带有Java Rest Web服务的手动DbConnection（球衣）

Question

I was wondering if anyone could help me with a small problem. I'm trying to create a restfull service in Java using Jersey.

But I cannot find any examples on how to make a manual db connections. And If I do, the connection returns a nullpointer when querying the database.

public DbConnection()
{
    try 
    {
        // This will load the MySQL driver, each DB has its own driver
        Class.forName("com.mysql.jdbc.Driver");
        // Setup the connection with the DB
        connection =     DriverManager.getConnection("jdbc:mysql://url/team_staging?"
                        + "user=X&password=X");
    }
    catch (ClassNotFoundException ex) 
    {
        Logger.getLogger(DbConnection.class.getName()).log(Level.SEVERE, null, ex);
    } 
    catch (SQLException ex) 
    {
        Logger.getLogger(DbConnection.class.getName()).log(Level.SEVERE, null, ex);
    }
}

Could someone point my in the right direction here? I don't want to use any ORM.

I find it hard to find good examples without hibernate or auto-generated rest service in netbeans...

My regards, Axl

Answer 1

I think your instinct to steer clear of an ORM solution is a good one.

You're writing a web service, which means it's deployed on a servlet/JSP engine at a minimum (eg Tomcat) or a full Java EE app server. I'd learn how to create a JNDI connection pool for your app server.

You want to externalize your connection parameters (eg driver, URL, etc.)

I don't see a class member for that connection. What happens when you exit the ctor? Is it out of scope? That would explain the NPE.

I'd write it this way:

package persistence;

public class DatabaseUtils {
    private DatabaseUtils() {}

    public static Connection getConnection(String driver, String url, String username, String password) throws Exception {
        Class.forName(driver);
        return DriverManager.getConnection(url, username, password);
    }
}