Berkeley DB 开源的文件数据库

开源的文件数据库，介于关系数据库和内存数据库之间，按键值对方式存储

下面是一个实例，是网上抄的，然后自己本机运行的

package org;

import java.io.File;
import java.io.UnsupportedEncodingException;
import java.util.concurrent.TimeUnit;

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 com.sleepycat.je.OperationStatus;
import com.sleepycat.je.Transaction;
import com.sleepycat.je.TransactionConfig;

public class BerkeleyDB {
	
	private Environment environment = null;	//数据库环境		
	private DatabaseConfig dbConfig = null;	//数据库配置
	private Database database = null;	//数据库对象
	private String fileName = "D:\\wzx";
	private String dbName = "wzx";
	
	public void openDatabase(){
		EnvironmentConfig envConfig = new EnvironmentConfig();
		envConfig.setAllowCreate(true);
		envConfig.setTransactional(true);
		envConfig.setReadOnly(false);
		envConfig.setTxnTimeout(10000, TimeUnit.MILLISECONDS);
		envConfig.setLockTimeout(10000, TimeUnit.MILLISECONDS);
		
		File file = new File(fileName);
		if(!file.exists()){
			file.mkdirs();
		}
		environment = new Environment(file, envConfig);
		dbConfig = new DatabaseConfig();
		dbConfig.setAllowCreate(true);
		dbConfig.setTransactional(true);
		dbConfig.setReadOnly(false);
		
		if(database == null)
			database = environment.openDatabase(null, dbName, dbConfig);
		
	}
	
	public boolean insert(String key, String value, boolean isOverWrite){
		
		try {
			DatabaseEntry theKey = new DatabaseEntry(key.getBytes("UTF-8"));
			DatabaseEntry theData = new DatabaseEntry(value.getBytes("UTF-8"));
			OperationStatus os = null;
			Transaction transaction = null;
			
			TransactionConfig txnConfig = new TransactionConfig();
			txnConfig.setSerializableIsolation(true);
			
			transaction = environment.beginTransaction(null, txnConfig);
			if(isOverWrite){
				os = database.put(transaction, theKey, theData);
			}else{
				os = database.putNoOverwrite(transaction, theKey, theData);
			}
			transaction.commit();
			
			if(os == OperationStatus.SUCCESS){
				return true;
			}else{
				return false;
			}
			
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		
		return false;
	}
	
	public String query(String key){
		try {
			DatabaseEntry theKey = new DatabaseEntry(key.getBytes("UTF-8"));
			DatabaseEntry theData = new DatabaseEntry();
			
			Transaction transaction = null;
			
			TransactionConfig txnConfig = new TransactionConfig();
			txnConfig.setSerializableIsolation(true);
			
			transaction = environment.beginTransaction(null, txnConfig);
			
			OperationStatus os = database.get(transaction, theKey, theData, LockMode.DEFAULT);
			transaction.commit();
			
			if(os == OperationStatus.SUCCESS){
				String value = new String(theData.getData(), "UTF-8");
				return value;
			}else{
				return "";
			}
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null;
	}
	
	public void close(){
		if(database != null){
			database.close();
		}
		if(environment != null){
			environment.cleanLog();
			environment.close();
		}
	}
	
	public static void main(String[] args) {
		BerkeleyDB berkeleyDb = new BerkeleyDB();
		berkeleyDb.openDatabase();
		/*berkeleyDb.insert("China", "北京", true);
		berkeleyDb.insert("US", "纽约", true);*/
		System.out.println(berkeleyDb.query("China"));
		
	}
	
	
	
}