If I do this:
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/imageusers?autoReconnect=true&useSSL=false&relaxAutoCommit=true", "username", "password");
then it works perfectly fine but if I do this:
Connection myConn = DriverManager.getConnection("jdbc:mysql://IP:3306/imageusers?autoReconnect=true&useSSL=false&relaxAutoCommit=true", "username", "password");
Then it gives me a long list of errors:
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
I got my IP address from this website: http://whatismyipaddress.com/
and double checked it on another finder and it was the same so I don't think I'm putting in the IP address wrong. I also have made an exception for the port 3306 in windows firewall and have checked to see if MySQL was running in the services application in windows and it was. I had the MySQL program thing open and running as well. I don't know what else to do.
What you are giving here is public IP. It won't convert it to a private ip address. Try pinging to the public IP from the machine you are connecting to the DB server. It also won't work. I suggest you using a private ip address.
Related
I'm writing a program to push stuff into a remote database. My database is stored on a redhat server, while my program is written on a windows machine.
I dont want to give out my server addresses but lets say my Linux server is xx.xx.xx.xx8
MySQL Workbench in windows says that my mysql server host is 127.0.0.1:3306
I know there are a million similar questions but each one is pretty unique to the situation.
I've been using http://www.vogella.com/tutorials/MySQLJava/article.html#javaconnection as a guide but this looks like a local connection.
I have also been referencing this but it confuses me.
Here's a mock up of some code i think may work:
Connection connection = null;
String dburl = "jdbc:mysql://127.0.0.1:3306/Db_Name";
String userName = "user";
String passWord = "password";
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(dburl, userName, passWord);
Statement st = connection.createStatement();
String query = "INSERT INTO Example (`TestColumn`) VALUES('hello')";
int rsI = st.executeUpdate(query);
System.out.println("Hi");
}catch (Exception e) {
System.out.println(e);
} finally {
if (connection != null) {
try {
connection.close();
System.out.println("Database connection terminated");
} catch (Exception e) { /* ignore close errors */ }
}
}
that is based on the link i provided. All i changed was the address. I have no idea where the server address xx.xx.xx.xx8 should go.
In order to connect to the remote database you need to know the external ( or called public ) ip address of the server.
String dburl = "jdbc:mysql://85.65.85.222:3306/Db_Name"
Even if your database on server says it listens on localhost:3306, you can still connect to it using public ip with correct port. (providing you have sufficient access rights to the server)
Sometimes there may be situation that even if you know the remote server IP address you still won't be able to connect to remote database directly perhaps due to blocked port or other ACL issues ( and this is ofc applicable if you have no control over this). You could however create ssh tunnel to that server and create a port forward.
JSch jsch = new JSch();
Session session = jsch.getSession(user, host);
session.setPassword(password);
session.connect(timeout);
session.setPortForwardingL(listenPort, destHost, destPort);
example ssh connnection could look something like this:
ssh user#85.65.85.222 -Llocalhost:5050:127.0.0.1:3306 <- this will create a ssh tunnel with port forwarding, meaning on your local machine where you have your code and whole environment you will still be able to connect to remote database using
String dburl = "jdbc:mysql://localhost:5050/dbname"
Just to clarify for anyone looking at this later...
localhost is always the machine you are sitting at - always. There is no way you will ever connect to a remote box using localhost. Also, the IP address 127.0.0.1 is equivalent to localhost, so don't use that either.
You may see that the database binds to localhost or 127.0.0.1 on the database server. That is ok. Use the IP address of the server running the database in your database connection URL
mysql:jdbc://<IPOfServer>:<PortOfServer>/<DbName>).
You can find the IP address of the server by running the following command on the database server...
Windows: ipconfig
Linux: ifconfig
Good luck!
You can see what documentation says:
The method DriverManager.getConnection establishes a database
connection. This method requires a database URL, which varies
depending on your DBMS. The following are some examples of database
URLs:
MySQL: jdbc:mysql://localhost:3306/, where localhost is the name of
the server hosting your database, and 3306 is the port number
So, for MySQL Connector/J Database URL
The following is the database connection URL syntax for MySQL Connector/J:
jdbc:mysql://[host][,failoverhost...]
