Spring 绑定 List<Object> 到 Form:checkboxes

Question

我似乎无法让我的表单绑定到复选框控件。我在这里阅读了很多帖子并尝试了一些技术，但没有运气。也许换一双眼睛会有所帮助。

我的控制器：

public String editAccount(@RequestParam("id") String id, Model model) {
    model.addAttribute("account", accountService.getAccount(id));
    model.addAttribute("allRoles", roleService.getRoles());
    return EDIT_ACCOUNT;
}

我的jsp：

<form:form action="" modelAttribute="account">
<form:checkboxes items="${allRoles}" path="roles" itemLabel="name" itemValue="id" delimiter="<br/>"/>
</form>

生成的html：

<span><input id="roles1" name="roles" type="checkbox" value="1"/><label for="roles1">User</label></span><span><br/><input id="roles2" name="roles" type="checkbox" value="2"/><label for="roles2">Admin</label></span><span><br/><input id="roles3" name="roles" type="checkbox" value="3"/><label for="roles3">SuperAdmin</label></span<input type="hidden" name="_roles" value="on"/>

我为每个循环（未显示）使用了第二个，以确保模型对象包含角色。确实如此，但是没有选中任何复选框，并且当我提交角色对象时，它始终为空。有人可以告诉我我缺少什么吗？

谢谢

编辑

抱歉，刚刚意识到查看帐户和角色对象可能会有所帮助：

public class Account {

    private String username, firstName, lastName, email;
    private List<Role> roles;

    @NotNull
    @Size(min = 1, max = 50)
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @NotNull
    @Size(min = 1, max = 50)
    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    @NotNull
    @Size(min = 1, max = 50)
    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @NotNull
    @Size(min = 6, max = 50)
    public String getEmail() {
        return email;
    }

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

    public List<Role> getRoles() {
        return roles;
    }

    public void setRoles(List<Role> roles) {
        this.roles = roles;
    }

    public String toString() {
        return ReflectionToStringBuilder.toString(this);
    }

}

public class Role {

private int id;
private String name;

public Role() {}

public Role(int id, String name) {
    this.id = id;
    this.name = name;
}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

@NotNull
@Size(min = 1, max = 50)
public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

}

编辑#2

控制器发布方法

@RequestMapping(value = "edit", method = RequestMethod.POST)
public String updateAccount(@RequestParam("id") String id, @ModelAttribute("account") @Valid AccountEditForm form, BindingResult result) {
    System.out.println("FORM VALUES AFTER: " + form);
    return (result.hasErrors() ? EDIT_ACCOUNT : ACCOUNT_REDIRECT);
}

AccountEditForm 是表单支持对象。当我执行 GET 时，我会抓取一个 Account 对象并将值传递给 AccountEditForm，然后再显示屏幕。为了清楚起见，我将附上 AccountEditForm。它与帐户对象非常相似。我只是碰巧将我的表单对象与我的模型对象分开。

public class AccountEditForm {

    private String username, firstName, lastName, email;
    private List<Role> roles = new ArrayList<Role>();

    @NotNull
    @Size(min = 1, max = 50)
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @NotNull
    @Size(min = 1, max = 50)
    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    @NotNull
    @Size(min = 1, max = 50)
    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @NotNull
    @Size(min = 6, max = 50)
    public String getEmail() {
        return email;
    }

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

    public List<Role> getRoles() {
        return roles;
    }

    public void setRoles(List<Role> roles) {
        this.roles = roles;
    }

    public String toString() {
        return ReflectionToStringBuilder.toString(this);
    }

}

EDIT #3 角色属性编辑器

public class RolePropertyEditor extends PropertyEditorSupport {

    private Map<Integer, Role> roleMap = new HashMap<Integer, Role>();

    public RolePropertyEditor(List<Role> roleList) {
        for (Role r : roleList) roleMap.put(r.getId(), r);
    }

    public void setAsText(String incomingId) {
        Role role = roleMap.get(incomingId);
        System.out.println("PROPERTY EDITOR ROLE " + role);
        setValue(role);
    }

    public String getAsText() {
        System.out.println("PROPERTY EDITOR ID " + ((Role)getValue()).getId());
        return String.valueOf(((Role)getValue()).getId());
    }
}

在我的控制器中定义如下：

@InitBinder
public void initBinder(WebDataBinder binder) {
    binder.setAllowedFields(new String[] {
            "username", "password", "confirmPassword", "firstName", "lastName", "email", "acceptTerms", "currentPassword"
    });
    binder.registerCustomEditor(Role.class, new RolePropertyEditor(roleService.getRoles()));
}

编辑 #4 新的 ProeprtyEditor

public class SecurityRolePropertyEditor extends PropertyEditorSupport {

    private RoleService roleService;

    public SecurityRolePropertyEditor(RoleService roleService) {
        this.roleService = roleService;
    }

    public void setAsText(final String name) {
        Role role = roleService.getRoleByName(name);
        setValue(role);
    }
}

Answer 1

为你的 Roles 实体添加一个 equals 方法。

有关更多详细信息，请参阅此answer (Spring MVC Pre Populate Checkboxes): of a similar question。

Answer 2

您的实体上似乎缺少实现 equals 和 hashCode 方法。