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Berkeley DB Java Edition 简介

时间：2022-03-13 22:55

JE的记录包含两部分,key键值和value数据值，这两个值都是通过DatabaseEntry对象封装起来，所以说如果要使用记录，则你必须创建两个DatabaseEntry对象，一个是用来做为key，另外一个是做为value.

DatabaseEntry能够支持任何的能够转换为bytes数组形式的基本数据。包括所有的JAVA基本类型和可序列化的对象.

使用记录

示例一：把字符串转换DatabaseEntry

示例二：把DatabaseEntry里的数据转换成字符串

读和写database 记录

读和写database记录的时候大体是基本一样的，唯一有区别的是每个key写是否允许写多条记录，默认情况下是不支持多条记录的。

a) 你可以使用如下方法向database 里添加记录

l Database.put()

向database中添加一条记录。如果你的database不支持一个key对应多个data或当前database中已经存在该key了，则使用此方法将使用新的值覆盖旧的值。

l Database.putNoOverwrite()

向database中添加新值但如果原先已经有了该key，则不覆盖。不管database是否允许支持多重记录(一个key对应多个value),只要存在该key就不允许添加，并且返回perationStatus.KEYEXIST信息。

l Database.putNoDupData()

想database中添加一条记录，如果database中已经存在了相同的 key和value则返回 OperationStatus.KEYEXIST.

使用示例：

b) 你可以使用如下方法从database 里读取记录

1. Database.get()

基本的读记录的方法，通过key的方式来匹配，如果没有改记录则返回OperationStatus.NOTFOUND。

l Database.getSearchBoth()

通过key和value来同时匹配，同样如果没有记录匹配key和value则会返回OperationStatus.NOTFOUND。

使用示例：

c) 删除记录

可以使用Database.delete()这个方法来删除记录。如果你的database支持多重记录，则当前key下的所有记录都会被删除，如果只想删除多重记录中的一条则可以使用游标来删除。

当然你也可以使用Environment.truncateDatabase()这个方法来清空database 中的所有记录。

使用示例：

package je.gettingStarted;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

...

try {

String aKey = "myFirstKey";

DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));

myDatabase.delete(null, theKey);

} catch (Exception e) {

}

d) 提交事务

当你对database进行了写操作的时候，你的修改不一定马上就能生效，有的时候他仅仅是缓存在RAM中，如果想让你的修改立即生效，则可以使用Environment.sync()方法来把数据同步到磁盘中去。

e) 不同类型的数据的处理

1. 你可以使用DatabaseEntry来绑定基本的JAVA数据类型，主要有String、Character、Boolean、Byte、Short、Integer、Long、Float、Double.

使用示例一：

package je.gettingStarted;

import com.sleepycat.bind.EntryBinding;

import com.sleepycat.bind.tuple.TupleBinding;

import com.sleepycat.je.DatabaseEntry;

...

try {

String aKey = "myLong";

DatabaseEntry theKey = new

DatabaseEntry(aKey.getBytes("UTF-8"));

Long myLong = new Long(123456789l);

DatabaseEntry theData = new DatabaseEntry();

EntryBinding myBinding =

TupleBinding.getPrimitiveBinding(Long.class);

myBinding.objectToEntry(myLong, theData);

myDatabase.put(null, theKey, theData);

} catch (Exception e) {

// Exception handling goes here

}

使用示例二：

package je.gettingStarted;

import com.sleepycat.bind.EntryBinding;

import com.sleepycat.bind.tuple.TupleBinding;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.LockMode;

import com.sleepycat.je.OperationStatus;

...

Database myDatabase = null;

try {

String aKey = "myLong";

DatabaseEntry theKey = new

DatabaseEntry(aKey.getBytes("UTF-8"));

DatabaseEntry theData = new DatabaseEntry();

EntryBinding myBinding =

TupleBinding.getPrimitiveBinding(Long.class);

OperationStatus retVal = myDatabase.get(null, theKey, theData,

LockMode.DEFAULT);

String retKey = null;

if (retVal == OperationStatus.SUCCESS) {

Long theLong = (Long) myBinding.entryToObject(theData);

retKey = new String(theKey.getData(), "UTF-8");

System.out.println("For key: ‘" + retKey + "‘ found Long: ‘" +

theLong + "‘.");