[:port]/[database]
[?propertyName1][=propertyValue1]
[&propertyName2][=propertyValue2]...
Where:
host:port is the host name and port number of the computer hosting your database. If not specified, the default values of host and port are 127.0.0.1 and 3306, respectively. So, every operation you do will be applied on this post
database is the name of the database to connect to. If not specified, a connection is made with no default database.
failover is the name of a standby database (MySQL Connector/J supports failover).
propertyName=propertyValue represents an optional, ampersand-separated list of properties. These attributes enable you to instruct MySQL Connector/J to perform various tasks.
Update: if you have a remote databases (your remote server) that you want to access to, you should have for example:
String dburl = "jdbc:mysql://<REMOTE_HOST>:3306/Db_Name"; //replace with your remote host
... // here all the code related to your remote host
Note: if you remote server has in its configuration "localhost" you have to figure out its public ip address by executing ifconfig. Then use its ip address on your string. As important note your remote server must be configured to allow remote connections.
if you connect to a server (ie. with the ip xx.xx.xx.xx8) you specify through the port (which is usually 3306) that you want to connect to the databaseserver on that machine. so simply use:
String dburl = "jdbc:mysql://xx.xx.xx.xx8:3306/Db_Name";
as your connectionstring.
If you dont know the port, mysql is running, have a look in your /etc/mysql/my.cnf file. There should be the port specified.
Also have a look at your firewallrules if you can't connect and make sure you enabled remoteconnections (here is a good tutorial to enable it: http://www.cyberciti.biz/tips/how-do-i-enable-remote-access-to-mysql-database-server.html).
Could someone help me with establishing connection with my DB on non-localhost server?
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://"+SERVER+"/javadb?user=javadb&password=*****");
How could I set-up the SERVER String for my domain www.lmntstudio.cz?
All required files are stored in one folder on the server.
I did it first on my localhost server and everything works well. But with the connection to another server is trouble.
I would recommend not to open MySQL connection from the client/user machine to the server. Because this would make your DB server open and prone to attacks.
Rather consider using web service. call that web service from your JWS application from client side and get the data.
Another point to consider is that opening a connection on a port say 3360 may be blocked by the firewall. If my firewall is set to block any out bound connection on port 3306 the connection could not be established.
Please ensure the MySQL is running in default port 3306 else you need change the port number accordingly.
Connection connection = DriverManager.getConnection(
"jdbc:mysql://www.lmntstudio.cz:3306/javadb", "username", "password");
instead of www.lmntstudio.cz you can use ip of the domain.
run the following in the command line to get the ip
cmd prompt> nslookup www.lmntstudio.cz
The Url syntax as follows
jdbc:mysql://(host/ip):port/databasename", "username", "password"
My server's code looks like:
Registry r = java.rmi.registry.LocateRegistry.createRegistry(1399);
r.rebind("Chat", new IRC());
and my client's code is
IRCInterface remoteObject = (IRCInterface) Naming.lookup("rmi://localhost:1399/Chat");
String history = remoteObject.read();
on the localhost it works correctly, but I can't connect two remote computers (hosts).
I've turned off all firewalls.
What's wrong?
The console outputs:
Error: java.rmi.ConnectException: Connection refused to host: 150.254.79.20; nested exception is:
java.net.ConnectException: Connection timed out: connect
Naming.lookup("rmi://localhost:1399/Chat");
localhost in above lookup should be replaced with remotehost IP (or) machine name. Otherwise lookup happens on only local machine.
When trying to connect with a remote Oracle database via JDBC I receive the following exception:
java.sql.SQLRecoverableException: IO-fout: The Network Adapter could not establish the connection
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:419)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:536)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:228)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:521)
at java.sql.DriverManager.getConnection(DriverManager.java:322)
at java.sql.DriverManager.getConnection(DriverManager.java:358)
The following is my set-up:
Database: Oracle 10g Release 2 Standard Edition
JDBC library: ojdbc6.jar
JDBC driver: oracle.jdbc.driver.OracleDriver
JDBC URL: jdbc:oracle:thin:#9.2.2.2:1521:ORCL where ORCL is database's SID
JDBC User/pwd: Correct username / password
Strange about this problem is that the connection works just fine when I work from work. When I try to connect however from home via an AT&T VPN connection, it doesn't work.
