private void get(){String key = "BaseAPI";String value;try {DatabaseEntry keyEntry = new DatabaseEntry(key.getBytes("utf-8"));//键DatabaseEntry valueEntry = new DatabaseEntry();//空的值if(database.get(null, keyEntry, valueEntry, LockMode.DEFAULT) == OperationStatus.SUCCESS){//根据键来查找value = new String(valueEntry.getData(), "utf-8");//找到了对于的值System.out.println("key:BaseAPI,value:"+value);}} catch (UnsupportedEncodingException e) {e.printStackTrace();}}//关闭环境private void shutDown(){database.close();env.close();}/** * @param args */public static void main(String[] args) {HelloWorldByBaseAPI myCase = new HelloWorldByBaseAPI();myCase.setUp();myCase.save();myCase.get();myCase.shutDown();}}