java使用bdb手记(Berkeley DB Java Api记录)

在线Berkeley DB Java Edition API:

http://www.oracle.com/technology/documentation/berkeley-db/je/java/index.html

Berkeley DB是一个开放源代码的内嵌式数据库管理系统,能够为应用程序提供高性能的数据管理服务。应用它程序员只需要调用一些简单的API就可以完成对数据的访问和管理。与常用的数据库管理系统(如MySQL和Oracle等)有所不同,在Berkeley DB中并没有数据库服务器的概念。应用程序不需要事先同数据库服务建立起网络连接,而是通过内嵌在程序中的Berkeley DB函数库来完成对数据的保存、查询、修改和删除等操作。

用java来操作BDB,需要jar包je-3.3.62.jar

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;
private Database db;

public MyBerkeleyDB() {

}

public void setUp(String path, long cacheSize) {
EnvironmentConfig envConfig = new EnvironmentConfig();
envConfig.setAllowCreate(true);
envConfig.setCacheSize(cacheSize);
try {
env = new Environment(new File(path),envConfig);
} catch (DatabaseException e) {
e.printStackTrace();
} }

public void open(String dbName) {
DatabaseConfig dbConfig = new DatabaseConfig();
dbConfig.setAllowCreate(true);
try {
db = env.openDatabase(null, dbName, dbConfig);
} catch (DatabaseException e) {
e.printStackTrace();
} }

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

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());
} return null;
}

public boolean put(String key, String value) throws Exception {
byte[] theKey = key.getBytes("UTF-8");
byte[] theValue = value.getBytes("UTF-8");
OperationStatus status = db.put(null, new DatabaseEntry(theKey),
new DatabaseEntry(theValue));
if(status == OperationStatus.SUCCESS) {
return true;
} return false;
}

public static void main(String[] args) {
MyBerkeleyDB mbdb = new MyBerkeleyDB();
mbdb.setUp("C:\\bdb", 1000000);
mbdb.open("myDB");
System.out.println("开始向Berkeley DB中存入数据...");
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();
} }
mbdb.close();

} 取出和删除 不言自明


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