spring-mvc + jpa：数据绑定

我有简单的应用程序来管理橄榄球队和比赛。我正在使用JPA，格式为editMatch.jsp，我有属性team_1，team_2（班级团队的实例）从列表中选择团队。问题在于编辑匹配时，team_1和team_2不在列表中选择，并且在提交错误消息之后是：属性team_1抛出异常;嵌套异常是java.lang.NullPointerException。在控制器中，我绑定team_1，team_2，并且我认为错误在表单的绑定和初始化之间。spring-mvc + jpa：数据绑定

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(): ""); 
}

}

编辑：

errors.getFieldError（ “TEAM_1”）：在对象 '匹配' 现场 'TEAM_1'

字段错误：拒绝值[6];代码[methodInvocation.match.team_1，methodInvocation.team_1，methodInvocation.model.Team，methodInvocation];参数[org.springframework.context.support.DefaultMessageSourceResolvable：codes [match.team_1，team_1];参数[];预设讯息[team_1]];默认讯息[Property'team_1'引发异常;嵌套的例外是显示java.lang.NullPointerException]

来源

2010-10-23 mark

请显示完整的堆栈追踪。 – axtavt 2010-10-23 12:03:39

您实例TeamPropertyEditor但也不要称呼它setManager()，所以其manager场null，因此你想打电话manager.getTeamById(...)时获得NPE。

来源

2010-10-23 22:47:56 axtavt

spring-mvc + jpa：数据绑定

回答

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