We Keep Coding

Connection problem while connecting to PostgreSQL database through JDBC

I have an IP address 192.168.218.18
I've tried a lot of ways connecting to that server every time I'm getting a message as connection attempt failed.
For security reasons I've hidden the username and password.
Code:
public static void main(String[] args) {
String url = "jdbc:postgresql://192.168.218.18:5432/manikanta?user=*****&password=*****&ssl=true";
try {
Connection conn = DriverManager.getConnection(url);
System.out.println("connection established");
} catch (SQLException e) {
System.out.println(e.getMessage());
}
}
}
Exceptions i got
org.postgresql.util.PSQLException: The connection attempt failed. at
org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:292)
at
org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:49)
at org.postgresql.jdbc.PgConnection.(PgConnection.java:211) at
org.postgresql.Driver.makeConnection(Driver.java:458) at
org.postgresql.Driver.connect(Driver.java:260) at
java.sql.DriverManager.getConnection(Unknown Source) at
java.sql.DriverManager.getConnection(Unknown Source) at
com.inno.demo.ConnectionJDBC.main(ConnectionJDBC.java:17) Caused by:
java.net.SocketTimeoutException: connect timed out at
java.net.DualStackPlainSocketImpl.waitForConnect(Native Method) at
java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source) at
java.net.AbstractPlainSocketImpl.doConnect(Unknown Source) at
java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source) at
java.net.AbstractPlainSocketImpl.connect(Unknown Source) at
java.net.PlainSocketImpl.connect(Unknown Source) at
java.net.SocksSocketImpl.connect(Unknown Source) at
java.net.Socket.connect(Unknown Source) at
org.postgresql.core.PGStream.(PGStream.java:75) at
org.postgresql.core.v3.ConnectionFactoryImpl.tryConnect(ConnectionFactoryImpl.java:91)
at
org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:192)
... 7 more

You should be passing the user and password separately, not as part of the URL:
public static void main(String[] args) {
String url = "jdbc:postgresql://192.168.218.18:5432/v";
String user = "****";
String password = "*****";
try (Connection con = DriverManager.getConnection(url, user, password);
System.out.println("connection established");
} catch (SQLException e) {
System.out.println(e.getMessage());
}
}
See: http://zetcode.com/java/postgresql/

Since pinging to the IP 192.168.218.18 (I'll refer to this as target system) has failed, verify and confirm one of the following:
Your system is connected to the same network as the target system (i.e. Private network)
If you have access to the target system, try pinging your local machine's IP from that system and check if pinging is successful from there or not
Make sure that your/target system's firewall is configured to allow connections to each other
If you confirm these, I am sure you will at least have a basic idea of what and where it is going wrong. And with that your connection issue will get resolved.

Connecting MSAccess database with java webapplication

I am trying to connect Msaccess database with my java webapplication using the following code:
import java.sql.*;
public class connection {
public static void main(String[] args) {
try {
// Load MS accces driver class
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
System.out.println("loaded");
String url = "jdbc:odbc:OnboardingTT";
System.out.println("assigned");
// specify url, username, pasword - make sure these are valid
Connection conn = DriverManager.getConnection(url,"","");
System.out.println("Connection Succesfull");
} catch (Exception e) {
System.err.println("Got an exception! ");
System.err.println(e.getMessage());
}}}
But connection is not established. and the error is
loaded
assigned
Got an exception!
null
java.lang.NullPointerException
at sun.jdbc.odbc.JdbcOdbcDriver.initialize(Unknown Source) at
sun.jdbc.odbc.JdbcOdbcDriver.connect(Unknown Source) at
java.sql.DriverManager.getConnection(Unknown Source) at
java.sql.DriverManager.getConnection(Unknown Source) at
connect.connection.main(connection.java:18)
I also tried with
String url = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb,*.accdb)};DBQ="+ "C:\\OnboardingTT.mdb";
Is this code correct or i have to do any changes in this please answer my question

Looks like something went wrong with the DB connection, maybe the DB is not online, maybe the user or the password are incorrect...
Please provide more info to help us to help you.
;-)

HSQL Connection Error. Any insight?

