Reference a mysql table from java code

veryangryman

I have a mysql database called "bars" on my local PC that i can get to with the following address in my browser.

http://localhost/phpmyadmin/db_structure.php?db=bars#PMAURL-0:db_structure.php?db=bars&table=&server=1&target=&token=dc9eefce21adff97525fbf0feb8ccf3e


However, i don't know how to code the address of it in the Java code to set up connection. What should be in the below?

static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost/bars";

TrueDub

veryangryman wrote: »

I have a mysql database called "bars" on my local PC that i can get to with the following address in my browser.

http://localhost/phpmyadmin/db_structure.php?db=bars#PMAURL-0:db_structure.php?db=bars&table=&server=1&target=&token=dc9eefce21adff97525fbf0feb8ccf3e


However, i don't know how to code the address of it in the Java code to set up connection. What should be in the below?

static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost/bars";

you're missing the port number, which is probably 3306, assuming you installed MySQL with the default options.

So your URL should be jdbc:mysql://localhost:3306/bars

veryangryman

Thanks i think thats correct - however there is mention of StrictMode below. I think this needs to be disabled before it will work but im not sure how

01-08 16:00:49.159 2916-2916/com.example.erayfra.myapplication W/System.err﹕ [ 01-08 16:00:49.159 2916: 2916 W/System.err ]
android.os.NetworkOnMainThreadException
01-08 16:00:49.159 2916-2916/com.example.user.myapplication W/System.err﹕ at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147)

Colonel Panic

NetworkOnMainThreadException is the thing to Google here. It's considered bad practice to do work on the UI thread as it makes applications unresponsive. It looks like Android goes out of it's way to throw an exception if you try.

veryangryman

Sort of got around this but connection refused. I know this is running on port 3307 and i know the user and password is ok


mysql> status

---

C:\Program Files\MySQL\MySQL Server 5.6\bin\mysql.exe Ver 14.14 Distrib 5.6.21, for Win64 (x86_64)

Connection id: 15
Current database:
Current user: root@localhost
SSL: Not in use
Using delimiter: ;
Server version: 5.6.21-log MySQL Community Server (GPL)
Protocol version: 10
Connection: Shared memory: MYSQL
Server characterset: utf8
Db characterset: utf8
Client characterset: utf8
Conn. characterset: utf8
TCP port: 3307
Uptime: 19 hours 2 min 57 sec


But still get done by exception

01-09 11:50:41.611 1913-1913/com.example.user.myapplication W/System.err﹕ java.sql.SQLException: Server connection failure during transaction. Due to underlying exception: 'java.net.SocketException: java.net.ConnectException: failed to connect to localhost/127.0.0.1 (port 3307): connect failed: ECONNREFUSED (Connection refused)'.

h57xiucj2z946q

veryangryman wrote: »

Sort of got around this but connection refused. I know this is running on port 3307 and i know the user and password is ok


mysql> status

---

C:\Program Files\MySQL\MySQL Server 5.6\bin\mysql.exe Ver 14.14 Distrib 5.6.21, for Win64 (x86_64)

Connection id: 15
Current database:
Current user: root@localhost
SSL: Not in use
Using delimiter: ;
Server version: 5.6.21-log MySQL Community Server (GPL)
Protocol version: 10
Connection: Shared memory: MYSQL
Server characterset: utf8
Db characterset: utf8
Client characterset: utf8
Conn. characterset: utf8
TCP port: 3307
Uptime: 19 hours 2 min 57 sec


But still get done by exception

01-09 11:50:41.611 1913-1913/com.example.user.myapplication W/System.err﹕ java.sql.SQLException: Server connection failure during transaction. Due to underlying exception: 'java.net.SocketException: java.net.ConnectException: failed to connect to localhost/127.0.0.1 (port 3307): connect failed: ECONNREFUSED (Connection refused)'.

Your android app is trying to connect to localhost:3307 ? You have MySql on your laptop!

veryangryman

Rebecca Careful Sequel wrote: »

Your android app is trying to connect to localhost:3307 ? You have MySql on your laptop!

Sorry to sound silly but im not following. I do have mysql running on laptop yes.

Colonel Panic

So the Android app is using the wrong hostname.

EamonnDunne

What others are pointing out is that localhost is only accessible from the local machine, the laptop. Android can't access it using that name. It needs an IP address or hostname.

Just also want to point out that having Android connect directly the database is very bad practice, ideally you should be exposing the database using a REST webservice. Regarding doing operations on the main thread which as you have seen is not allowed. You need to learn about AsyncTask developer.android.com/reference/android/os/AsyncTask.html

veryangryman

EamonnDunne wrote: »

What others are pointing out is that localhost is only accessible from the local machine, the laptop. Android can't access it using that name. It needs an IP address or hostname.

Just also want to point out that having Android connect directly the database is very bad practice, ideally you should be exposing the database using a REST webservice. Regarding doing operations on the main thread which as you have seen is not allowed. You need to learn about AsyncTask developer.android.com/reference/android/os/AsyncTask.html

So this...?

static final String DB_URL = "jdbc:mysql://137.58.72.178:3307/bars?autoReconnect=true";

Agree with point 2 - just want to see how the syntax of code works - will be doing it on a remote web server when app is put out - this is my first time to use a DB in it. It shows

EamonnDunne

veryangryman wrote: »

So this...?

static final String DB_URL = "jdbc:mysql://137.58.72.178:3307/bars?autoReconnect=true";

Agree with point 2 - just want to see how the syntax of code works - will be doing it on a remote web server when app is put out - this is my first time to use a DB in it. It shows

Its highly likely that IP address won't work as its your IP on the internet (I'm guessing). It will work if you open ports on your router and do port forwarding. However thats extremely bad security, you should be accessing it using your computers internal LAN IP address. These internal addresses typically start with 192. or 10.

h57xiucj2z946q

I recognise that IP address range, and that signum!, Someone doing side projects in work? :-p

If that IP don't allow incomming connections on port 3307 from whever your android connects from, you will still get conmection refused.

Are you using your phone or emulator?

EamonnDunne

Rebecca Careful Sequel wrote: »

I recognise that IP address range, and that signum!, Someone doing side projects in work? :-p

If that IP don't allow incomming connections on port 3307 from whever your android connects from, you will still get conmection refused.

Are you using your phone or emulator?

Yeah we all now know what company you both work for

h57xiucj2z946q

EamonnDunne wrote: »

Yeah we all now know what company you both work for

Haha as of lately, I don't work for them anymore!

veryangryman

Using the laptop for now.

h57xiucj2z946q

veryangryman wrote: »

Using the laptop for now.

So if you are using the Android SDK emulator to run your app, you can use 1.0.2.2 to collect to your dev machine.

Have a read here:
http://developer.android.com/tools/devices/emulator.html#networkaddresses