} else {

System.out.println("No record found for key ‘" + retKey + "‘.");

}

} catch (Exception e) {

// Exception handling goes here

}

2. 可序列化的对象的绑定

1. 首先你需要创建一个可序列化对象

2. 打开或创建你的database，你需要两个，一个用来存储你的数据，另外一个用来存储类信息。

3. 实例化catalog类，这个时候你可以使用com.sleepycat.bind.serial.StoredClassCatalog,来存储你的类信息。

4. 通过com.sleepycat.bind.serial.SerialBinding来绑定数据和类。

5. 绑定并存储数据。

示例：

l 创建一个可序列化的对象

package je.gettingStarted;

import java.io.Serializable;

public class MyData implements Serializable {

private long longData;

private double doubleData;

private String description;

MyData() {

longData = 0;

doubleData = 0.0;

description = null;

}

public void setLong(long data) {

longData = data;

}

public void setDouble(double data) {

doubleData = data;

}

public void setDescription(String data) {

description = data;

}

public long getLong() {

return longData;

}

public double getDouble() {

return doubleData;

}

public String getDescription() {

return description;

}

l 存储数据

package je.gettingStarted;

import com.sleepycat.bind.EntryBinding;

import com.sleepycat.bind.serial.StoredClassCatalog;

import com.sleepycat.bind.serial.SerialBinding;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseConfig;

import com.sleepycat.je.DatabaseEntry;

...

String aKey = "myData";

MyData data2Store = new MyData();

data2Store.setLong(123456789l);

data2Store.setDouble(1234.9876543);

data2Store.setDescription("A test instance of this class");

try {

DatabaseConfig myDbConfig = new DatabaseConfig();

myDbConfig.setAllowCreate(true);

myDbConfig.setSortedDuplicates(true);

Database myDatabase = myDbEnv.openDatabase(null, "myDb", myDbConfig);

myDbConfig.setSortedDuplicates(false);

//打开用来存储类信息的库

Database myClassDb = myDbEnv.openDatabase(null, "classDb", myDbConfig);

// 3）创建catalog

StoredClassCatalog classCatalog = new StoredClassCatalog(myClassDb);

// 4）绑定数据和类

EntryBinding dataBinding = new SerialBinding(classCatalog,

MyData.class);

DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));

// 向DatabaseEntry里写数据

DatabaseEntry theData = new DatabaseEntry();

dataBinding.objectToEntry(data2Store, theData);

myDatabase.put(null, theKey, theData);

} catch (Exception e) {

// 错误处理

}

l 读数据

package je.gettingStarted;

import com.sleepycat.bind.EntryBinding;

import com.sleepycat.bind.serial.StoredClassCatalog;

import com.sleepycat.bind.serial.SerialBinding;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseConfig;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.LockMode;

...

// The key data.

String aKey = "myData";

try {

DatabaseConfig myDbConfig = new DatabaseConfig();

myDbConfig.setAllowCreate(false);

Database myDatabase = myDbEnv.openDatabase(null, "myDb", myDbConfig);

//用来存储类信息的库

Database myClassDb = myDbEnv.openDatabase(null, "classDb", myDbConfig);

// 实例化catalog

StoredClassCatalog classCatalog = new StoredClassCatalog(myClassDb);

// 创建绑定对象

EntryBinding dataBinding = new SerialBinding(classCatalog,

MyData.class);

DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));

DatabaseEntry theData = new DatabaseEntry();

myDatabase.get(null, theKey, theData, LockMode.DEFAULT);

// Recreate the MyData object from the retrieved DatabaseEntry using

// 根据存储的类信息还原数据

MyData retrievedData=(MyData)dataBinding.entryToObject(theData);

} catch (Exception e) {

// Exception handling goes here

}

3. 自定义对象的绑定

使用tuple binding 来绑定自定义数据的步骤

①. 实例化你要存储的对象

②. 通过com.sleepycat.bind.tuple.TupleBinding class来创建一个tuple binding。

③. 创建一个database，跟序列化的对象不同，你只需要创建一个。

④. 通过继承第二步的类来创建一个entry binding 对象。

⑤. 存储和使用数据

使用示例：

l 创建要存储的对象

package je.gettingStarted;

public class MyData2 {

private long longData;

private Double doubleData;

private String description;

public MyData2() {

longData = 0;

doubleData = new Double(0.0);

description = "";