I'm trying to connect to HSQL using java. I'm using a tutorial to work with JDBC and hibernate. It's the lynda tutorials. Anyway, here's the code below:
package com.lynda.javatraining.db;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class Main {
private static final String USERNAME = "dbuser";
private static final String PASSWORD = "dbpassword";
private static final String CONN_STRING =
"jdbc:hsqldb://data/explorecalifornia";
public static void main(String[] args) throws SQLException {
//Class.forName("com.mysql.jdbc.Driver");
Connection conn = null;
System.out.println("A");
System.out.println(conn == null);
System.out.println(CONN_STRING);
try {
System.out.println("B1");
conn = DriverManager.getConnection(CONN_STRING, USERNAME, PASSWORD);
System.out.println("B1-2");
System.out.println("Connected!");
} catch (SQLException e) {
System.out.println("B2");
System.err.println(e);
} finally {
System.out.println("B3");
if (conn != null) {
conn.close();
}
}
System.out.println("C");
}
}
Here's the error I'm getting:
A
true
jdbc:hsqldb://data/explorecalifornia
B1
2014-06-27T15:26:27.430-0400 SEVERE could not reopen database
org.hsqldb.HsqlException: Database lock acquisition failure: lockFile: org.hsqldb.persist.LockFile#76d682a[file =/data/explorecalifornia.lck, exists=false, locked=false, valid=false, ] method: openRAF reason: java.io.FileNotFoundException: /data/explorecalifornia.lck (No such file or directory)
at org.hsqldb.error.Error.error(Unknown Source)
at org.hsqldb.error.Error.error(Unknown Source)
at org.hsqldb.persist.LockFile.newLockFileLock(Unknown Source)
at org.hsqldb.persist.Logger.acquireLock(Unknown Source)
at org.hsqldb.persist.Logger.openPersistence(Unknown Source)
at org.hsqldb.Database.reopen(Unknown Source)
at org.hsqldb.Database.open(Unknown Source)
at org.hsqldb.DatabaseManager.getDatabase(Unknown Source)
at org.hsqldb.DatabaseManager.newSession(Unknown Source)
at org.hsqldb.jdbc.JDBCConnection.<init>(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.getConnection(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:571)
at java.sql.DriverManager.getConnection(DriverManager.java:215)
at com.lynda.javatraining.db.Main.main(Main.java:24)
B2
java.sql.SQLException: Database lock acquisition failure: lockFile: org.hsqldb.persist.LockFile#76d682a[file =/data/explorecalifornia.lck, exists=false, locked=false, valid=false, ] method: openRAF reason: java.io.FileNotFoundException: /data/explorecalifornia.lck (No such file or directory)
B3
C
Can anyone tell e what I"m doing wrong? Thanks.

A database has a lock file explorecalifornia.lck that prevents communication. You should delete lock file and restart the database. This may happens from time to time when you accidentally shutdown the database or system.
See the syntax of the command used from the command line to invoke shutdown. There's also an option how to shutdown server in Java.

Java SQl Server connection error

I have written sql server connection part.When I run this code, i got this error.
Error Trace in getConnection() : com.microsoft.jdbc.sqlserver.SQLServerDriver
Error: No active Connection
java.lang.ClassNotFoundException: com.microsoft.jdbc.sqlserver.SQLServerDriver
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at com.sample.DB.getConnection(DB.java:30)
at com.sample.DB.displayDbProperties(DB.java:49)
at com.sample.DB.main(DB.java:85)
I have installed sql sever 2008 R2. I serached google I couldn't find the solution....
This is my code
public class DB {
private java.sql.Connection con = null;
private final String url = "jdbc:microsoft:sqlserver://";
private final String serverName= "localhost";
private final String portNumber = "1433";
private final String databaseName= "XONTHOMass_User";
private final String userName = "sa";
private final String password = "xont#123";
// Informs the driver to use server a side-cursor,
// which permits more than one active statement
// on a connection.
private final String selectMethod = "cursor";
private String getConnectionUrl(){
return url+serverName+":"+portNumber+";databaseName="+databaseName+";selectMethod="+selectMethod+";";
}
private java.sql.Connection getConnection(){
try{
System.out.println("========1========");
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
System.out.println("==== 2=====");
con = java.sql.DriverManager.getConnection(getConnectionUrl(),userName,password);
if(con!=null) System.out.println("Connection Successful!");
}catch(Exception e){
e.printStackTrace();
System.out.println("Error Trace in getConnection() : " + e.getMessage());
}
return con;
}
/*
Display the driver properties, database details
*/
public void displayDbProperties(){
java.sql.DatabaseMetaData dm = null;
java.sql.ResultSet rs = null;
try{
con= this.getConnection();
if(con!=null){
dm = con.getMetaData();
System.out.println("Driver Information");
System.out.println("\tDriver Name: "+ dm.getDriverName());
System.out.println("\tDriver Version: "+ dm.getDriverVersion ());
System.out.println("\nDatabase Information ");
System.out.println("\tDatabase Name: "+ dm.getDatabaseProductName());
System.out.println("\tDatabase Version: "+ dm.getDatabaseProductVersion());
System.out.println("Avalilable Catalogs ");
rs = dm.getCatalogs();
while(rs.next()){
System.out.println("\tcatalog: "+ rs.getString(1));
}
rs.close();
rs = null;
closeConnection();
}else System.out.println("Error: No active Connection");
}catch(Exception e){
e.printStackTrace();
}
dm=null;
}
private void closeConnection(){
try{
if(con!=null)
con.close();
con=null;
}catch(Exception e){
e.printStackTrace();
}
}
public static void main(String[] args) throws Exception
{
DB myDbTest = new DB();
myDbTest.displayDbProperties();
}
}
Please help me..I did this application using the eclipse.I have put jar file also `sqljdbc4.jar'...
Please help me

You receive the exception:
java.lang.ClassNotFoundException: com.microsoft.jdbc.sqlserver.SQLServerDriver
That means your program cannot find the Driver and therefore not even try to connect to the database.
Mircosoft has an article on How to Get Started with Microsoft JDBC:
The Microsoft SQL Server 2000 driver for JDBC .jar files must be listed in your CLASSPATH variable. The CLASSPATH variable is the search string that Java Virtual Machine (JVM) uses to locate the JDBC drivers on your computer..

