1
我寫了一個樣例MongoDB數據庫輪詢器，它連續每3秒鐘輪詢一次數據庫。每3秒鐘輪詢一次MongoDB
在查詢數據庫時，我可以每次使用相同的遊標作爲查詢，還是每次都應該獲取新遊標並相應地關閉它？
import java.net.UnknownHostException;
import java.sql.Connection;
import java.util.ArrayList;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.Mongo;
import com.mongodb.MongoURI;
public class Data extends Thread {
static DB db = getConnection("");
DBCollection table = db.getCollection("stock");
DBCursor cursor = null;
public void run() {
while (true) {
try {
ArrayList<stocks> list = new ArrayList<stocks>();
BasicDBObject searchQuery = new BasicDBObject();
table.setObjectClass(stocks.class);
cursor = table.find(searchQuery);
while (cursor.hasNext()) {
stocks s = (stocks) cursor.next();
list.add(s);
}
cursor.close();
storeOrUpdate(list);
System.out.println("*****************");
Thread.sleep(3000);
} catch (Exception e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
Data d = new Data();
d.start();
}
public static DB getConnection(String databaseName) {
if (db == null) {
System.out.println("===========================================");
String textUri = "mongodb://krn1231:[email protected]:43388/stocks";
MongoURI uri = new MongoURI(textUri);
Mongo m = null;
try {
m = new Mongo(uri);
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
db = m.getDB("stocks");
return db;
} else {
return db;
}
}
public void storeOrUpdate(ArrayList<stocks> list) throws Exception {
Connection connection = null;
connection = ConexionTest.getConnection();
for (int i = 0; i < list.size(); i++) {
stocks stoc = list.get(i);
System.out.println(stoc.get("symbol"));
}
}
}