Java對象與記錄之間的綁定

我有一個嵌入式文檔的OrientDB數據庫與記錄，我不能回讀保存的實體。獲取正確數量的元素，但屬性未映射到我的pojo字段。我在做什麼錯？有小費嗎？Java對象與記錄之間的綁定

謝謝！

 OObjectDatabaseTx db = new OObjectDatabaseTx("local:db"); 
     if (db.exists()) { 
      db = new OObjectDatabaseTx("local:db").open("admin", "admin"); 
     } else { 
      db.create(); 
     } 

     db.getEntityManager().registerEntityClass(User.class); 

     long cnt = db.countClass(User.class); 
     System.out.println(cnt); // OK 

     User user = db.newInstance(User.class, "Firstname", "Lastname", "[email protected]"); 

     db.begin(); 
     db.save(user); // it's OK, the DB contains this document, I can select it with the servers console 
     db.commit(); 

     for (User usr : db.browseClass(User.class)) { 
      System.out.println(usr); // User object with null fields, why? 
     }

用戶等級：

public class User { 

private String firstname; 

private String lastname; 

private String email; 

public User() { 
} 

public User(String firstname, String lastname, String email) { 
    this.firstname = firstname; 
    this.lastname = lastname; 
    this.email = email; 
} 

public String getFirstname() { 
    return firstname; 
} 

public void setFirstname(String firstname) { 
    this.firstname = firstname; 
} 

public String getLastname() { 
    return lastname; 
} 

public void setLastname(String lastname) { 
    this.lastname = lastname; 
} 

public String getEmail() { 
    return email; 
} 

public void setEmail(String email) { 
    this.email = email; 
} 

@Override 
public String toString() { 
    return firstname + " " + lastname + " " + email; 
}

}

來源

2014-01-15 Rstrl