DriverManager.getConnection() throws exception for MySql DB access

Question

I could not find a link to this issue. I have searched for examples using MySQL and I am following the examples, but I still have this issue. I am using GWT and I have set up a MySQL server on another host. I want to get things working locally before deploying. I am able to see the driver as the Class.forName("com.mysql.jdbc.Driver") call is successful. The problem is getting the connection using DriverManager.getConnection(url, username, password). I know the credentials are correct. The exception I am getting is:

java.sql.SQLException: java.lang.NoClassDefFoundError: java.net.Socket is a restricted class. Please see the Google App Engine developer's guide for more details.

Based on other examples, I do not see what I am doing differently. Could this possibly be because the SQL server is on a different host? I have set the connection string using the IP address so I don't have to do a lookup:

private static final String url="jdbc:mysql://xx.xx.xx.xx:3306/dbname";

Yes, I have a valid IP where I have the XX's. This code works fine if I am not running in the GWT. Could this be because I am running the DB server on another host? Is this not allowed?

Help is appreciated

Marty

Marty, are you doing the JDBC/Hibernate/whatever calls somewhere on the server side? Be sure that you do not try to call from clientside. Maybe you could share more settings like your query-code... — Jaques le Fraque
– Jaques le Fraque, Commented Mar 3, 2012 at 18:42
No, I am simply trying to connect to the database to do a query. This should only require the Class.forName() call and a connect call. Since I posted this, I am now using DriverManager.registerDriver(newAppEngineDriver()); With this call I can access the online SQL database, but still get the socket error with the local database. You asked me to share the query code, I have not gotten there yet, I have to connect before I can do a query. — Marty
– Marty, Commented Mar 3, 2012 at 23:44

Community · Accepted Answer · 2017-05-23 10:34:51Z

1

Your code is running on Google App Engine. You aren't allowed to use MySQL on GAE.

See Can I use a MySQL database with an App Engine application

edited May 23, 2017 at 10:34

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answered Mar 4, 2012 at 16:20

checketts

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2 Comments

Marty Over a year ago

Under settings for App Engine there is a section on Google Cloud SQL. Under there you can choose to "Use MySQL instance" for development, which is what I am trying to do. Are you saying that for development you cannot use a local database?

checketts Over a year ago

I believe you have to use Google's specific MySQL. Note the requirement to 'create a Google cloud sql instance' section: developers.google.com/cloud-sql/docs/before_you_begin

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