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com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
(51 answers)
Closed 6 years ago.
I'm trying to connect to the local MySQL server but I keep getting an error.
Here is the code.
public class Connect {
public static void main(String[] args) {
Connection conn = null;
try {
String userName = "myUsername";
String password = "myPassword";
String url = "jdbc:mysql://localhost:3306/myDatabaseName";
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection(url, userName, password);
System.out.println("Database connection established");
} catch (Exception e) {
System.err.println("Cannot connect to database server");
System.err.println(e.getMessage());
e.printStackTrace();
} finally {
if (conn != null) {
try {
conn.close();
System.out.println("Database Connection Terminated");
} catch (Exception e) {}
}
}
}
}
and the errors :
Cannot connect to database server
Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:344)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2333)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2370)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2154)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at Connect.main(Connect.java:16)
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at java.net.Socket.<init>(Socket.java:375)
at java.net.Socket.<init>(Socket.java:218)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:257)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:294)
... 15 more
I've set the classpath, made sure my.cnf had the skip network option commented out.
java version is 1.2.0_26 (64 bit)
mysql 5.5.14
mysql connector 5.1.17
I made sure that the user had access to my database.
I have had the same problem in two of my programs. My error was this:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
I spent several days to solve this problem. I have tested many approaches that have been mentioned in different web sites, but non of them worked. Finally I changed my code and found out what was the problem. I'll try to tell you about different approaches and sum them up here.
While I was seeking the internet to find the solution for this error, I figured out that there are many solutions that worked for at least one person, but others say that it doesn't work for them! why there are many approaches to this error?
It seems this error can occur generally when there is a problem in connecting to the server. Maybe the problem is because of the wrong query string or too many connections to the database.
So I suggest you to try all the solutions one by one and don't give up!
Here are the solutions that I found on the internet and for each of them, there is at least on person who his problem has been solved with that solution.
Tip: For the solutions that you need to change the MySQL settings, you can refer to the following files:
Linux: /etc/mysql/my.cnf or /etc/my.cnf (depending on the Linux distribution and MySQL package used)
Windows: C:\**ProgramData**\MySQL\MySQL Server 5.6\my.ini (Notice it's ProgramData, not Program Files)
Here are the solutions:
changing bind-address attribute:
Uncomment bind-address attribute or change it to one of the following IPs:
bind-address="127.0.0.1"
or
bind-address="0.0.0.0"
commenting out "skip-networking"
If there is a skip-networking line in your MySQL config file, make it comment by adding # sign at the beginning of that line.
change "wait_timeout" and "interactive_timeout"
Add these lines to the MySQL config file:
[wait_timeout][1] = *number*
interactive_timeout = *number*
connect_timeout = *number*
Make sure Java isn't translating 'localhost' to [:::1] instead of [127.0.0.1]
Since MySQL recognizes 127.0.0.1 (IPv4) but not :::1 (IPv6)
This could be avoided by using one of two approaches:
In the connection string use 127.0.0.1 instead of localhost to avoid localhost being translated to :::1
Run java with the option -Djava.net.preferIPv4Stack=true to force java to use IPv4 instead of IPv6. On Linux, this could also be achieved by running (or placing it inside /etc/profile:
export _JAVA_OPTIONS="-Djava.net.preferIPv4Stack=true"
check Operating System proxy settings, firewalls and anti-virus programs
Make sure the Firewall, or Anti-virus software isn't blocking MySQL service.
Stop iptables temporarily on linux. If iptables are misconfigured they may allow tcp packets to be sent to mysql port, but block tcp packets from coming back on the same connection.
# Redhat enterprise and CentOS
systemctl stop iptables.service
# Other linux distros
service iptables stop
Stop anti-virus software on Windows.
change connection string
Check your query string. your connection string should be some thing like this:
dbName = "my_database";
dbUserName = "root";
dbPassword = "";
String connectionString = "jdbc:mysql://localhost/" + dbName + "?user=" + dbUserName + "&password=" + dbPassword + "&useUnicode=true&characterEncoding=UTF-8";
Make sure you don't have spaces in your string. All the connection string should be continues without any space characters.
Try to replace "localhost" with the loopback address 127.0.0.1.
Also try to add port number to your connection string, like:
String connectionString = "jdbc:mysql://localhost:3306/my_database?user=root&password=Pass&useUnicode=true&characterEncoding=UTF-8";
Usually default port for MySQL is 3306.