As a complete guess, you have installed Express Edition (you should always mention the edition, not just the version) but you have not enabled TCP/IP support using the SQL Server Configuration Manager. By default, Express Edition does not have any network protocols enabled, so connecting over TCP/IP will not work unless you enable it first.

I think this is the driver that you need to use
com.microsoft.sqlserver.jdbc.SQLServerDriver
not com.microsoft.jdbc.sqlserver.SQLServerDriver

Just do one thing go to http://www.java2s.com/Code/Jar/s/Downloadsqljdbcjar.htm and download the sqljdbc jar and use it in your program.

Java RMI cannot connect to host from external client

I've been using RMI in this project for a while. I've gotten the client program to connect (amongst other things) to the server when running it over my LAN, however when running it over the internet I'm running into the following exception:
java.rmi.ConnectException: Connection refused to host: (private IP of host machine); nested exception is:
java.net.ConnectException: Connection timed out: connect
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(Unknown Source)
at sun.rmi.transport.tcp.TCPChannel.createConnection(Unknown Source)
at sun.rmi.transport.tcp.TCPChannel.newConnection(Unknown Source)
at sun.rmi.server.UnicastRef.invoke(Unknown Source)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Unknown Source)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(Unknown Source)
at $Proxy1.ping(Unknown Source)
at client.Launcher$PingLabel.runPing(Launcher.java:366)
at client.Launcher$PingLabel.<init>(Launcher.java:353)
at client.Launcher.setupContentPane(Launcher.java:112)
at client.Launcher.<init>(Launcher.java:99)
at client.Launcher.main(Launcher.java:59)
Caused by: java.net.ConnectException: Connection timed out: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(Unknown Source)
at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(Unknown Source)
... 12 more
This error is remeniscent of my early implementation of RMI and I can obtain the error verbatum if I run the client locally without the server program running as well. To me Connection Timed Out means a problem with the server's response.
Here's the client initiation:
public static void main(String[] args)
{
try
{
String host = "<WAN IP>";
Registry registry = LocateRegistry.getRegistry(host, 1099);
Login lstub = (Login) registry.lookup("Login Server");
Information istub = (Information) registry.lookup("Game Server");
new Launcher(istub, lstub);
}
catch (RemoteException e)
{
System.err.println("Client exception: " + e.toString());
e.printStackTrace();
}
catch (NotBoundException e)
{
System.err.println("Client exception: " + e.toString());
e.printStackTrace();
}
}
Interestingly enough no Remote Exception is thrown here.
Here's the server initiation:
public static void main(String args[])
{
try
{
GameServer gobj = new GameServer();
Information gstub = (Information) UnicastRemoteObject.exportObject(
gobj, 1099);
Registry registry = LocateRegistry.createRegistry(1099);
registry.bind("Game Server", gstub);
LoginServer lobj = new LoginServer(gobj);
Login lstub = (Login) UnicastRemoteObject.exportObject(lobj, 7099);
// Bind the remote object's stub in the registry
registry.bind("Login Server", lstub);
System.out.println("Server ready");
}
catch (Exception e)
{
System.err.println("Server exception: " + e.toString());
e.printStackTrace();
}
}
Bad practice with the catch(Exception e) I know but bear with me.
Up to this stage I know it works fine over the LAN, here's where the exception occurs over the WAN and is the first place a method in the server is called:
private class PingLabel extends JLabel
{
private static final long serialVersionUID = 1L;
public PingLabel()
{
super("");
runPing();
}
public void setText(String text)
{
super.setText("Ping: " + text + "ms");
}
public void runPing()
{
try
{
PingThread pt = new PingThread();
gameServer.ping();
pt.setRecieved(true);
setText("" + pt.getTime());
}
catch (RemoteException e)
{
e.printStackTrace();
}
}
}
That's a label placed on the launcher as a ping test. the method ping(), in gameserver does nothing, as in is a null method.
It's worth noting also that ports 1099 and 7099 are forwarded to the server machine (which should be obvious from the stack trace).
Can anyone see anyting I'm missing/doing wrong? If you need any more information just ask.
EDIT: I'm practically certain the problem has nothing to do with my router settings. When disabling my port forwarding settings I get a slightly different error:
Client exception: java.rmi.ConnectException: Connection refused to host: (-WAN IP NOT LOCAL IP-);
but it appears both on the machine locally connected to the server and on the remote machine.
In addition, I got it to work seamlessly when connecting the server straight tho the modem (cutting out the router. I can only conclude the problem is in my router's settings but can't see where (I've checked and double checked the port forwarding page). That's the only answer i can come up with.

Are you using NAT (Network Address Translation)? This is the typical case if your LAN uses non-routable address behind a router (like 10.x or 192.169.x etc).
If this is the case, you need to specify the public IP of the server with following option,
-Djava.rmi.server.hostname=host_name_or_public_ip