Can't make JDBC connection to MySQL (using Java, IntelliJ, and Linux)

5
votes

I am having issues trying to get a database connection using the code below:

  try {
        Class.forName("com.mysql.jdbc.Driver");
        Properties p = new Properties();
        p.put("user", user_name);
        p.put("password", password);
        connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1/jsp_test", p);
    } catch (SQLException ex) {
        // handle any errors
        ex.printStackTrace();
        System.out.println("SQLException: " + ex.getMessage());
        System.out.println("SQLState: " + ex.getSQLState());
        System.out.println("VendorError: " + ex.getErrorCode());
        return false;
    } catch (ClassNotFoundException e) {
        e.printStackTrace();  
    }

The error message that is outputted is:

/usr/lib/jvm/java-6-openjdk/bin/java -Didea.launcher.port=7532 -Didea.launcher.bin.path=/usr/bin/idea/bin -Dfile.encoding=UTF-8 -classpath /usr/lib/jvm/java-6-openjdk/jre/lib/jce.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/about.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/resources.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/management-agent.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/jsse.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/charsets.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/rt.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/ext/localedata.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/ext/sunjce_provider.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/ext/sunpkcs11.jar:/usr/lib/jvm/java-6-openjdk/jre/lib/ext/dnsns.jar:/home/bedtimes/Java Projects/db_demo/out/production/db_demo:/opt/java/jre/lib/ext/mysql-connector-java-5.1.10-bin.jar:/usr/bin/idea/lib/idea_rt.jar com.intellij.rt.execution.application.AppMain Main 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:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:532) at com.mysql.jdbc.Util.handleNewInstance(Util.java:406) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2214) at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:781) at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:46) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:532) at com.mysql.jdbc.Util.handleNewInstance(Util.java:406) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:352) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:284) at java.sql.DriverManager.getConnection(DriverManager.java:620) at java.sql.DriverManager.getConnection(DriverManager.java:169) at database.Database.connect(Database.java:80) at Main.main(Main.java:13) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:110) Caused by: 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:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:532) at com.mysql.jdbc.Util.handleNewInstance(Util.java:406) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074) at com.mysql.jdbc.MysqlIO.(MysqlIO.java:343) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2137) ... 18 more Caused by: java.net.ConnectException: Connection refused at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:310) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:176) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:163) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:384) at java.net.Socket.connect(Socket.java:542) at java.net.Socket.connect(Socket.java:492) at java.net.Socket.(Socket.java:389) at java.net.Socket.(Socket.java:232) at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:253) at com.mysql.jdbc.MysqlIO.(MysqlIO.java:292) ... 19 more SQLException: 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. SQLState: 08S01 VendorError: 0

Process finished with exit code 0

I've, literally, no idea how to troubleshoot this error message. The database exists. The username and password exists. I've currently not added any tables to the database but I don't think that can be the issue, since I'm only making a connection after all...

I can provide extra information if needs be. I feel like I've tried a lot. Does anybody know any ways of getting further information on how and why it's failing?

Thanks for your help! :)

4
javamysqllinuxjdbcjar
Can you connect to it directly (using mysql client)? The only useful bit of the traceback is 08S01 and the mysql documentation mentions something about it (dev.mysql.com/doc/refman/5.0/en/…). – shylent
Have you tried using the url "jdbc:mysql://localhost/jsp_test"? Mostly just a random debug guess. – Kaleb Brasee
I can connect directly using mysql client and my username 'jsp_test'. I still can't connect if I change 127.0.0.1 to localhost. Thanks for the link, I'll take a look. I'm wondering if somebody else can try doing the same thing with their own machine and mysql-connector-java-5.1.10-bin.jar – olive

4 Answers

6
votes

From your connection string, this database should be on the local machine. Can you try running this command to ensure the socket is open for connections?

telnet 127.0.0.1 3306

and ensure that it connects? You may not have configured your mysql instance to listen for connections from this machine or on this interface address. If the connection fails, you need to modify your mysql config, for example:

http://www.cyberciti.biz/tips/how-do-i-enable-remote-access-to-mysql-database-server.html

1
votes

I had the same symptoms but for me the solution was to change the bind-address to 0.0.0.0 in /etc/mysql/my.cnf

(Just posting this for others seeking an answer to this question)

1
votes

You can try this instead:

connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/jsp_test","user_name","password");
1
votes

you can try one of the following 

"jdbc:mysql://localhost:3306/jsp_test","username","password"

or

"jdbc:mysql://'your machines ip (without quote)':3306/jsp_test","username","password"

or 

"jdbc:mysql://127.0.0.1:3306/jsp_test","username","password"

as a connection string.