Don't forget to change username and password to the username and password of your MySQL server.
update your JDK driver library file
test different JDK and JREs (like JDK 6 and 7)
don't change max_allowed_packet
"max_allowed_packet" is a variable in MySQL config file that indicates the maximum packet size, not the maximum number of packets. So it will not help to solve this error.
change tomcat security
change TOMCAT6_SECURITY=yes to TOMCAT6_SECURITY=no
use validationQuery property
use validationQuery="select now()" to make sure each query has responses
AutoReconnect
Add this code to your connection string:
&autoReconnect=true&failOverReadOnly=false&maxReconnects=10
Although non of these solutions worked for me, I suggest you to try them. Because there are some people who solved their problem with following these steps.
But what solved my problem?
My problem was that I had many SELECTs on database. Each time I was creating a connection and then closing it. Although I was closing the connection every time, but the system faced with many connections and gave me that error. What I did was that I defined my connection variable as a public (or private) variable for whole class and initialized it in the constructor. Then every time I just used that connection. It solved my problem and also increased my speed dramatically.
#Conclusion#
There is no simple and unique way to solve this problem. I suggest you to think about your own situation and choose above solutions. If you take this error at the beginning of the program and you are not able to connect to the database at all, you might have problem in your connection string. But If you take this error after several successful interaction to the database, the problem might be with number of connections and you may think about changing "wait_timeout" and other MySQL settings or rewrite your code how that reduce number of connections.
If you are using MAMP PRO, the easy fix, which I really wish I had realized before I started searching the internet for days trying to figure this out. Its really this simple...
You just have to click "Allow Network Access to MySQL" from the MAMP MySQL tab.
Really, thats it.
Oh, and you MIGHT have to still change your bind address to either 0.0.0.0 or 127.0.0.1 like outlined in the posts above, but clicking that box alone will probably solve your problems if you are a MAMP user.
Setting the bind-address to the server's network IP instead of the localhost default, and setting privileges on my user worked for me.
my.cnf:
bind-address = 192.168.123.456
MySql Console:
GRANT ALL PRIVILEGES ON dbname.* to username#'%' IDENTIFIED BY 'password';
In my case,
Change the remote machine mysql configuration at /etc/mysql/my.cnf: change
bind-address = 127.0.0.1
to
#bind-address = 127.0.0.1
On the remote machine, change mysql user permissions with
GRANT ALL PRIVILEGES ON *.* TO 'user'#'%' IDENTIFIED BY 'password';
IMPORTANT: restart mysql on the remote machine: sudo /etc/init.d/mysql restart
I've just faced the same problem.
It happened because the MySQL Daemon was binded to the IP of the machine, which is required to make connection with an user that has permission to connect #your_machine.
In this case, the user should have permission to connect USER_NAME#MACHINE_NAME_OR_IP
I wanted remote access to my machine so I changed in my.cnf from
bind-address = MY_IP_ADDRESS
To
bind-address = 0.0.0.0
Which will allow an user from localhost AND even outside (in my case) to connect to the instance.
Both below permissions will work if you bind the MySQL to 0.0.0.0:
USER_NAME#MACHINE_NAME_OR_IP
USER_NAME#localhost
In my case (I am a noob), I was testing Servlet that make database connection with MySQL and one of the Exception is the one mentioned above.
It made my head swing for some seconds but I came to realize that it was because I have not started my MySQL server in localhost.
After starting the server, the problem was fixed.
So, check whether MySQL server is running properly.
In case you are having problem with a set of Docker containers, then make sure that you do not only EXPOSE the port 3306, but as well map the port from outside the container -p 3306:3306. For docker-compose.yml:
version: '2'
services:
mdb:
image: mariadb:10.1
ports:
- "3306:3306"
…
In my case it was an idle timeout, that caused the connection to be dropped on the server. The connection was kept open, but not used for a long period of time. Then a client restart works, while I believe a reconnect will work as well.
A not bad solution is to have a daemon/service to ping the connection from time to time.
As the detailed answer above says, this error can be caused by many things.
I had this problem too. My setup was Mac OSX 10.8, using a Vagrant managed VirtualBox VM of Ubuntu 12.04, with MySQL 5.5.34.
I had correctly setup port forwarding in the Vagrant config file. I could telnet to the MySQL instance both from my Mac and from within the VM. So I knew the MySQL daemon was running and reachable. But when I tried to connect over JDBC, I got the "Communications link failure" error.
In my case, the problem was solved by editing the /etc/mysql/my.cnf file. Specifically, I commented out the "#bind-address=127.0.0.1" line.
The resolution provided by Soheil was successful in my case.
To clarify, the only change I needed to make was with MySQL's server configuration;
bind-address = **INSERT-IP-HERE**
I am using an external MySQL server for my application. It is a basic Debian 7.5 installation with MySQL Server 5.5 - default configuration.
