三、一个简单的BDB JE例子

package test;

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 com.sleepycat.je.OperationStatus;

public class MyBerkeleyDB {
private Environment env;
public Environment getEnv() {
return env;
}

private Database db;

public MyBerkeleyDB() {
}

/**
* 构建数据库的开发环境
*
* @param path   数据库开发环境的目录
* @param cacheSize  配置缓存大小
*/
public void setUp(String path, long cacheSize) {
EnvironmentConfig envConfig = new EnvironmentConfig();
//当设置为true时，说明若没有数据库的环境时，可以打开。否则就不能打开
envConfig.setAllowCreate(true);
//envConfig.setReadOnly(true);
envConfig.setCacheSize(cacheSize);
//设置事务
//envConfig.setTransactional(true);
//当提交事务的时候是否把缓存中的内容同步到磁盘中去。true 表示不同步，也就是说不写磁盘
//envConfig.setTxnNoSync(true);
//当提交事务的时候，是否把缓冲的log写到磁盘上,true 表示不同步，也就是说不写磁盘
//envConfig.setTxnWriteNoSync(true);
try {
env = new Environment(new File(path), envConfig);
} catch (DatabaseException e) {
e.printStackTrace();
}
}

/**
* 构建数据库
*
* @param dbName 数据库的名称
*/
public void open(String dbName) {
DatabaseConfig dbConfig = new DatabaseConfig();
//设置数据的是否可以创建的属性
dbConfig.setAllowCreate(true);
try {
db = env.openDatabase(null, dbName, dbConfig);
} catch (DatabaseException e) {
e.printStackTrace();
}
}

/**
* 关闭berkeley db
*/
public void close() {
try {
if (db != null) {
db.close();
}
if (env != null) {
env.cleanLog();
env.close();
}
} catch (DatabaseException e) {
e.printStackTrace();
}
}

/**
* 通过key得到数据
* @param key   berkeley db中的key
* @return
* @throws Exception
*/
public String get(String key) throws Exception {
DatabaseEntry queryKey = new DatabaseEntry();
DatabaseEntry value = new DatabaseEntry();
queryKey.setData(key.getBytes("UTF-8"));
OperationStatus status = db
.get(null, queryKey, value, LockMode.DEFAULT);
if (status == OperationStatus.SUCCESS) {
return new String(value.getData(),"utf-8");
}
return null;
}

/**
* 向berkeley db中存入数据
* @param key  存入berkeley db时的键
* @param value  存入berkeley db时的值
* @return
* @throws Exception
*/
public boolean put(String key, String value) throws Exception {
byte[] theKey = key.getBytes("UTF-8");
byte[] theValue = value.getBytes("UTF-8");
/**
* Berkeley DB中的记录包括两个字段，就是键和值，
* 并且这些键和值都必须是com.sleepycat.je.DatabaseEntry类的实例。
*/
OperationStatus status = db.put(null, new DatabaseEntry(theKey),
new DatabaseEntry(theValue));
if (status == OperationStatus.SUCCESS) {
return true;
}
return false;
}
/**
* 通过
* @param key
* @return
* @throws Exception
*/
public boolean del(String key) throws Exception{
DatabaseEntry queryKey = new DatabaseEntry();
queryKey.setData(key.getBytes("UTF-8"));
OperationStatus status=db.delete(null, queryKey);
if(status==OperationStatus.SUCCESS){
return true;
}
return false;
}
public static void main(String[] args) {
MyBerkeleyDB mbdb = new MyBerkeleyDB();
//必须先在你的C盘中创建文件夹bdb
mbdb.setUp("C://bdb", 1000000);
mbdb.open("myDB");
try {
System.out.println(mbdb.getEnv().getConfig());
} catch (DatabaseException e) {
e.printStackTrace();
}
System.out.println("开始向Berkeley db 中输入数据...");
for (int i = 0; i < 20; i++) {
try {
String key = "myKey" + i;
String value = "myValue" + i;
//System.out.println("[" + key + ":" + value + "]");
mbdb.put(key, value);
} catch (Exception e) {
e.printStackTrace();
}
}
try {
System.out.println(mbdb.get("myKey2"));
} catch (Exception e) {
e.printStackTrace();
}
try {
if(mbdb.del("myKey2")){
System.out.println("ture");
}else{
System.out.println("false");
}
} catch (Exception e) {
e.printStackTrace();
}
mbdb.close();

}
}