}

public void setLong(long data) {

longData = data;

}

public void setDouble(Double data) {

doubleData = data;

}

public void setString(String data) {

description = data;

}

public long getLong() {

return longData;

}

public Double getDouble() {

return doubleData;

}

public String getString() {

return description;

}

l 创建一个TupleBinding对象

package je.gettingStarted;

import com.sleepycat.bind.tuple.TupleBinding;

import com.sleepycat.bind.tuple.TupleInput;

import com.sleepycat.bind.tuple.TupleOutput;

public class MyTupleBinding extends TupleBinding {

// 把对象转换成TupleOutput

public void objectToEntry(Object object, TupleOutput to) {

MyData2 myData = (MyData2)object;

to.writeDouble(myData.getDouble().doubleValue());

to.writeLong(myData.getLong());

to.writeString(myData.getString());

}

//把TupleInput转换为对象

public Object entryToObject(TupleInput ti) {

Double theDouble = new Double(ti.readDouble());

long theLong = ti.readLong();

String theString = ti.readString();

MyData2 myData = new MyData2();

myData.setDouble(theDouble);

myData.setLong(theLong);

myData.setString(theString);

return myData;

}

l 读和写数据

package je.gettingStarted;

import com.sleepycat.bind.tuple.TupleBinding;

import com.sleepycat.je.DatabaseEntry;

...

TupleBinding keyBinding = new MyTupleBinding();

MyData2 theKeyData = new MyData2();

theKeyData.setLong(123456789l);

theKeyData.setDouble(new Double(12345.6789));

theKeyData.setString("My key data");

DatabaseEntry myDate = new DatabaseEntry();

try {

// 把theKeyData 存储到DatabaseEntry里

keyBinding.objectToEntry(theKeyData, myDate);

...

// Database 进行了一些读和写操作

...

// Retrieve the key data

theKeyData = (MyData2) keyBinding.entryToObject(myDate);

} catch (Exception e) {

// 错误处理

}

f) 使用比较器

JE是使用BTrees来组织结构的，这意味着当对database的读和写需要涉及BTrees间的节点比较。这些比较在key间是经常的发生的。如果你的database支持多重记录，那么也会存在data间的比较。

默认的情况JE的比较器是按照字节的方式来进行比较的，这通常情况下能处理大多数的情况。但有的时候确实需要自定义比较器用于特殊的通途，比如说按照key来排序。

l 创建自己的比较器

其实很简单，只要你重写Comparator class中的比较方法（compare）就可以了，通过Comparator.compare()会传递给你两个byte 数组形式的值，如果你知道结构，则可以根据你自己定义的方法来进行比较

示例：

package je.gettingStarted;

import java.util.Comparator;

public class MyDataComparator implements Comparator {

public MyDataComparator() {}

public int compare(Object d1, Object d2) {

byte[] b1 = (byte[])d1;

byte[] b2 = (byte[])d2;

String s1 = new String(b1, "UTF-8");

String s2 = new String(b2, "UTF-8");

return s1.compareTo(s2);

}

l 让database使用你自定义的比较器

如果你想改变database中基本的排序方式，你只能重新创建database并重新导入数据。

①. DatabaseConfig.setBtreeComparator()

用于在database里两个key的比较

②. DatabaseConfig.setOverrideBtreeComparator()

如果为true则代表让database使用 DatabaseConfig.setBtreeComparator()设置的比较器来代替默认的比较器。

③. DatabaseConfig.setDuplicateComparator()

用于database可以使用多重记录的时候的data的比较。

④. DatabaseConfig.setOverrideDuplicateComparator()

如果为true则代表让database使用 DatabaseConfig. setDuplicateComparator()设置的比较器来代替默认的比较器。

使用示例：

package je.gettingStarted;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseConfig;

import com.sleepycat.je.DatabaseException;

import java.util.Comparator;

...

try {

DatabaseConfig myDbConfig = new DatabaseConfig();

myDbConfig.setAllowCreate(true);

// 设置要使用的比较器

myDbConfig.setDuplicateComparator(MyDataComparator.class);

// 使用自己定义的比较器

myDbConfig.setSortedDuplicates(true);

Database myDatabase = myDbEnv.openDatabase(null, "myDb", myDbConfig);

} catch (DatabaseException dbe) {

// Exception handling goes here

}

package je.gettingStarted;

import com.sleepycat.je.Cursor;

import com.sleepycat.je.CursorConfig;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.Environment;

import java.io.File;

...