IMPORTANT:
Always backup the original of any configuration files you may modify. Always take care when elevated as super user.
File
/etc/mysql/my.cnf
Line
bind-address = 192.168.0.103 #127.0.0.1
Restart your MySQL Server service:
/usr/sbin/service mysql restart
As you can see, I simply provided the network IP of the server and commented out the default entry. Please note that simply copy and paste my solution will not work for you, unless by some miracle our hosts share the same IP.
Thanks # Soheil
I know this is an old thread but I have tried numerous things and fixed my issue using the following means..
I'm developing a cross platform app on Windows but to be used on Linux and Windows servers.
A MySQL database called "jtm" installed on both systems. For some reason, in my code I had the database name as "JTM". On Windows it worked fine, in fact on several Windows systems it flew along.
On Ubuntu I got the error above time and time again. I tested it out with the correct case in the code "jtm" and it works a treat.
Linux is obviously a lot less forgiving about case sensitivity (rightly so), whereas Windows makes allowances.
I feel a bit daft now but check everything. The error message is not the best but it does seem fixable if you persevere and get things right.
I just restarted MySQL (following a tip from here: https://stackoverflow.com/a/14238800) and it solved the issue.
I had the same issue on MacOS (10.10.2) and MySql (5.6.21) installed via homebrew.
The confusing thing was that one of my apps connected to the database fine and the other was not.
After trying many things on the app that threw the exception com.mysql.jdbc.CommunicationsException as suggested by the accepted answer of this question to no avail, I was surprised that restarting MySQL worked.
The cause of my issue might have been the following as suggested in the answer in the aforementioned link:
Are you using connection pool ? If yes, then try to restart the
server. Probably few of the connections in your connection pool are in closed state.
It happens (in my case) when there is not enough memory for MySQL. A restart fixes it, but if that's the case consider a nachine with more memory, or limit the memory taken by jvms
Go to Windows services in the control panel and start the MySQL service. For me it worked. When I was doing a Java EE project I got this error" Communication link failure". I restarted my system and then it worked.
After that I again got the same error even after restarting my system. Then I tried to open the MySQL command line console and login with root, even then it gave me an error.
Finally when I started the MySQL service from Windows services, it worked.
Had the same.
Removing port helped in my case, so I left it as jdbc:mysql://localhost/
For me the solution was to change in the conf file of mysql server the parameter bind-address="127.0.0.1" or bind-address="x.x.x.x" to bind-address="0.0.0.0".
Thanks.
If you are using hibernate, this error can be caused for keeping open a Session object more time than wait_timeout
I've documented a case in here for those who are interested.
I found the solution
since MySQL need the Localhost in-order to work.
go to /etc/network/interfaces file and make sure you have the localhost configuration set there:
auto lo
iface lo inet loopback
NOW RESTART the Networking subsystem and the MySQL Services:
sudo /etc/init.d/networking restart
sudo /etc/init.d/mysql restart
Try it now
It is majorly because of weak connection between mysql client and remote mysql server.
In my case it is because of flaky VPN connection.
In phpstorm + vagrant autoReconnect driver option helped.
I was experiencing similar problem and the solution for my case was
changing bind-address = 0.0.0.0 from 127.0.0.1
changing url's localhost to localhost:3306
the thing i felt is we should never give up, i tried every options from this post and from other forums as well...happy it works #saurab
I faced this problem also.
As Soheil suggested,
I went to php.ini file at the path C:\windows\php.ini , then I revised port number in this file.
it is on the line mysqli.default_port =..........
So I changed it in my java app as it's in the php.ini file,now it works fine with me.
For Windows :-
Goto start menu write , "MySqlserver Instance Configuration Wizard" and reconfigure your mysql server instance.
Hope it will solve your problem.
After years having the same issue and no permanent solution this is whats solved it for the past 3 weeks (which is a record in terms of error free operation)
set global wait_timeout=3600;
set global interactive_timeout=230400;
Don't forget to make this permanent if it works for you.
If you are using local emulator, you have to use IP address 10.0.2.2 instead of localhost to access to your local MySQL server.
I have build an application in java, application is one and will be used on 3 different systems,And therefore the database of that application must be online to keep all 3 applications with up to date database...
In starting I developed my application based on localhost (wampserver) and used database in "PhpMyAdmin", and hopefully application is fully developed and ready to run.. but the problem is online database connectivity!
