Connect to Cloud SQL using Sql2o in Google Cloud Endpoint - google-app-engine

Question

I'm trying to connect to cloud sql inside google cloud endpoint and using lightweight jdbc wrapper sql2o as data access method.
#Api(name = "questionapi", version = "v1", description = "question api")
public class QuestionService {
private static Sql2o sql2o = new Sql2o(
"jdbc:mysql://xxx.xxx.xxx.xxx:3306/xxxxx", "root",
"xxxxxxx");
#ApiMethod(name = "get", httpMethod = HttpMethod.GET)
public List<Question> get() {
String q = "select * from questions";
try (Connection conn = sql2o.open()) {
return conn.createQuery(q).executeAndFetch(Question.class);
}
}
After the app is running, I can visit localhost:8888/_ah/api/explorer to try the api. However, there is an error says:
org.sql2o.Sql2oException: Could not acquire a connection from DataSource - No suitable driver found for jdbc:mysql://xxx.xxx.xxx.xxx:3306/xxxxx
How can I solve this issue?
EDIT:
After change to maven project and I got this new error message:
503 Service Unavailable
- Show headers -
{
"error": {
"message": "java.lang.NoClassDefFoundError: Could not initialize class com.mysql.jdbc.ConnectionImpl",
"code": 503,
"errors": [
{
"domain": "global",
"reason": "backendError",
"message": "java.lang.NoClassDefFoundError: Could not initialize class com.mysql.jdbc.ConnectionImpl"
}
]
}
}
EDIT
It's a new day, I still stuck here.
What I did is I use maven to download the endpoints-skeleton-archetype project, it's a new, empty Cloud Endpoints backend API project ready for use, with required files and directories.
I immediately deploy it to app engine, and try to return a meaningful value. It worked, a simple 'hellp world' string will be returned.
Next, I tried to connect to cloud sql using jdbc. In order to do that, I followed the tutorial here
to add <use-google-connector-j>true</use-google-connector-j> into appengine-web.xml
and I try different combination of connection string
Class.forName("com.mysql.jdbc.GoogleDriver");
String url = "jdbc:google:mysql://xxxxxxxxxxxx:xxxxx?user=root";
conn = DriverManager.getConnection(url);
ResultSet rs = conn.createStatement().executeQuery("SELECT 1 + 1");
After all these, I still get this error message.
503 Service Unavailable
- Show headers -
{
"error": {
"errors": [
{
"domain": "global",
"reason": "backendError",
"message": "java.lang.NullPointerException"
}
],
"code": 503,
"message": "java.lang.NullPointerException"
}
}

Answer 1

This error occurs when the jdbc driver is not found in the classpath. How are you managing dependencies? Do you use maven? The error should be fixed if you add the mysql jdbc driver to your list of dependencies.
I have another comment to your code, which has nothing to do with your question. But here it comes anyway.
The codeline below has a connection leak as you never closes the connection. This will eventually deplete the connection pool and your application will hang.
return sql2o.open().createQuery(q).executeAndFetch(Question.class);
This is the correct way of doing it when using sql2o:
try (Connection con = sql2o.open()) {
return con.createQuery(q).executeAndFetch(Question.class);
}