Environment myDbEnvironment = null;

Database myDatabase = null;

Cursor myCursor = null;

try {

myDbEnvironment = new Environment(new File("/export/dbEnv"), null);

myDatabase = myDbEnvironment.openDatabase(null, "myDB", null);

myCursor = myDatabase.openCursor(null, null);

} catch (DatabaseException dbe) {

// Exception handling goes here ...

}

package je.gettingStarted;

import com.sleepycat.je.Cursor;

import com.sleepycat.je.Database;

import com.sleepycat.je.Environment;

...

try {

...

} catch ... {

} finally {

try {

if (myCursor != null) {

myCursor.close();

}

if (myDatabase != null) {

myDatabase.close();

}

if (myDbEnvironment != null) {

myDbEnvironment.close();

}

} catch(DatabaseException dbe) {

System.err.println("Error in close: " + dbe.toString());

}

package je.gettingStarted;

import com.sleepycat.je.Cursor;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.LockMode;

import com.sleepycat.je.OperationStatus;

...

Cursor cursor = null;

try {

cursor = myDatabase.openCursor(null, null);

DatabaseEntry foundKey = new DatabaseEntry();

DatabaseEntry foundData = new DatabaseEntry();

// 通过cursor.getNex方法来遍历记录

while (cursor.getNext(foundKey, foundData, LockMode.DEFAULT) ==

OperationStatus.SUCCESS) {

String keyString = new String(foundKey.getData(), "UTF-8");

String dataString = new String(foundData.getData(), "UTF-8");

System.out.println("Key | Data : " + keyString + " | " +

dataString + "");

}

} catch (DatabaseException de) {

System.err.println("Error accessing database." + de);

} finally {

// 使用后必须关闭游标

cursor.close();

}

package je.gettingStarted;

import com.sleepycat.je.Cursor;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.LockMode;

import com.sleepycat.je.OperationStatus;

...

Cursor cursor = null;

try {

...

// Open the cursor.

cursor = myDatabase.openCursor(null, null);

DatabaseEntry foundKey = new DatabaseEntry();

DatabaseEntry foundData = new DatabaseEntry();

// 使用cursor.getPrev方法来遍历游标获取数据

while (cursor.getPrev(foundKey, foundData, LockMode.DEFAULT)

== OperationStatus.SUCCESS) {

String theKey = new String(foundKey.getData(), "UTF-8");

String theData = new String(foundData.getData(), "UTF-8");

System.out.println("Key | Data : " + theKey + " | " + theData + "");

}

} catch (DatabaseException de) {

System.err.println("Error accessing database." + de);

} finally {

// 使用后必须关闭游标

cursor.close();

}

查询的key

查询的data

游标指向

Alaska

Alaska/Fairbanks

Arizona

Arizona/Florence

Alaska

Alaska/Anchorage

package je.gettingStarted;

import com.sleepycat.je.Cursor;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.LockMode;

import com.sleepycat.je.OperationStatus;

...

String searchKey = "Alaska";

String searchData = "Fa";

Cursor cursor = null;

try {

...

cursor = myDatabase.openCursor(null, null);

DatabaseEntry theKey =

new DatabaseEntry(searchKey.getBytes("UTF-8"));

DatabaseEntry theData =

new DatabaseEntry(searchData.getBytes("UTF-8"));

cursor = myDatabase.openCursor(null, null);

OperationStatus retVal = cursor.getSearchBothRange(theKey,

theData, LockMode.DEFAULT);

if (retVal == OperationStatus.NOTFOUND) {

System.out.println(searchKey + "/" + searchData +

" not matched in database " +

myDatabase.getDatabaseName());

} else {

String foundKey = new String(theKey.getData(), "UTF-8");

String foundData = new String(theData.getData(), "UTF-8");

System.out.println("Found record " + foundKey + "/" + foundData +

"for search key/data: " + searchKey +

"/" + searchData);

}

} catch (Exception e) {

// Exception handling goes here

} finally {

cursor.close();

}

package je.gettingStarted;

import com.sleepycat.je.Cursor;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.LockMode;

import com.sleepycat.je.OperationStatus;

...