I have uploaded my database on a Site in PhpMyAdmin and they provided below information:
and the for connecting my app to this DB is:
String url = "jdbc:mysql://fdb12.biz.nf:3306/";
String dbName = "1738412_wstore";
String driver = "com.mysql.jdbc.Driver";
String userName = "1738412_wstore";
String password = "Password";
Class.forName(driver).newInstance();
Connection conn = DriverManager.getConnection(url+dbName,userName,password);
now when I run my application it shows below error:
I dont know what the problem is there, please help me out through this..
I faced the same issue and the following helped me to solve.
http://support.hostgator.com/articles/cpanel/how-to-connect-to-the-mysql-database-remotely
Hopefully, your hosting provider should have same type of cpanel to configure MySQL database for remote connections.
Check for firewall.
Check if mysql is running.
2 things you can try:
Install MySql client locally on your machine and connect like: mysql -h fdb12.biz.nf -u 1738412_wstore -P<password>
This should work before you try anything else.
Make sure you're using the right imports in your code. See [here][1].
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
I think your DB server doesn't allow remote connections.
Try hosting in:
http://www.freesqldatabase.com/freemysqldatabase/
It's free and allow remote DB connections.
Good Luck!!!
Considering the Biz.nf FAQ:
How can I connect to my MySQL/PostgreSQL database? What settings
should I use for my script/software?
MySQL/PosgreSQL database connection can be established with script/software hosted only on your
web hosting account (meaning no remote access is allowed due to
security reasons). The following settings are needed:
So, since biz.nf does not allow remote access, it will be difficult for you to interact with their MYSQL server for your application.
The best solution and the most simple is probably to find a new provider which will allow the remote access. Heroku.com works very well.
If you really want to use the biz.nf services, it will be more difficult.
It's not a script or credential problem.
Maybe you can (probably not), try to login by SSH to configure your server to enable remote access to your MYSQL database server.
From the free plan, you will not have any access to the online SSH tool and you will need to configure your domain for a SSH connection.
In SSH, and it probably will not work considering the FAQ, you could try to simply modify your /etc/mysql/my.cnf file by commenting the bind-address line wich by default only allows local access (127.0.0.1). Then, try to restart your MYSQL service with: a simple service mysql restart to verify if the remote connection works.
If the remote connection still doesn't work after this, the only way I can find for the moment (unless you completely change your hosting provider) would be to create a kind of API hosted directly on the server and your Java program could interacts with your services (In JSON, by example).
I have a machine with CentOS and mysql server on it (let's call it 'Server'). And another(my desktop) machine with Debian (let's call it 'Desktop'). I tried to launch java program on Desktop machine. Application connects to Server's mysql database without any troubles.
When I finished development of this application (it's still works and connects to DB well) I tried to deploy this app to Server machine. I'v built it the app on the server and tried to launch, using database, which still hosted on Server machine. So now it seems to be local database for my application. But it fails during connection to DB using Server IP address or "localhost" or 127.0.0.1. I have only:
java.sql.SQLException: null, message from server: "Host '82.192.90.179' is not allowed to connect to this MySQL server".
In my.cnf file on Server I've set "bind-address=0.0.0.0".
PS:The most interesting thing, I do everything on server using ssh, and if I try to connect to database with "mysql" console tool, it connects OK either with -h82.192.90.179 and without -h option(seems to be localhost as a dafault)
To know it is permission issue try GRANT ALL ON . TO 'someuser'#%;
http://dev.mysql.com/doc/refman/4.1/en/grant.html
Then modify the above statement by replacing % with '82.192.90.179' should work.
If you feel difficult to connect JDBC means try using mysql workbench MySQL WORKBENCH
1.Make sure you have to host your server code to local server or public server
2.If you host Local Server means it will not work
3.Make sure your server is alive or not
DB_URL = "jdbc:mysql://localhost:portnumber/databasename"
eg.DB_URL = "jdbc:mysql://localhost:3306/cmes"
Maintain Your Session configuration like this in your server side in Web.xml
<session-config>
<session-timeout>-1</session-timeout>
</session-config>
I trying to test the connection with my local sql DB. I have this code:
try{
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver").newInstance();
DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=SocialFamilyTree;user=SOSCOMP");
}catch(Exception e){
System.out.println("Couldn't get database connection.");
e.printStackTrace();
}
I tried many users. my windows user is SOSCOMP and doesn't have a password. I also know that SQL 2008 create users as "sys" "dbo", I tried these too. I'm always getting:
Couldn't get database connection.
com.microsoft.sqlserver.jdbc.SQLServerException: Login failed for user 'SOSCOMP'.
