Berkely DB Java Edition学习札记

Berkely DB Java Edition学习笔记

Berkely DB对于高并发、要求速度快的应用来说是个不错的选择，mysql就是用BDB实现的(mysql的后台) ，mysql快，BDB比mysql还要快N倍。BDB是一种嵌入式的、非关系数据库，它与其他的关系数据库RMDBS不同,它没有提供SQL,而是提供了自己的访问接口。作为一种嵌入式的数据库，它是进程内模式的，也就是说它和应用程序在同一内存空间运行，所以速度要高很多，与嵌入式的数据库如Derby、HSQLDB(都是RMDBS的)相比，它效率更高，使用方法也有很大的不同。现在BDB以被Oracle收购。Berkely DB提供的文档Getting Started with　Berkeley DB Java Edition可以说是短小精悍（１１３页），入门相当不错。下面Get Start吧：
Environment：
首先要接触的就是Environment了，使用它来open　database以及做一管理方面的事情.
创建Environment，还需要Environment的一些配置信息EnvironmentConfig。
下面是创建的过程：

EnvironmentConfig envConfig = new EnvironmentConfig();
envConfig.setAllowCreate(true);
myDbEnvironment = new Environment(new File("/export/dbEnv"),
envConfig);

其中EnvironmentConfig提供了许多配置参数，常用的有：
envConfig.setAllowCreate()//如果不存在的env的话，是否要创建一个新的
envConfig.setReadOnly()//是否为只读的
envConfig.setTransactional()//是否使用事务
参数都是boolean类型的
除了EnvironmentConfig外，还有EnvironmentMutableConfig，他实际是EnvironmentConfig的父类，使用他来配置在创建完Environment之后可以改变
的属性：
setCachePercent()//设置cache的大小占JVM　memory的百分比
setCacheSize()//设置cache的大小
setTxnNoSync()//事务提交是否将改变的记录写入磁盘
setTxnWriteNoSync()//事务提交是否将log写入磁盘
下面看一下使用EnvironmentMutableConfig的方法:

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Environment myEnv = new Environment(new File("/export/dbEnv"), null);??
EnvironmentMutableConfig envMutableConfig =??
new EnvironmentMutableConfig();??
envMutableConfig.setTxnNoSync(true);??
myEnv.setMutableConfig(envMutableConfig);?

Environment myEnv = new Environment(new File("/export/dbEnv"), null);
EnvironmentMutableConfig envMutableConfig =
new EnvironmentMutableConfig();
envMutableConfig.setTxnNoSync(true);
myEnv.setMutableConfig(envMutableConfig);

Environment通过close来关闭，释放资源
下面看看Environment在管理方面的一些方法：
可以通过Environment获得EnvironmentStats，他提供了Environment一些状态信息，
例如使用

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long cacheMisses = myEnv.getStats(null).getNCacheMiss();?

long cacheMisses = myEnv.getStats(null).getNCacheMiss();

我们可以获得cache未命中的次数，据此来调整cache的大小
可以同过Environment.getDatabaseNames()来获得Environment的数据库的名字：

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List myDbNames = myDbEnv.getDatabaseNames();??
for(int i=0; i < myDbNames.size(); i++) {??
System.out.println("Database Name: " + (String)myDbNames.get(i));??
}?

List myDbNames = myDbEnv.getDatabaseNames();
for(int i=0; i < myDbNames.size(); i++) {
System.out.println("Database Name: " + (String)myDbNames.get(i));
}

可以通过Environment.removeDatabase()来删除一个数据库：

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String dbName = myDB.getDatabaseName();??
myDB.close();??
myDBEnv.removeDatabase(null,dbName);?

String dbName = myDB.getDatabaseName();
myDB.close();
myDBEnv.removeDatabase(null,dbName);

可以使用Environment.renameDatabase()来重新命名一个数据库：

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String dbName = myDB.getDatabaseName();??
String dbNewName = new String(dbName + ".new", "UTF-8");??
myDB.close();??
myDBEnv.renameDatabase(null,dbName,dbNewName);?