Cursor cursor = null;

try {

...

// Create DatabaseEntry objects

// searchKey is some String.

DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8"));

DatabaseEntry theData = new DatabaseEntry();

cursor = myDatabase.openCursor(null, null);

OperationStatus retVal = cursor.getSearchKey(theKey,

theData, LockMode.DEFAULT);

// 如果count超过一个，则遍历

if (cursor.count() > 1) {

while (retVal == OperationStatus.SUCCESS) {

String keyString = new String(theKey.getData(), "UTF-8");

String dataString = new String(theData.getData(), "UTF-8");

System.out.println("Key | Data : " + keyString + " | " +

dataString + "");

retVal = cursor.getNextDup(theKey, theData, LockMode.DEFAULT);

}

} catch (Exception e) {

// Exception handling goes here

} finally {

// Make sure to close the cursor

cursor.close();

}

如果存在相同的key在database里则返OperationStatus.KEYEXIS，

如果不存在key则添加数据。

package je.gettingStarted;

import com.sleepycat.je.Cursor;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.OperationStatus;

...

String key1str = "My first string";

String data1str = "My first data";

String key2str = "My second string";

String data2str = "My second data";

String data3str = "My third data";

Cursor cursor = null;

try {

...

DatabaseEntry key1 = new DatabaseEntry(key1str.getBytes("UTF-8"));

DatabaseEntry data1 = new DatabaseEntry(data1str.getBytes("UTF-8"));

DatabaseEntry key2 = new DatabaseEntry(key2str.getBytes("UTF-8"));

DatabaseEntry data2 = new DatabaseEntry(data2str.getBytes("UTF-8"));

DatabaseEntry data3 = new DatabaseEntry(data3str.getBytes("UTF-8"));

cursor = myDatabase.openCursor(null, null);

OperationStatus retVal = cursor.put(key1, data1); // 添加成功

retVal = cursor.put(key2, data2); // 添加成功

retVal = cursor.put(key2, data3); // 如果允许多重记录则添加成功 //否则添加失败

} catch (Exception e) {

// Exception handling goes here

} finally {

// Make sure to close the cursor

cursor.close();

}

package je.gettingStarted;

import com.sleepycat.je.Cursor;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.LockMode;

import com.sleepycat.je.OperationStatus;

...

Cursor cursor = null;

try {

...

DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8"));

DatabaseEntry theData = new DatabaseEntry();

cursor = myDatabase.openCursor(null, null);

OperationStatus retVal = cursor.getSearchKey(theKey, theData, LockMode.DEFAULT);

//如果date不是多重记录.

if (cursor.count() == 1) {

System.out.println("Deleting " +

new String(theKey.getData(), "UTF-8") +

"|" +

new String(theData.getData(), "UTF-8"));

cursor.delete();//删除当前记录

}

} catch (Exception e) {

// Exception handling goes here

} finally {

// Make sure to close the cursor

cursor.close();

}

import com.sleepycat.je.Cursor;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.LockMode;

import com.sleepycat.je.OperationStatus;

...

Cursor cursor = null;

try {

...

DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8"));

DatabaseEntry theData = new DatabaseEntry();

cursor = myDatabase.openCursor(null, null);

OperationStatus retVal = cursor.getSearchKey(theKey, theData,

LockMode.DEFAULT);

//将要被替换的值

String replaceStr = "My replacement string";

DatabaseEntry replacementData =

new DatabaseEntry(replaceStr.getBytes("UTF-8"));

cursor.putCurrent(replacementData);//把当前位置用新值替换

} catch (Exception e) {

// Exception handling goes here

} finally {

// Make sure to close the cursor

cursor.close();

}

package je.gettingStarted;

import com.sleepycat.bind.tuple.TupleBinding;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseConfig;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.Environment;

import com.sleepycat.je.SecondaryDatabase;

import com.sleepycat.je.SecondaryConfig;

import java.io.File;

...

