spring-mvc + jpa：數據綁定

我有簡單的應用程序來管理橄欖球隊和比賽。我正在使用JPA，格式爲editMatch.jsp，我有屬性team_1，team_2（班級團隊的實例）從列表中選擇團隊。問題在於編輯匹配時，team_1和team_2不在列表中選擇，並且在提交錯誤消息之後是：屬性team_1拋出異常;嵌套異常是java.lang.NullPointerException。在控制器中，我綁定team_1，team_2，並且我認爲錯誤在表單的綁定和初始化之間。spring-mvc + jpa：數據綁定

editMatch.jsp

<form:select path="team_1"> 
     <form:options items="${teamList}" itemLabel="name" itemValue="id"/> 
    </form:select>

EditMatchController

public class EditMatchController extends SimpleFormController { 
private MatchManager manager; 
public EditMatchController() {} 

@Override 
protected void initBinder(HttpServletRequest request, ServletRequestDataBinder binder) throws Exception { 


    Match match = (Match)binder.getTarget(); 
    SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy"); 
    try{ 
     binder.registerCustomEditor(Date.class, "datum", new CustomDateEditor(sdf, false)); 
    } catch(Exception e){} 

    binder.registerCustomEditor(Team.class, new TeamPropertyEditor()); 
    binder.registerCustomEditor(Team.class, new TeamPropertyEditor()); 

} 

@Override 
protected Map referenceData(HttpServletRequest request) throws Exception { 
    Map<Object, Object> dataMap = new HashMap<Object, Object>(); 
    dataMap.put("teamList", manager.getTeams()); 
    return dataMap; 
} 

@Override 
protected Object formBackingObject(HttpServletRequest request) throws Exception { 
    int idMatch = Integer.parseInt(request.getParameter("id")); 
    Match match_d = manager.getMatchById(idMatch); 
    if (match_d == null) { 
     throw new GenericException("Neplatný záznam."); 
    } 
    return match_d; 
} 


@Override 
protected ModelAndView onSubmit(
     HttpServletRequest request, 
     HttpServletResponse response, 
     Object command, 
     BindException errors) throws Exception { 
    Match match = (Match)command; 
    manager.updateMatch(match); 
    RedirectView redirect = new RedirectView(getSuccessView()); 
    return new ModelAndView(redirect).addObject("message", match); 
} 

public void setManager(MatchManager manager) { 
    this.manager = manager; 
}

}

TeamPropertyEditor

public class TeamPropertyEditor extends PropertyEditorSupport { 

private MatchManager manager; 

public void setManager(MatchManager manager) { 
    this.manager = manager; 
} 


@Override 
public void setAsText(String text) throws IllegalArgumentException { 
    if (text != null && text.length() > 0) { 
      try { 
        Team team = this.manager.getTeamById(new Integer(text)); 
        super.setValue(team); 
      } catch (NumberFormatException ex) { 
        throw new IllegalArgumentException(); 
      } 
    } else { 
      super.setValue(null); 
    } 
} 

@Override 
public String getAsText() { 
    Team team = (Team) super.getValue(); 
    return (team != null ? (team.getId()+"").toString(): ""); 
}

}

編輯：

errors.getFieldError（「TEAM_1」）：在對象 '匹配' 現場 'TEAM_1'

字段錯誤：拒絕值[6];代碼[methodInvocation.match.team_1，methodInvocation.team_1，methodInvocation.model.Team，methodInvocation];參數[org.springframework.context.support.DefaultMessageSourceResolvable：codes [match.team_1，team_1];參數[];預設訊息[team_1]];默認訊息[Property'team_1'引發異常;嵌套的例外是顯示java.lang.NullPointerException]

來源

2010-10-23 mark

請顯示完整的堆棧追蹤。 – axtavt 2010-10-23 12:03:39

您實例TeamPropertyEditor但也不要稱呼它setManager()，所以其manager場null，因此你想打電話manager.getTeamById(...)時獲得NPE。

來源

2010-10-23 22:47:56 axtavt

spring-mvc + jpa：數據綁定

回答

相關問題