String dbName = myDB.getDatabaseName();
String dbNewName = new String(dbName + ".new", "UTF-8");
myDB.close();
myDBEnv.renameDatabase(null,dbName,dbNewName);

可以使用Environment.truncateDatabase()来删除数据库中的所有记录：

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myEnv.truncate(null, // txn handle??
myDatabase.getDatabaseName(), // database name??
true//whether to return the count of deleted records??
);?

myEnv.truncate(null, // txn handle
myDatabase.getDatabaseName(), // database name
true//whether to return the count of deleted records
);

第三个参数是否返回删除的记录数，性能有很大不同。false的话会很快
Database:
最重要的一些操作大多都在Database里了，和Environment一样，它也有许多
配置的选项DatabaseConfig,我们先看看选项：
DatabaseConfig.setAllowCreate()//不能存在的话是open操作否创建新的
DatabaseConfig.setBtreeComparator()//设置Btree的比较器
DatabaseConfig.setDuplicateComparator()//设置判断重复的比较器
DatabaseConfig.setSortedDuplicates()//是否允许重复的记录
DatabaseConfig.setExclusiveCreate()//设为true,如果当前数据库已存在，则open失败，也就是说open操作会导致一个新的数据库被创建，默认为false
DatabaseConfig.setReadOnly()//是否是只读的
DatabaseConfig.setTransactional()//是否使用事务
下面我们看看Database的使用流程：

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EnvironmentConfig envConfig = new EnvironmentConfig();??
envConfig.setAllowCreate(true);??
myDbEnvironment = new Environment(new File("/export/dbEnv"), envConfig);??
DatabaseConfig dbConfig = new DatabaseConfig();??
dbConfig.setAllowCreate(true);??
myDatabase = myDbEnvironment.openDatabase(null,??
"sampleDatabase",??
dbConfig);?

EnvironmentConfig envConfig = new EnvironmentConfig();
envConfig.setAllowCreate(true);
myDbEnvironment = new Environment(new File("/export/dbEnv"), envConfig);
DatabaseConfig dbConfig = new DatabaseConfig();
dbConfig.setAllowCreate(true);
myDatabase = myDbEnvironment.openDatabase(null,
"sampleDatabase",
dbConfig);

我们通过Environment的openDatabase来创—atabase对象。使用完了Database使用
close方法来关闭数据库释放资源。
Database Records
Database Record是保存在数据库的内容，包含Key和value两部分，他们都被封装成
DatabaseEntry，DatabaseEntry只能存放字节数组，所以只要能把Key和Value是什么
类型的，只要能转化成字节数组就可以被DatabaseEntry封装。基本类型JE都有对应的Binding,复杂的类型可以使用序列化和自定义binding来实现。
下那面我们看看一个使用方法：

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String aKey = "key";??
String aData = "data";??
try {??
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));??
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));??
} catch (Exception e) {??
}?

String aKey = "key";
String aData = "data";
try {
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));
} catch (Exception e) {
}

我们不应该依赖机器默认的编码，通常要指定特定的编码方法getBytes("UTF-8");
我们先看看怎么从数据库中读写记录：
通过Database.put()和Database.get()我们可以从数据库中读写记录
put:

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String aKey = "myFirstKey";??
String aData = "myFirstData";??
try {??
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));??
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));??
myDatabase.put(null, theKey, theData);??
} catch (Exception e) {??
}?

String aKey = "myFirstKey";
String aData = "myFirstData";
try {
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));
myDatabase.put(null, theKey, theData);
} catch (Exception e) {
}

get:

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String aKey = "myFirstKey";??
try {??
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));??
DatabaseEntry theData = new DatabaseEntry();??
?
if (myDatabase.get(null, theKey, theData, LockMode.DEFAULT) ==??
OperationStatus.SUCCESS) {??
?
byte[] retData = theData.getData();??
String foundData = new String(retData, "UTF-8");??
System.out.println("For key: '" + aKey + "' found data: '" +??
foundData + "'.");??
} else {??
? System.out.println("No record found for key '" + aKey + "'.");??
}??
} catch (Exception e) {??
}?

