.getBytes("utf-8"));
System.out.println(" ---- > put data with key :" + key);
OperationStatus status = myDatabase.put(null, keyEntry, valEntry);
System.out.println(" ---- > put status: " + status);
//查询
System.out.println(" ---- > get key :" + key);
DatabaseEntry valEntry4Get = new DatabaseEntry();
status = myDatabase.get(null, keyEntry, valEntry4Get,
LockMode.DEFAULT);
if (status == OperationStatus.SUCCESS) {
value = new String(valEntry4Get.getData(), "utf-8");
System.out.println(" ---- > get key success value:" + value);
} else {
System.out.println(" ---- > get key failed.");
}
//更新
System.out.println(" ---- > update data with key :" + key);
value = "Hello Google";
status = myDatabase.put(null, keyEntry,
new DatabaseEntry(value.getBytes("utf-8")));
System.out.println(" ---- > update status: " + status);
System.out.println(" ---- > after update get key :" + key);
status = myDatabase.get(null, keyEntry, valEntry4Get,
LockMode.DEFAULT);
if (status == OperationStatus.SUCCESS) {
value = new String(valEntry4Get.getData(), "utf-8");
System.out.println(" ---- > get success key value:" + value);
} else {
System.out.println(" ---- > get key value failed.");
}
//删除
System.out.println(" ---- > delete key :" + key);
status = myDatabase.delete(null, keyEntry);
System.out.println(" ---- > delete status: " + status);
System.out.println(" ---- > after delete get key :" + key);
status = myDatabase.get(null, keyEntry, valEntry4Get,
LockMode.DEFAULT);
if (status == OperationStatus.SUCCESS) {
value = new String(valEntry4Get.getData(), "utf-8");
System.out.println(" ---- > get success key value:" + value);
} else {
System.out.println(" ---- > get key value failed.");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (null != myDatabase) {
myDatabase.close();
}
if (null != mydbEnv) {
// 在关闭环境前清理下日志
mydbEnv.cleanLog();
mydbEnv.close();
mydbEnv = null;
}
}
}
/**
* @param args
*/
public static void main(String[] args) {
System.out.println(" ==== >
Demo Test Start < ====");
String envHomePath = "D:/test";
String databaseName = "first-db";
SimpleDemo.testSimpleData(envHomePath, databaseName);
System.out.println(" ==== > Demo Test End < ====");
}
}
自定义TupleBinding来对复杂对象的读写
首先自定义一个类继承TupleBinding，并把模型WebURL要存入DB的属性加上：
public class WebURLTupleBinding extends TupleBinding {
@Override
public WebURL entryToObject(TupleInput input) {
WebURL webURL = new WebURL();
webURL.setURL(input.readString());
webURL.setDocid(input.readInt());
webURL.setParentDocid(input.readInt());
webURL.setParentUrl(input.readString());
webURL.setDepth(input.readShort());
webURL.setPriority(input.readByte());
webURL.setAnchor(input.readString());
webURL.setElement(input.readString());
return webURL;
}
@Override
public void objectToEntry(WebURL url, TupleOutput output) {
output.writeString(url.getURL());
output.writeInt(url.getDocid());
output.writeInt(url.getParentDocid());
output.writeString(url.getParentUrl());
output.writeShort(url.getDepth());
output.writeByte(url.getPriority());
output.writeString(url.getAnchor());
output.writeString(url.getElement());
}
}
用自定义类TupleBinding转化后即可存入DB：
DatabaseConfig dbConfig = new DatabaseConfig();
dbConfig.setAllowCreate(true);
Database urlsDB = env.openDatabase(null, dbName, dbConfig);
WebURLTupleBinding webURLBinding = new WebURLTupleBinding();
DatabaseEntry value = new DatabaseEntry();
WebURL url = new WebURL();
webURLBinding.objectToEntry(url, value);
urlsDB.put(txn, getDatabaseEntryKey(url), value);
JAVA开源爬虫crawler4j就是使用JE进行URL存储的，测过数据量在百万以下都是非常快的，百万以上也还可以接受，千万就不知道了，个人觉得到百万以上还是用非嵌入式数据库好一些！