UserPropertyEditor中setAsText函数中的NullPointerException（Spring 3.2）

错误

java.lang.NullPointerException
    at com.javalabs.web.dao.UserPropertyEditor.setAsText(UserPropertyEditor.java:20)
...

我无法从表单属性userResponsible中绑定参数，在该属性中，我获取要绑定到对象任务的用户id。 但我得到的参数是userResponsible=1，它是来自数据库的用户。有什么想法吗

form.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>

<h1>Create task</h1>
<form:form method="GET" class="form-horizontal"
    action="${pageContext.request.contextPath}/docreatetask"
    commandName="task">
...
    <div class="form-group">
        <label for="userresponsible" class="col-sm-2 control-label">User
            responsible</label>
        <div class="col-sm-10">
            <form:select path="userResponsible"  name="userResponsible" class="form-control">
                <form:option value="0" label="Select" />
                <form:options items="${users}" itemValue="idUser"
                    itemLabel="username" />
            </form:select>
            <div id="state.error">
                <span class="text-danger"><form:errors path="userResponsible" /></span>
            </div>
        </div>
    </div>
...

userPropertyEdit.java

@Entity
@Table(name = "t_task")
public class Task {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "idTask")
    private long idTask;
    ...
    @ManyToOne
    @JoinColumn(name = "idUser_responsible", nullable = true)
    private User userResponsible;
    ...

public class UserPropertyEditor extends PropertyEditorSupport {

        private UserService userService;

        @Autowired
        public void setUserService(UserService userService) {
            this.userService = userService;
        }

        @Override
        public void setAsText(String text) throws IllegalArgumentException {
line 20:        super.setValue(userService.get(Long.parseLong(text)));
                //text variable is null when this function is called
            }
    }

...
@InitBinder
public void initBinder(WebDataBinder binder, HttpServletRequest req) {

    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-mm-dd");
    dateFormat.setLenient(false);
    binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
    binder.registerCustomEditor(State.class, new StatePropertyEditor());
    binder.registerCustomEditor(Category.class, new CategoryPropertyEditor());
    binder.registerCustomEditor(Priority.class, new PriorityPropertyEditor());
    binder.registerCustomEditor(User.class, "userResponsible", new UserPropertyEditor());
    //binder.registerCustomEditor(User.class, new UserPropertyEditor());
}
...

TaskController.java

@Entity
@Table(name = "t_task")
public class Task {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "idTask")
    private long idTask;
    ...
    @ManyToOne
    @JoinColumn(name = "idUser_responsible", nullable = true)
    private User userResponsible;
    ...

public class UserPropertyEditor extends PropertyEditorSupport {

        private UserService userService;

        @Autowired
        public void setUserService(UserService userService) {
            this.userService = userService;
        }

        @Override
        public void setAsText(String text) throws IllegalArgumentException {
line 20:        super.setValue(userService.get(Long.parseLong(text)));
                //text variable is null when this function is called
            }
    }

...
@InitBinder
public void initBinder(WebDataBinder binder, HttpServletRequest req) {

    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-mm-dd");
    dateFormat.setLenient(false);
    binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
    binder.registerCustomEditor(State.class, new StatePropertyEditor());
    binder.registerCustomEditor(Category.class, new CategoryPropertyEditor());
    binder.registerCustomEditor(Priority.class, new PriorityPropertyEditor());
    binder.registerCustomEditor(User.class, "userResponsible", new UserPropertyEditor());
    //binder.registerCustomEditor(User.class, new UserPropertyEditor());
}
...

---

我遗漏了什么？

在您的

initBinder

方法中，您正在自己构造

UserPropertyEditor

，因为这使它成为一个非spring管理的bean，

@Autowired

没有任何作用

您必须自己调用

setUserService

，或者要求应用程序上下文为您连接实例

@Controller
public class TaskController {
    @Autowired
    private UserService userService;

    @InitBinder
    public void initBinder(WebDataBinder binder, HttpServletRequest req) {
        UserPropertyEditor upe = new UserPropertyEditor();
        upe.setUserService(userService);
        binder.registerCustomEditor(User.class, "userResponsible", upe);
    }
}

当您自己调用setter时，您必须将

UserService

注入控制器，以便访问它。现在构造一个

UserPropertyEditor

并对其调用

setUserService

方法

@Controller
public class TaskController {
    @Autowired
    private ApplicationContext context;

    @InitBinder
    public void initBinder(WebDataBinder binder, HttpServletRequest req) {
        UserPropertyEditor upe = new UserPropertyEditor();
        context.getAutowireCapableBeanFactory().autowireBean(upe);
        binder.registerCustomEditor(User.class, "userResponsible", upe);
    }
}

---

使用

ApplicationContexct

时，必须将其注入控制器，获取

AutowireCapableBeanFactory

并对新构造的bean实例调用

autowireBean

方法。现在Spring将为您的对象执行任何注入和回调操作。

用户服务不会被注入，因为它不是Spring管理的，您应该自己设置。您说在哪里？在用户属性编辑器中？我将尝试您所说的，但现在我不明白为什么其他属性编辑器类的状态、类别和优先级似乎工作正常？问题是没有userService类，因此存在空指针。其他编辑器可能没有任何其他自动连接的依赖项或依赖项。关键是如果没有

UserService