String aKey = "myFirstKey";
try {
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
DatabaseEntry theData = new DatabaseEntry();

if (myDatabase.get(null, theKey, theData, LockMode.DEFAULT) ==
OperationStatus.SUCCESS) {

byte[] retData = theData.getData();
String foundData = new String(retData, "UTF-8");
System.out.println("For key: '" + aKey + "' found data: '" +
foundData + "'.");
} else {
? System.out.println("No record found for key '" + aKey + "'.");
}
} catch (Exception e) {
}

删除操作:

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String aKey = "myFirstKey";??
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));??
myDatabase.delete(null, theKey);?

String aKey = "myFirstKey";
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
myDatabase.delete(null, theKey);

使用BIND APIs来操作基本类型：
我们可以使用JE提供的Bind Apis来操作数字类型和字符串类型：
以Long为例：
存储数据使用Bind Apis一般步骤如下：
1、通过EntryBinding binding =TupleBinding.getPrimitiveBinding(Long.class);
2、通过EntryBinding 把数据放到DatabaseEntry中：
myBinding.objectToEntry(data, dataEntry);
获取数据使用Bind Apis一般步骤如下：
1、通过EntryBinding binding =TupleBinding.getPrimitiveBinding(Long.class);
2、通过EntryBinding将Entry转换成Object Long theLong = (Long) myBinding.entryToObject(theData);
下面代码以测试的形式演示了整个过程：

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package edu.jlu.fuliang;??
?
import java.io.File;??
?
import com.sleepycat.bind.EntryBinding;??
import com.sleepycat.bind.tuple.TupleBinding;??
import com.sleepycat.je.Database;??
import com.sleepycat.je.DatabaseConfig;??
import com.sleepycat.je.DatabaseEntry;??
import com.sleepycat.je.Environment;??
import com.sleepycat.je.EnvironmentConfig;??
import com.sleepycat.je.LockMode;??
?
import junit.framework.TestCase;??
?
public class PrimitiveBindingTest extends TestCase{??
??? private Environment env;??
??? private Database db;??
??? private String key = "akey";??
??? private Long data = 1234556633L;??
??????
??? public void setUp()throws Exception{??
??????? EnvironmentConfig envConfig = new EnvironmentConfig();??
??????? envConfig.setAllowCreate(true);??
??????? env = new Environment(new File("etc/dbEnv"),envConfig);??
??????? DatabaseConfig dbConfig = new DatabaseConfig();??
??????? dbConfig.setAllowCreate(true);??
??????? db = env.openDatabase(null, "myDB", dbConfig);??
??????? DatabaseEntry keyEntry = new DatabaseEntry(key.getBytes("UTF-8"));??
??????? DatabaseEntry dataEntry = new DatabaseEntry();??
??????????
??????? EntryBinding myBinding = TupleBinding.getPrimitiveBinding(Long.class);??
??????? myBinding.objectToEntry(data, dataEntry);??
??????? db.put(null, keyEntry, dataEntry);??
??? }??
??????
??? public void testGet()throws Exception{??
??????? DatabaseEntry keyEntry = new DatabaseEntry(key.getBytes("UTF-8"));??
??????? DatabaseEntry dataEntry = new DatabaseEntry();??
??????? EntryBinding binding = TupleBinding.getPrimitiveBinding(Long.class);??
??????? db.get(null, keyEntry, dataEntry, LockMode.DEFAULT);??
??????? Long l = (Long)binding.entryToObject(dataEntry);??
??????? assertEquals(l,data);??
??? }??
??? public void tearDown()throws Exception{??
??????? db.close();??
??????? env.truncateDatabase(null, "myDB",false);??
??????? env.close();??
??? }??
??????
}?

package edu.jlu.fuliang;

import java.io.File;

import com.sleepycat.bind.EntryBinding;
import com.sleepycat.bind.tuple.TupleBinding;
import com.sleepycat.je.Database;
import com.sleepycat.je.DatabaseConfig;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.Environment;
import com.sleepycat.je.EnvironmentConfig;
import com.sleepycat.je.LockMode;

import junit.framework.TestCase;

public class PrimitiveBindingTest extends TestCase{
?private Environment env;
?private Database db;
?private String key = "akey";
?private Long data = 1234556633L;
?
?public void setUp()throws Exception{
??EnvironmentConfig envConfig = new EnvironmentConfig();
??envConfig.setAllowCreate(true);
??env = new Environment(new File("etc/dbEnv"),envConfig);
??DatabaseConfig dbConfig = new DatabaseConfig();
??dbConfig.setAllowCreate(true);
??db = env.openDatabase(null, "myDB", dbConfig);
??DatabaseEntry keyEntry = new DatabaseEntry(key.getBytes("UTF-8"));
??DatabaseEntry dataEntry = new DatabaseEntry();
??
??EntryBinding myBinding = TupleBinding.getPrimitiveBinding(Long.class);
???? myBinding.objectToEntry(data, dataEntry);
???? db.put(null, keyEntry, dataEntry);
?}
?
?public void testGet()throws Exception{
??DatabaseEntry keyEntry = new DatabaseEntry(key.getBytes("UTF-8"));
??DatabaseEntry dataEntry = new DatabaseEntry();
??EntryBinding binding = TupleBinding.getPrimitiveBinding(Long.class);
??db.get(null, keyEntry, dataEntry, LockMode.DEFAULT);
??Long l = (Long)binding.entryToObject(dataEntry);
??assertEquals(l,data);
?}
?public void tearDown()throws Exception{
??db.close();
??env.truncateDatabase(null, "myDB",false);
??env.close();
?}
?
}

序列化复杂的类型
步骤如下：
1、要存储的对象的类需要实现java.io.Serializable
2、打开两个数据库，一个存放数据，另一个存放类的信息
3、实例化com.sleepycat.bind.serial.StoredClassCatalog对象
4、创建uses com.sleepycat.bind.serial.SerialBinding对象
5、使用SerialBinding把对象放到DatabaseEntry中
下面是使用一个能够完整描述这个过程的例子来说明这个过程：

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package edu.jlu.fuliang;??
?
import java.io.File;??
?
import com.sleepycat.bind.EntryBinding;??
import com.sleepycat.bind.serial.SerialBinding;??
import com.sleepycat.bind.serial.StoredClassCatalog;??
import com.sleepycat.je.Database;??
import com.sleepycat.je.DatabaseConfig;??
import com.sleepycat.je.DatabaseEntry;??
import com.sleepycat.je.DatabaseException;??
import com.sleepycat.je.Environment;??
import com.sleepycat.je.EnvironmentConfig;??
import com.sleepycat.je.LockMode;??
?
import junit.framework.TestCase;??
?
public class SerializableTypeTest extends TestCase{??
??? private Person person;??
??? private Environment env;??
??? private Database db,classDB;??
??? private StoredClassCatalog classCatalog;??
??????
??? public void setUp()throws Exception{??
??????? person = new Person();??
??????? person.setAge(12);??
??????? person.setName("zhansan");??
??????? person.setSex('m');??
??????????
??????? EnvironmentConfig envConfig = new EnvironmentConfig();??
??????? envConfig.setAllowCreate(true);??
??????? env = new Environment(new File("etc/dbEnv"),envConfig);??
??????? DatabaseConfig dbConfig = new DatabaseConfig();??
??????? dbConfig.setAllowCreate(true);??
??????? db = env.openDatabase(null, "myDB", dbConfig);??
??????? classDB = env.openDatabase(null, "classDB", dbConfig);??
??????? classCatalog = new StoredClassCatalog(classDB);??
??????? EntryBinding dataBinding = new SerialBinding(classCatalog,Person.class);??
??????????????
??????? DatabaseEntry keyEntry = new DatabaseEntry(person.getName().getBytes("UTF-8"));??
??????? DatabaseEntry dataEntry = new DatabaseEntry();??
??????? dataBinding.objectToEntry(person, dataEntry);??
??????? db.put(null, keyEntry, dataEntry);??
??? }??
??????
??? public void testGet()throws Exception{??
??????? EntryBinding dataBinding = new SerialBinding(classCatalog,Person.class);??
????????
??????? DatabaseEntry keyEntry = new DatabaseEntry(person.getName().getBytes("UTF-8"));??
??????? DatabaseEntry dataEntry = new DatabaseEntry();??
??????? db.get(null, keyEntry, dataEntry, LockMode.DEFAULT);??
??????? Person p = (Person)dataBinding.entryToObject(dataEntry);??
??????? assertEquals(p.getName(),person.getName());??
??????? assertEquals(p.getAge(),person.getAge());??
??????? assertEquals(p.getSex(), person.getSex());??
??? }??
??????
??? public void tearDown()throws Exception{??
??????? db.close();??
??????? classDB.close();??
??????? env.truncateDatabase(null, "myDB", false);??
??????? env.truncateDatabase(null, "classDB", false);??
??????? env.close();??
??? }??
}?