I have confirmed that I can reach the IP address and have also telnetted the ip on port 1521, which works just fine. Connecting to the datasource from a local WebLogic Application Server also works alright. Furthermore, when trying to connect to the database via sqldeveloper I can also reach the database.
I need to reach the database however from a standalone application (for testing purposes). Does anyone have an idea why this problem occurs? And whether there are alternatives for connecting to a remote Oracle Database, alternatives which sqldeveloper and weblogic perhaps use?
Here's an excerpt of the code attempting to connect with the database:
public static void main(String args[]) throws ClassNotFoundException, SQLException {
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:#9.2.2.2:1521:ORCL", "user", "pwd");
}
When a client connects to an Oracle server, it first connnects to the Oracle listener service. It often redirects the client to another port. So the client has to open another connection on a different port, which is blocked by the firewall.
So you might in fact have encountered a firewall problem due to Oracle port redirection. It should be possible to diagnose it with a network monitor on the client machine or with the firewall management software on the firewall.
If it is on a Linux box, I would suggest you add the database IP name and IP resolution to the /etc/hosts.
I have the same error and when we do the above, it works fine.
Take a look at this post on Java Ranch:
http://www.coderanch.com/t/300287/JDBC/java/Io-Exception-Network-Adapter-could
"The solution for my "Io exception: The Network Adapter could not establish the connection" exception was to replace the IP of the database server to the DNS name."
I had similar problem before. But this was resolved when I started using hostname instead of IP address in my connection string.
I have a java program that connects to a MS SQL database. The program works perfectly when running through eclipse however I get an error when I run it through AIX:
java.sql.SQLException: Network error IOException: A remote host refused an attempted connect operation.
I can successfully ping the server but am not able to telnet into the server. I am also not able to telnet from my windows desktop.
I am using jtds to connect:
String connectionString = "jdbc:jtds:sqlserver://"+dropez_ip_address+"/"+dropez_db_name;
ResultSet rs = null;
Statement stmt = null;
try{
Class.forName("net.sourceforge.jtds.jdbc.Driver");
Connection conn = DriverManager.getConnection(connectionString, dropez_db_username, dropez_db_password);
stmt = conn.createStatement();
}catch(Exception e){}
Here is some documentation from jTDS regarding the issue, but I am still not able to resolve the issue.
Why do I get java.sql.SQLException: "Network error IOException: Connection refused: connect" when trying to get a connection?
The "Connection refused" exception is thrown by jTDS when it is unable to connect to the server. There may be a number of reasons why this could happen:
- The server name is misspelled or the port number is incorrect.
- SQL Server is not configured to use TCP/IP. Either enable TCP/IP from SQL Server's Network Utility app or have jTDS connect via named pipes (see the URL format for information on how to do this).
- There is a firewall blocking port 1433 on the server.
To check whether TCP/IP is enabled and the port is not blocked you can use "telnet 1433". Until telnet doesn't connect, jTDS won't either. If you can't figure out why, ask your network administrator for help.
If you can't telnet on port 1433, you are blocked by a firewall somewhere in the middle between your machine and the server. That's not a java related problem.
May it be that when you say "it runs perfectly under eclipse but not AIX" you are taking about 2 different computers ? If so, the one with eclipse is not firewalled, the one where you deploy your app is blocked.
But again, nothing to do with java. It's a level 3 error (TCP layer) of TCP-IP model.
Regards,
Stéphane
Your SQL Server database probably doesn't have the TCP/IP protocol enabled, to enable it:
From the Microsoft SQL Server 2005 -> Configuration Tools, open the 'Microsoft SQL Server Configuration Manager'.
Expand ‘SQL Server 2005 Network Configuration’, and then click ‘Protocols for ’.
Right-click ‘TCP/IP’ and then click ‘Enable’. The icon for the protocol will change to show that the protocol is enabled.
For SQL Server 2008: