一个简单关于Berkeley DB的读写问题

import java.io.*;
import com.sleepycat.je.*;
import com.sleepycat.bind.tuple.*;
public class BD {

	/**
	 * @param args
	 */
	

	public void writer() {

		try {
			// 配置环境
			EnvironmentConfig envConfig = new EnvironmentConfig();
			// 设置配置事务
			envConfig.setTransactional(true);
			// 如果不存在就创建环境
			envConfig.setAllowCreate(true);
			File file = new File("E:/BDB/");
			file.mkdirs();
			// 创建数据库环??
			Environment exampleEnv = new Environment(file, envConfig);
			// ??始数据库环境事务
			Transaction txn = exampleEnv.beginTransaction(null, null);
			// 数据库配??
			DatabaseConfig dbConfig = new DatabaseConfig();
			// ??始数据库配置事务
			dbConfig.setTransactional(true);
			// 如果没有数据库配置那么创??
			dbConfig.setAllowCreate(true);
			// 数据库设置一个key是否允许存储多个值，true代表允许，默认false.

			dbConfig.setSortedDuplicates(false);
			// 打开??个数据库
			Database exampleDb = exampleEnv.openDatabase(txn, "simpleDb",
					dbConfig);
			txn.commit();

			DatabaseEntry keyEntry = new DatabaseEntry();
			DatabaseEntry dataEntry = new DatabaseEntry();

			/* put some data in */

			txn = exampleEnv.beginTransaction(null, null);
			// 存入key，value
			StringBinding.stringToEntry("主键", keyEntry);
			StringBinding.stringToEntry("值", dataEntry);
			OperationStatus status = exampleDb.put(txn, keyEntry, dataEntry);

			if (status != OperationStatus.SUCCESS) {
				throw new DatabaseException("Data insertion got status "
						+ status);
			}
			// 同步
			txn.commitNoSync();
			// 关闭数据??
			exampleDb.close();
			// 关闭环境
			exampleEnv.close();
		} catch (DatabaseException e) {

			e.printStackTrace();
		}

	}
	
public void read(){
		
		try {	//配置环境
			EnvironmentConfig envConfig = new EnvironmentConfig();
			//设置配置事务
	        envConfig.setTransactional(true); 
	        envConfig.setAllowCreate(true);    
	        Environment exampleEnv = new Environment(new File("E:/BDB"), envConfig);

	        Transaction txn = exampleEnv.beginTransaction(null, null);
	        DatabaseConfig dbConfig = new DatabaseConfig();
	        dbConfig.setTransactional(true); 
	        dbConfig.setAllowCreate(true);
	        dbConfig.setSortedDuplicates(false);
	        Database exampleDb = exampleEnv.openDatabase(txn, 
	                                                     "simpleDb",
	                                                     dbConfig);
	        txn.commit();

	        DatabaseEntry keyEntry = new DatabaseEntry();
	        DatabaseEntry dataEntry = new DatabaseEntry();
           
	        

            /* retrieve the data */
            txn = exampleEnv.beginTransaction(null, null);
            //打开游标
            Cursor cursor = exampleDb.openCursor(txn, null);

            while (cursor.getNext(keyEntry, dataEntry, LockMode.DEFAULT) ==
                   OperationStatus.SUCCESS) {
                System.out.println("key=" + 
                				  //实体转字符串
                		 StringBinding.entryToString(keyEntry) +
                                   " data=" + 
                                   StringBinding.entryToString(dataEntry));
               
            }
            
            cursor.close();
            txn.commitNoSync();
            exampleDb.close();
            exampleEnv.close();
	        
	        
	        
			} catch (DatabaseException e) {
				
				e.printStackTrace();
			}
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		BD myDB=new BD();
		myDB.writer();
		myDB.read();
		

	}

}