package edu.jlu.fuliang;

import java.io.File;

import com.sleepycat.bind.EntryBinding;
import com.sleepycat.bind.serial.SerialBinding;
import com.sleepycat.bind.serial.StoredClassCatalog;
import com.sleepycat.je.Database;
import com.sleepycat.je.DatabaseConfig;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.Environment;
import com.sleepycat.je.EnvironmentConfig;
import com.sleepycat.je.LockMode;

import junit.framework.TestCase;

public class SerializableTypeTest extends TestCase{
?private Person person;
?private Environment env;
?private Database db,classDB;
?private StoredClassCatalog classCatalog;
?
?public void setUp()throws Exception{
??person = new Person();
??person.setAge(12);
??person.setName("zhansan");
??person.setSex('m');
????
??EnvironmentConfig envConfig = new EnvironmentConfig();
??envConfig.setAllowCreate(true);
??env = new Environment(new File("etc/dbEnv"),envConfig);
??DatabaseConfig dbConfig = new DatabaseConfig();
??dbConfig.setAllowCreate(true);
??db = env.openDatabase(null, "myDB", dbConfig);
??classDB = env.openDatabase(null, "classDB", dbConfig);
??classCatalog = new StoredClassCatalog(classDB);
??EntryBinding dataBinding = new SerialBinding(classCatalog,Person.class);
???
??DatabaseEntry keyEntry = new DatabaseEntry(person.getName().getBytes("UTF-8"));
??DatabaseEntry dataEntry = new DatabaseEntry();
??dataBinding.objectToEntry(person, dataEntry);
??db.put(null, keyEntry, dataEntry);
?}
?
?public void testGet()throws Exception{
??EntryBinding dataBinding = new SerialBinding(classCatalog,Person.class);
??
??DatabaseEntry keyEntry = new DatabaseEntry(person.getName().getBytes("UTF-8"));
???? DatabaseEntry dataEntry = new DatabaseEntry();
???? db.get(null, keyEntry, dataEntry, LockMode.DEFAULT);
???? Person p = (Person)dataBinding.entryToObject(dataEntry);
???? assertEquals(p.getName(),person.getName());
???? assertEquals(p.getAge(),person.getAge());
???? assertEquals(p.getSex(), person.getSex());
?}
?
?public void tearDown()throws Exception{
??db.close();
??classDB.close();
??env.truncateDatabase(null, "myDB", false);
??env.truncateDatabase(null, "classDB", false);
??env.close();
?}
}

要存储的对象对应的类

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package edu.jlu.fuliang;??
?
import java.io.Serializable;??
?
public class Person implements Serializable{??
??? private String name;??
??? private int age;??
??? private char sex;??
?
??? public int getAge() {??
??????? return age;??
??? }??
?
??? public void setAge(int age) {??
??????? this.age = age;??
??? }??
?
??? public String getName() {??
??????? return name;??
??? }??
?
??? public void setName(String name) {??
??????? this.name = name;??
??? }??
?
??? public char getSex() {??
??????? return sex;??
??? }??
?
??? public void setSex(char sex) {??
??????? this.sex = sex;??
??? }??
}?

package edu.jlu.fuliang;

import java.io.Serializable;

public class Person implements Serializable{
?private String name;
?private int age;
?private char sex;

?public int getAge() {
??return age;
?}

?public void setAge(int age) {
??this.age = age;
?}

?public String getName() {
??return name;
?}

?public void setName(String name) {
??this.name = name;
?}

?public char getSex() {
??return sex;
?}

?public void setSex(char sex) {
??this.sex = sex;
?}
}

自定义元组绑定：
存储复杂对象自定义元组绑定的步骤：
1、创建要存储的对象，这个对象的类没有必要实现Serializable接口：
2、扩展com.sleepycat.bind.tuple.TupleBinding来实现自定义的Binging
3、创建2步关键的自定义binding对象
4、将创建的对象是用自定义个binding放到DatabaseEntry中
5、使用put方法存入数据库
下面的例子说明了这个过程：
自定义Binging：

