Connection does not throw error but does not succeed either

问题

I am currently trying to connect to an amazon RDS from a lambda function. The problem I am facing is that I do not get an error but neither I manage to get a connection, so I am not sure how to proceed. I do not have a timeout, or an error with the parameters, but the object "con" is always null.

To do this I am doing the following:

Connection con = null;
String jdbcUrl2 = "jdbc:mysql://" + "connectionValueExample-zone.rds.amazonaws.com" + ":" + "3306" + "/" + "botdb" + "?user=" + "bot" + "&password=" + "PWvalueExample";
con = DriverManager.getConnection(jdbcUrl2);

After every step I check with prints() how it's going. After I try to stablish the connection I try to catch it, because while I am not getting exceptions right now, the object con never stops being null, so I do not stablish a connection.

catch (SQLException e) { 
        e.toString();
        log.warn(e.toString());
    }catch (Exception e) {
        System.out.println("excepcion no capturada ");
        e.toString();               
    }

The second catch is just in case I was missing something, originally it was not there.

All in all, the code looks something like:

@Override
public String handleRequest(Object input, Context context) {
    context.getLogger().log("Input: " + input);
Connection con = null;
    try {
        String jdbcUrl2 = "jdbc:mysql://" + "value-zone.rds.amazonaws.com" + ":" + "3306" + "/" + "botdb" + "?user=" + "bot" + "&password=" + "PW";
        con = DriverManager.getConnection(jdbcUrl2);
    }
    catch (SQLException e) { 
        e.toString();
        log.warn(e.toString());
    }catch (Exception e) {
        System.out.println("excepcion no capturada ");
        e.toString();               
    }
    String status = null;
    if (con != null) {
        status = "conexion establecida";
        System.out.println("connection stablished");
    }else status = "connection failed";
    return status; 
}

Edit:

I am now capturing slightly better the exceptions and get the following message:

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 this point I am unsure if the Strin jdbcURL is not properly formed OR why is the connection failing.

来源：https://stackoverflow.com/questions/49012188/connection-does-not-throw-error-but-does-not-succeed-either

标签

java

jdbc

aws-lambda