JDBC连接池(Glassfish)的正确使用 [英] Proper usage of JDBC Connection Pool (Glassfish)

问题描述

我需要一个作为会话 bean 实现的 Java Web 服务中的数据库连接，但我不确定我是否做得对.

I need a database connection in Java Web service implemented as a session bean, and I'm not sure if I do it right.

我创建了一个类

public final class SQLUtils   {  
    //.....  
    private static DataSource  m_ds=null;    

    static  
    {  
        try
        {
            InitialContext ic = new InitialContext();
            m_ds = (DataSource) ic.lookup(dbName); //Connection pool and jdbc resource previously created in Glassfish  , dbName contains the proper JNDI resource name 

        }
        catch (Exception e)
        {
            e.printStackTrace();
            m_ds = null;
        }

    }

    public static Connection getSQLConnection() throws SQLException  
    {  
        return m_ds.getConnection();             
    }
}

每当我需要连接时我都会

Whenever I need a connection I do

 Connection cn = null;  
 try  
 {
     cn = SQLUtils.getSQLConnection();
     // use connection
 }
 finally 
 {
     if (null != cn)
     {
         try
         {
             cn.close();
         }
         catch (SQLException e)
         {

         }
     }
 }

这样使用可以吗，还是我DataSource必须是bean的成员?

Is it ok to use it this way, or I DataSource must be a member of the bean ?

  @Stateless  
  @WebService  
  public class TestBean  {  
   private @Resource(name=dbName) DataSource m_ds;   
  }  

很抱歉，如果这是一个麻烦的问题，但我对 Java 还很陌生.提前致谢.

I'm sorry if it is a nube question, but I'm pretty new to Java. Thanks in advance.

推荐答案

除了 C 风格的格式、一些不必要的行和有点糟糕的异常处理之外，你可以这样做.

Apart from the C-style formatting, a few unnecessary lines and a bit poor exception handling, you can just do so.

这是我的做法:

public final class SQLUtil {
    private static DataSource dataSource;
    // ..

    static {
        try {
            dataSource = (DataSource) new InitialContext().lookup(name);
        } catch (NamingException e) {
            throw new ExceptionInInitializerError(e);
        }
    }

    public static Connection getConnection() throws SQLException {  
        return dataSource.getConnection();             
    }
}

我在这里抛出 ExceptionInInitializerError 这样应用程序就会立即停止，这样您在尝试获取连接时就不需要面对无法解释的"NullPointerException.

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