DatabaseConfig myDbConfig = new DatabaseConfig();

//二级库的配置信息

SecondaryConfig mySecConfig = new SecondaryConfig();

myDbConfig.setAllowCreate(true);

mySecConfig.setAllowCreate(true);

// 通常二级库经常是允许多重记录的

mySecConfig.setSortedDuplicates(true);

// primary database

Environment myEnv = null;

Database myDb = null;

SecondaryDatabase mySecDb = null;

try {

//打开primary库

String dbName = "myPrimaryDatabase";

myEnv = new Environment(new File("/tmp/JEENV"), null);

myDb = myEnv.openDatabase(null, dbName, myDbConfig);

//创建tuple binding

TupleBinding myTupleBinding = new MyTupleBinding();

// 创建二级库的key创建器

FullNameKeyCreator keyCreator = new FullNameKeyCreator(myTupleBinding);

// 设置二级库的创建器

mySecConfig.setKeyCreator(keyCreator);

//打开二级库

String secDbName = "mySecondaryDatabase";

mySecDb = myEnv.openSecondaryDatabase(null, secDbName,

myDb, mySecConfig);

} catch (DatabaseException de) {

// 错误处理

}

try {

if (mySecDb != null) {

mySecDb.close();

}

if (myDb != null) {

myDb.close();

}

if (myEnv != null) {

myEnv.close();

}

} catch (DatabaseException dbe) {

// Exception handling goes here

}

package je.gettingStarted;

public class PersonData {

private String userID;

private String surname;

private String familiarName;

public PersonData(String userID, String surname, String familiarName) {

this.userID = userID;

this.surname = surname;

this.familiarName = familiarName;

}

public String getUserID() {

return userID;

}

public String getSurname() {

return surname;

}

public String getFamiliarName() {

return familiarName;

}

package je.gettingStarted;、

import com.sleepycat.bind.tuple.TupleBinding;

import com.sleepycat.je.SecondaryKeyCreator;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.SecondaryDatabase;

import java.io.IOException;

public class FullNameKeyCreator implements SecondaryKeyCreator {

private TupleBinding theBinding;

public FullNameKeyCreator(TupleBinding theBinding1) {

theBinding = theBinding1;

}

public boolean createSecondaryKey(SecondaryDatabase secDb,

DatabaseEntry keyEntry,

DatabaseEntry dataEntry,

DatabaseEntry resultEntry) {

try {

PersonData pd =

(PersonData) theBinding.entryToObject(dataEntry);

String fullName = pd.getFamiliarName() + " " +

pd.getSurname();

resultEntry.setData(fullName.getBytes("UTF-8"));

} catch (IOException willNeverOccur) {}

return true;

}

package je.gettingStarted;

import com.sleepycat.bind.tuple.TupleBinding;

import com.sleepycat.je.Database;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.Environment;

import com.sleepycat.je.SecondaryDatabase;

import com.sleepycat.je.SecondaryConfig;

...

Environment myEnv = null;

Database myDb = null;

SecondaryDatabase mySecDb = null;

try {

...

TupleBinding myDataBinding = new MyTupleBinding();

//创建键创建器

FullNameKeyCreator fnkc = new FullNameKeyCreator(myDataBinding);

SecondaryConfig mySecConfig = new SecondaryConfig();

//设置键创建器

mySecConfig.setKeyCreator(fnkc);

String secDbName = "mySecondaryDatabase";

mySecDb = myEnv.openSecondaryDatabase(null, secDbName, myDb,

mySecConfig);

} catch (DatabaseException de) {

// Exception handling goes here

} finally {

try {

if (mySecDb != null) {

mySecDb.close();

}

if (myDb != null) {

myDb.close();

}

if (myEnv != null) {

myEnv.close();

}

} catch (DatabaseException dbe) {

// Exception handling goes here

}

package je.gettingStarted;

import com.sleepycat.je.DatabaseEntry;

import com.sleepycat.je.LockMode;

import com.sleepycat.je.OperationStatus;

import com.sleepycat.je.SecondaryDatabase;

...

try {

...

String searchName = "John Doe";

DatabaseEntry searchKey =

new DatabaseEntry(searchName.getBytes("UTF-8"));

DatabaseEntry primaryKey = new DatabaseEntry();

DatabaseEntry primar

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