是EJB CMP實體bean的實際創建

Question

時，我有一個會話bean提供的商業方法，其中創建若干個CMP實體bean，像這樣

public void businessMethod(int number) { 
    try { 
     MyBeanHome home = lookupMyBean(); 
     DataSource dataSource = getMyDataSource(); 
     Statement statement = dataSource.getConnection().createStatement(); 
     ResultSet result; 
     String tableName = "MYBEAN"; 
     for (int i = 0; i < number; i++) { 
      result = statement.executeQuery("select max(ID) + 1 from " + tableName); 
      result.next(); 
      int newID = result.getInt(1); 
      System.out.println(newID); 
      MyBeanLocal lineLocal = home.create(newID); 
     } 
    } catch (Exception ex) { 
     ex.printStackTrace(); 
    } 
} 

的MyBean的製作方法簡單地創建一個新豆與newID。但是，上述代碼僅適用於number = 1。如果number > 1，它嘗試創建具有相同ID的第二個bean（System.out.println(newID);打印相同的值）。我猜新bean尚未存儲在數據庫中，因此查詢返回相同的值。對此可以做些什麼？

非常感謝！

Answer 1

我發現只有在業務方法完成時才執行事務，所以第一個實體bean不會被存儲在數據庫中以供檢索。一個簡單的解決方案如下

public void businessMethod(int number) { 
    try { 
     MyBeanHome home = lookupMyBean(); 
     DataSource dataSource = getMyDataSource(); 
     Statement statement = dataSource.getConnection().createStatement(); 
     ResultSet result; 
     String tableName = "MYBEAN"; 
     result = statement.executeQuery("select max(ID) + 1 from " + tableName); 
     result.next(); 
     int newID = result.getInt(1); 
     for (int i = 0; i < number; i++) { 
      System.out.println(newID); 
      MyBeanLocal lineLocal = home.create(newID++); 
     } 
    } catch (Exception ex) { 
     ex.printStackTrace(); 
    } 
}