0
我有一個簡單的應用程序來偵聽UDP消息。該應用需要無限期運行。它實例通過實例，我創建它看起來像這樣的MySQLConnect對象的單個JDBC數據庫連接：在java應用程序中出現內存不足和堆棧溢出異常，無限循環
public MySQLConnect() {
this.instantiateConnection();
}
//Open the database connection. Done iniitally in
//the main class and only called again if the connection
//is closed due to an error in processing a message
public Connection instantiateConnection() {
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager
.getConnection("jdbc:mysql://localhost:3306/mydb?"
+ "user=user&password=pwd");
} catch (Exception e) {
e.printStackTrace();
}
return connection;
}
的MySQLConnect類的構造函數是從一次一個應用程序被啓動的UDPReceiver類調用。如果出現錯誤處理並且數據庫連接已關閉，則只會再次調用它。這個類看起來像：
public class UDPReceiver {
private static int port = 2140;
private static int byteSize = 1024;
private static int timeOut = 5000;
@SuppressWarnings("unused")
private static int count;
static MySQLConnect dbConnect;
public static void main(String[] args) {
recvUDPMessage();
}
public static String recvUDPMessage() {
DataTransferService dts = new DataTransferServiceImp();
dbConnect = new MySQLConnect();
try {
DatagramSocket dsocket = null;
if (dsocket == null) {
dsocket = new DatagramSocket(port);
dsocket.setBroadcast(true);
dsocket.setReuseAddress(false);
}
byte[] inbuf = new byte[byteSize];
byte[] rcvMsg;
InetAddress fromIP;
DatagramPacket receivepacket = new DatagramPacket(inbuf,
inbuf.length);
dsocket.setSoTimeout(timeOut);
//Infinitely loop and listen for UDP messages
count = 0;
boolean loopRecv = true;
while (loopRecv) {
try {
count++;
dsocket.receive(receivepacket);
// temp = receivepacket.getAddress().toString();
fromIP = receivepacket.getAddress();
String fromIPString = fromIP.toString();
rcvMsg = receivepacket.getData();
String rcvString = new String(rcvMsg, 0, rcvMsg.length);
String rcvMessage = "Message Received from: "
+ fromIPString + " Message: " + rcvString + "\n";
System.out.println(rcvMessage);
ArrayList<String> al = getMessageElements(rcvString);
//Send array of message elements to service layer
dts.saveUDPMessage(dbConnect, al, Utils.getTimeStamp());
loopRecv = true;
} catch (IOException e) {
System.out.println("Listening . . .");
loopRecv = true;
}
}
} catch (SocketException e) {
System.err.println("Sockets Exception: " + e.getMessage());
} catch (Exception e) {
System.err.println(" Exception: " + e.getMessage());
} finally {
System.out.println(". . . Close DB");
dts.closeDBConnection(dbConnect);
// I added the creation MySQLConnect object after I was getting an error that the database was closed when trying to insert.
dbConnect = new MySQLConnect();
}
return "end of routine";
}
//Extract comma delimited message elements into an array
private static ArrayList<String> getMessageElements(String rcvString) {
StringTokenizer st = new StringTokenizer(rcvString, ",");
ArrayList<String> al = new ArrayList<String>();
while (st.hasMoreElements()) {
String messageElement = (String) st.nextElement();
al.add(messageElement);
}
return al;
}
}
這將運行約8小時，然後我得到以下錯誤：在線程主java.lang.StackOverflowError的
異常
例外： java.lang.outofmemoryerror從主線程中的uncaughtexceptionhandler拋出
此前，我沒有重新實例化MySQLConnect對象的尾部呃數據庫被關閉了。問題是我收到數據庫連接已關閉的錯誤，但我的程序仍在嘗試執行jdbc插入。 jdbc插入首先檢查是否有實例化的連接，如果沒有實例化它。這從MySQLConnect類代碼如下所示：在未來的無限期和發生錯誤時寫入數據庫甚至
PreparedStatement prep = null;
if (connection == null) {
connection = this.instantiateConnection();
}
try {
prep = connection
.prepareStatement("insert into MyTable (UDPMessage)"
+ "values (?);");
prep.setString(1, udpMessage);
prep.addBatch();
prep.executeBatch();
如何建築師這個過程中要正確處理UDP消息？
另外如何解決在處理數據時發生異常時重新實例化MySQLConnect類時出現內存不足錯誤？
如果在發生異常後實例化這個類是不正確的，我該如何重新實例化與數據庫的連接以繼續處理數據？
感謝您的幫助！