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package edu.jlu.fuliang;??
?
import com.sleepycat.bind.tuple.TupleBinding;??
import com.sleepycat.bind.tuple.TupleInput;??
import com.sleepycat.bind.tuple.TupleOutput;??
?
public class PersonTupleBinding extends TupleBinding{??
?
??? @Override?
??? public Object entryToObject(TupleInput ti) {??
??????? Person person = new Person();??
??????? person.setName(ti.readString());??
??????? person.setAge(ti.readInt());??
??????? person.setSex(ti.readChar());??
??????? return person;??
??? }??
?
??? @Override?
??? public void objectToEntry(Object obj, TupleOutput output) {??
??????? Person person = (Person)obj;??
??????? output.writeString(person.getName());??
??????? output.writeInt(person.getAge());??
??????? output.writeChar(person.getSex());??
??? }??
}?

package edu.jlu.fuliang;

import com.sleepycat.bind.tuple.TupleBinding;
import com.sleepycat.bind.tuple.TupleInput;
import com.sleepycat.bind.tuple.TupleOutput;

public class PersonTupleBinding extends TupleBinding{

?@Override
?public Object entryToObject(TupleInput ti) {
??Person person = new Person();
??person.setName(ti.readString());
??person.setAge(ti.readInt());
??person.setSex(ti.readChar());
??return person;
?}

?@Override
?public void objectToEntry(Object obj, TupleOutput output) {
??Person person = (Person)obj;
??output.writeString(person.getName());
??output.writeInt(person.getAge());
??output.writeChar(person.getSex());
?}
}

put/get的使用过程：

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package edu.jlu.fuliang;??
?
import java.io.File;??
import com.sleepycat.je.Database;??
import com.sleepycat.je.DatabaseConfig;??
import com.sleepycat.je.DatabaseEntry;??
import com.sleepycat.je.DatabaseException;??
import com.sleepycat.je.Environment;??
import com.sleepycat.je.EnvironmentConfig;??
import com.sleepycat.je.LockMode;??
?
import junit.framework.TestCase;??
?
public class CustomTupleBindingTest extends TestCase{??
??? private Person person;??
??? private Environment env;??
??? private Database db;??
??????
??? public void setUp()throws Exception{??
??????? person = new Person();??
??????? person.setAge(12);??
??????? person.setName("zhansan");??
??????? person.setSex('m');??
??????????
??????????
??????? EnvironmentConfig envConfig = new EnvironmentConfig();??
??????? envConfig.setAllowCreate(true);??
??????? env = new Environment(new File("etc/dbEnv"),envConfig);??
??????? DatabaseConfig dbConfig = new DatabaseConfig();??
??????? dbConfig.setAllowCreate(true);??
??????? db = env.openDatabase(null, "myDB", dbConfig);??
??????? PersonTupleBinding binding = new PersonTupleBinding();??
??????? DatabaseEntry keyEntry = new DatabaseEntry(person.getName().getBytes("UTF-8"));??
??????? DatabaseEntry dataEntry = new DatabaseEntry();??
??????? binding.objectToEntry(person, dataEntry);??
??????? db.put(null, keyEntry, dataEntry);??
??????????
??? }??
??????
??? public void testGet()throws Exception{??
??????? PersonTupleBinding binding = new PersonTupleBinding();??
??????????
??????? DatabaseEntry keyEntry = new DatabaseEntry(person.getName().getBytes("UTF-8"));??
??????? DatabaseEntry dataEntry = new DatabaseEntry();??
??????? db.get(null, keyEntry, dataEntry, LockMode.DEFAULT);??
??????? Person p = (Person)binding.entryToObject(dataEntry);??
??????? assertEquals(p.getName(),person.getName());??
??????? assertEquals(p.getAge(),person.getAge());??
??????? assertEquals(p.getSex(), person.getSex());??
??? }??
??? public void tearDown()throws Exception{??
??????? db.close();??
??????? env.truncateDatabase(null, "myDB", false);??
??????? env.close();??
??? }??
}?

Berkely DB Java Edition学习札记

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