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:196)
at com.microsoft.sqlserver.jdbc.TDSTokenHandler.onEOF(tdsparser.java:246)
at com.microsoft.sqlserver.jdbc.TDSParser.parse(tdsparser.java:83)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.sendLogon(SQLServerConnection.java:2532)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.logon(SQLServerConnection.java:1929)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.access$000(SQLServerConnection.java:41)
at com.microsoft.sqlserver.jdbc.SQLServerConnection$LogonCommand.doExecute(SQLServerConnection.java:1917)
at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:4026)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1416)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectHelper(SQLServerConnection.java:1061)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.login(SQLServerConnection.java:833)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.connect(SQLServerConnection.java:716)
at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect(SQLServerDriver.java:841)
at java.sql.DriverManager.getConnection(DriverManager.java:579)
at java.sql.DriverManager.getConnection(DriverManager.java:243)
at FT_Receiver.FT_Receiver.main(FT_Receiver.java:12)
Any ideas?
Thanks
If you try to connect with database which is using windows authentication, you can use 'integratedSecurity' option in your connection string.
DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=SocialFamilyTree;integratedSecurity=true;");
Having been through this very recently the steps I took to solve pretty much the same problem were
use SQL Server Management Studio to log in with the desired account and confirm access to read (and write if necessary)
Use SQL Server Configuration Manager to confirm that the server instance is listening on the IP address being targetted
Disable the firewall to check that isn't getting in the way (and add an exception if necessary for future use)
The absolute kicker for me was understanding what IP addresses and ports the instance was set to listen on so that when I constructed the connection string the connection wasn't being rejected.
Also, if you want to connect using Windows logins you need to ensure the SQL instance is configured for mixed mode authentication (i.e. to allow Windows and SQL logins)
Since you get this error,the Sql server correctly listens to the port.
Open Sql Server Management Studio connect to your Server.
right click on the server's icon and choose properties.
Go to the security tab and tick Sql Server and Windows
Authentication mode.
If you want to define a user,go from the tree, to Security->Logins,right click on logins folder and click "New Login".
Now your server should work with this Url String.
Use the log file of the Server that may help you understand its working.
Re: Did it. still WARNING: Failed to load the sqljdbc_auth.dll cause :- no sqljdbc_auth in java.library.path – Mike Oct 7 at 14:03
you have to add the path to sqljdbc_auth.dll by adding this under VM arguments in Eclipse or commandline if you're running from the shell:
-Djava.library.path="\MS SQL Server JDBC Driver 3.0\sqljdbc_3.0\enu\auth\x86"
that's if you're running 32 bit Windows. else the final subdir changes accordingly.
I think this might be a better answer though, to setting up SQL Server user based authentication:
Connecting SQL Server 2008 to Java: Login failed for user error
(I try to summarize it here: http://silveira.wikidot.com/sql-server)
I also faced the same issue, In my case the following things are configured wrongly
Two SQL (versions) servers are running in my system --> Sol: Please check ourselves which server we are pointing.
Ports are configured as dynamic --> Sol: we should set port 1433 and dynamic port should be 0, if we are connected to specific port.
While creating the new login (user) I have selected the option " change password after first login "--> Sol: we should not select this option while creating the new login, if we are trying connecting from some other service like Openfire.
I'm working on an applet uploaded to an ftp server. That applet should connect to a MySQL database (Which should be on the same server as far as I know).
Note: The applet is self signed.
If I'm running the applet locally it works fine.
If I launch the applet locally from a web browser it also works perfectly.
But when I upload it to the ftp server and launch it from it's website, it freezes at line 4 (The DriverManager.getConnection() method)
.
public static void initConnection(final Settings info) throws ClassNotFoundException, SQLException
{
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://" + info.getHost() + ":3306/" + info.getDbName(),
info.getUser(), info.getPass());
stmt = conn.createStatement();
}
It seems I have answered this myself. The problem was that from trying to connect to the database, to have a full working connection took about 3 minutes or so. Technically this question was void all along. I'll see if I can find out why it's so slow and ask another question if I can't find it.
So once again, it had nothing to do with policies or permissions. Just being slow as hell for some reason.
I think that's because, when you run the applet from the server, the Java Plug-in imposes a strict sandbox to prevent malicious actions from being performed. One of these is establishing connections to other computers.
Just write a policy file allowing connections to port 3306 of your database host (use policytool to generate it; you'll need to grant the java.net.SocketPermission permission, with the resolve and connect actions, for the DB host), then embed it into the JAR and, in the code, create a security manager using that file (here is a sample).
EDIT: I noticed from the AppletViewer log that the decryption classes you use need another permission not granted by default when the code is launched from a remote location. Follow the technique above, but grant the permission java.lang.RuntimePermission (action: accessClassInPackage.sun.misc) as well and you should be fine.