MySql在已部署的Java Web应用程序中不起作用

Question

I made a page using struts. When running on localhost (glassfish) it is working fine. However, when I copy WAR file to a remote server and run the application from there login form does not work. That means something is wrong when connecting on mysql database.

How could I solve this?

Code snippet:

Connection conn = null;
    Statement stmt = null;
    try{
        InitialContext ctx = new InitialContext();
        DataSource ds = (DataSource)ctx.lookup("jdbc/SB");


        conn = ds.getConnection();
        stmt = conn.createStatement();
        ResultSet rs = null;
        if(stmt.execute("SELECT * FROM users WHERE username='"+loginform.getUsername()+"' AND geslo=MD5('"+loginform.getPassword()+"') LIMIT 1;"))
        {
    rs = stmt.getResultSet();
        }

        rs.next();

Unfortunately I cannot read from the server console. What else should I do to see the exception (remote logging?)?

Thanks on replies.

UPDATE: - Both locally and remotely GlassFish 3.0.1 is running. - My working environment is NetBeans 6.9.1. - Deploying locally is done simply in NetBeans. I just click on the project name and click publish. For remote deployment, admin gave me access to the FTP server where I just copy the WAR file. - MySQL server is located somewhere else. The point is, it is accessible from the localhost web application but not from the same remote web application.

Answer 1

Assuming you have admin rights on the remote server, you need to

1. Verify that the datasource "jdbc/SB" exists. (Resources / JDBC / JDBC Resources)
2. Verify that the "poolname" in the datasoucre exists (Resources / JDBC/ Connection Pools)
3. Open the appropriate connection pool and click on the "ping" button.
4. If ping fails verify the connection params under the Additional Properties tab.

There could be a dozen other issues as well. You really need to get access to the server log so you see what the specific exception is. It's unlikely it's your code and more likely that the remote server is missing the driver dependency or isn't properly configured (the connection pool an datasource)

Answer 2

Some ideas are
- log to file instead of console
- Print log on your struts page
- maybe you don't have grants or firewall problem to access DB

Answer 3

I'd bet that you don't have authority to access the DB...

Try this as a test... install the MySQL client on another machine and then connect to the MySQL server from there.

If that fails then:

Say you log in with: User: test Password: password

Then open the Mysql client and enter:

use nameOfDatabase;
GRANT ALL ON nameofDatabase.* TO 'userName'@'ipaddressOfServerOrDNSName';

That should do it.

There are other ways to give access see http://dev.mysql.com/doc/refman/5.1/en/grant.html

Answer 4

Are you sure your database is setup correctly on your remote server? It sounds like maybe a firewall issue.

Answer 5

Unfortunately I cannot read from the server console.

If you have shell access to the remote server, the solution is simple:

• Change the logging configs so that your webapp logs to a file instead of / as well as the console.
• Login and read the file.

(Indeed, if you were using Tomcat, stuff written to System.out / System.err is written to a file anyway. Maybe this is true for Glassfish also.)

If you don't have shell access, you may have to modify your webapp to provide an extra page that can be used to download or view the log file from your web browser. If you have to resort to this, pay attention to the obvious security concerns.

Answer 6

This is my weg (wild eyed guess)....

Your local app server has the MySql driver installed. The JDBC resource is also defined correctly. The MySql server is probably running on your localhost. You have developed your app locally in NetBeans.

When you deploy an app from NetBeans onto a local server, the IDE makes sure that server has the DB driver installed. NetBeans cannot do that when you deploy to a remote host. If you use some other deployment method, driver installation is not automagic. It is an easy step to forget.

You can find out if the MySql drive is installed on your server by writing a web app that attempts to load or use one of the classes from the driver jar file. If the access generates an exception, you can probably get something that works by including the MySql drive in your webapp's WEB-INF/lib.

NetBeans also helps folks create and manage their JDBC resource definitions. If you create an app that targets a database on your localhost, the JDBC resource will have localhost as part of the URL. This will work great when the app is deployed onto the same server as the DB server. If the app is moved to another server, the JDBC resource needs to be changed to account for the possibility that the DB server is NOT on the localhost.

If you do not have admin access to the remote server, you will have trouble getting the resources defined. If your remote server was a GlassFish 3.1 domain/instance, you could leverage application scoped resources to get the resources defined for your app.

Regarding access to the log file.

If you are using asadmin to deploy onto the remote server, this command will help you access the server log if you are working with GlassFish v2.x: http://docs.sun.com/app/docs/doc/821-0179/display-log-records-1?l=en&a=view . You can also access the log via the admin console.

If you are using rcp to deploy your app, by copying it into the autodeploy directory of the remote server, you may want to see if you can copy the log onto your local machine.

For example... if your admin told you to deploy using an ftp command like this:

ftp> cd /a/b/glassfish/domains/domain1/autodeploy
ftp> put MyGreatWebapp.war

you may be able to get the log by doing something like this:

ftp> cd /a/b/glassfish/domains/domain1/logs
ftp> get server.log

Experiment....