Question

是否可以在Validator中@Autowired DAO？我使用它时得到一个nullpointer。当在验证器中调用userDAO时，运行this会给我一个NullPointerException。我包含了所有代码和应用程序上下文

public class UserFormValidator implements Validator {

@Autowired
private UserDAO userDAO;  

@Override
public boolean supports(Class<?> clazz) {
    return UserForm.class.equals(clazz);
}

@Override
public void validate(Object target, Errors errors) {
    System.out.println ("User -> " + userDAO.findById(new Integer(1)));
}
}

@Repository("userDAO")
public class UserDAOImpl extends GenericDAOImpl implements UserDAO {

public UserDAOImpl() {
    super();
}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:sws="http://www.springframework.org/schema/web-services"
xsi:schemaLocation="http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc 
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/web-services 
        http://www.springframework.org/schema/web-services/web-services-2.0.xsd">

<!-- Activates various annotations to be detected in bean classes -->
<context:annotation-config />

<!-- Scans the classpath for annotated components that will be auto-registered 
    as Spring beans. For example @Controller and @Service. Make sure to set the 
    correct base-package -->
<context:component-scan base-package="com.myapp" />
<context:annotation-config/>



<!-- Configures the annotation-driven Spring MVC Controller programming 
    model. Note that, with Spring 3.0, this tag works in Servlet MVC only! -->
<mvc:annotation-driven />

<!-- Load Hibernate related configuration -->
<!-- Here you can also add spring security context, if exist -->
<import resource="hibernate-context.xml" />


</beans>

谢谢！

Answer 1

尝试将@Component注释添加到UserFormValidator

Answer 2

改变

binder.setValidator（new UserFormValidator（））;

代表

binder.setValidator（userFormValidator）;

解决了问题

Answer 3

验证程序包名称：com.myapp。

添加@Component注释：

这里有控制器，我实例化Validator

@Controller
public class HomeController {

private static final Logger logger = LoggerFactory.getLogger(HomeController.class);


@InitBinder
protected void initBinder(WebDataBinder binder) {
    binder.setValidator(new UserFormValidator());
}

/**
 * Simply selects the home view to render by returning its name.
 */
@RequestMapping(value = "/home", method = RequestMethod.GET)
public String home(Locale locale, Model model) {

    model.addAttribute("userForm", new UserForm());
    return "home";
}

@RequestMapping(value = "/login",method = RequestMethod.POST)
 public String submitForm(@Valid UserForm  userForm, BindingResult result,ModelMap model) {

  if (result.hasErrors()) {
         return "home";
     }

  model.addAttribute("userForm",userForm);
  return "doors";

 }

@ModelAttribute("userForm")
public UserForm createModel() {
    return new UserForm();
}

}

@Autowired一个验证器内的DAO

3 个答案: