问题似乎是随机的。正如您在下面的输出中所看到的，循环执行了5次（预期70次），然后出现问题。 Wait_timeout设置为28800.可能的原因是什么？ 这是代码（数据库部分）和输出。
public class DataManager {
private Connection conn=null;
private Properties props=null;
private Statement batchStat;
private ResultSet result=null;
private String userName="root";
private String password="root";
private String url="jdbc:mysql://localhost/";//jdbc:oracle:thin:@localhost";
private String driver="com.mysql.jdbc.Driver";//oracle.jdbc.OracleDriver";
public DataManager() {
try {
Class.forName(driver) ;
conn = DriverManager.getConnection(url, userName,password);
batchStat=conn.createStatement();
} catch (ClassNotFoundException ex) {
Logger.getLogger(DataManager.class.getName()).log(Level.SEVERE, null, ex);
} catch (SQLException ex) {
Logger.getLogger(DataManager.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
public ArrayList<PriceData> getPriceList(String symbol,String table,String t_date) throws SQLException{
DataManager dm=new DataManager();
ResultSet rs=dm.execute("select * from trader."+table+" where symbol = '"+symbol+"' and t_date='"+t_date+"'");
ArrayList<PriceData> priceList=new ArrayList<PriceData>();
PriceData pd=null;
while(rs.next()){
pd=new PriceData();
pd.setDate((rs.getString("t_date")));
pd.setTime((rs.getString("t_time")));
pd.setOpen(Double.parseDouble(rs.getString("open")));
pd.setHigh(Double.parseDouble(rs.getString("high")));
pd.setLow(Double.parseDouble(rs.getString("low")));
pd.setClose(Double.parseDouble(rs.getString("close")));
pd.setVolume(Long.parseLong(rs.getString("volume")));
priceList.add(pd);
}
dm.disconnect();
return priceList;
}
Output:
Total PnL for M&M : 100219.9955996275
Total PnL for MARUTI : 93443.85619986057
Total PnL for NMDC : 74072.72315007448
Total PnL for NTPC : 104440.35690015554
Total PnL for ONGC : 122273.74220007658
Jun 29, 2014 4:16:26 AM strategies.DataManager <init>
SEVERE: null
com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception:
** BEGIN NESTED EXCEPTION **
java.net.SocketException
MESSAGE: java.net.SocketException: Permission denied: connect
java.net.SocketException: java.net.SocketException: Permission denied: connect
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:151)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:280)
at com.mysql.jdbc.Connection.createNewIO(Connection.java:1765)
at com.mysql.jdbc.Connection.<init>(Connection.java:430)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:268)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at strategies.DataManager.<init>(DataManager.java:41)
at strategies.Utilities.getPriceList(Utilities.java:21)
at strategies.StratORBSpot.start(StratORBSpot.java:81)
at strategies.Starter.main(Starter.java:23)
** END NESTED EXCEPTION **
at com.mysql.jdbc.Connection.createNewIO(Connection.java:1830)
at com.mysql.jdbc.Connection.<init>(Connection.java:430)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:268)
at java.sql.DriverManager.getConnection(DriverManager.java:664)