java - Spring - 如何获取列表框jsp中的对象列表

Question

我不明白为什么，当我在 jsp 文件中提交 spring 表单时，我可以获得对象角色列表，但没有填充(id，roleName)。我的表单允许创建新用户，并且一个用户可以拥有多个角色。

这是我的模型用户

@Entity
public class User implements Serializable{
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private int id;
private String username;
private String password;
@ManyToMany(fetch = FetchType.EAGER,cascade = CascadeType.ALL)
@JoinTable(name="userandrole",
        joinColumns=@JoinColumn(name="user_id"),
        inverseJoinColumns=@JoinColumn(name="role_id"))
private List<Role> roles;
@Enumerated(EnumType.STRING)
private UserStatus status;
@ManyToOne
@JoinTable(name="userandpartenaire",
joinColumns=@JoinColumn(name="user_id"),
inverseJoinColumns=@JoinColumn(name="partenaire_id"))
private Partenaire partenaires;
//......}

这是我的模型角色

@Entity
public class Role {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private int id;
private String roleName;
@ManyToMany(mappedBy = "roles",fetch = FetchType.EAGER)
private List<User> users;
//..... }

这是我的 Controller 。首先将用户和角色列表发送到jsp

@RequestMapping("/gestionAdmin")
public String setupForm(Map<String, Object> map){
    //System.out.println(fonction.hasRole("Partenaire"));
    User user = new  User();
    user.setRoles(new AutoPopulatingList<Role>(Role.class));
    List<User> usersList = userService.getAllUsers();
    Hibernate.initialize(usersList);
    map.put("user", user);
    map.put("usersList",usersList );
    map.put("rolesList", roleService.getAlltRoles());
    return "gestionAdmin";

}

JSP文件

<form:form action="gestionAdmin.do" method="POST" commandName="user">
    <table>
        <tr>
            <td>username</td>
            <td><form:input path="username" /></td>
        </tr>
        <tr>
            <td>password</td>
            <td><form:input path="password" /></td>
        </tr>
        <tr>
            <td>Roles</td>
            <td><form:select path="roles" multiple="true" items="${rolesList}" itemLabel="roleName">
                </form:select>
            </td>
        </tr>
        <tr>
            <td>Status</td>
            <td><form:select path="status">  
             <form:option value="ACTIVE" label="Active"/>  
             <form:option value="INACTIVE" label="Inactive"/>  
         </form:select> </td>
        </tr>
        <tr>
            <td>
                <input type="submit" name="action" value="Search" />
                <input type="submit" name="action" value="Add" />
                <input type="submit" name="action" value="Update" />
            </td>
        </tr>
    </table>
</form:form>

最后是我可以获取表单信息的函数。在这里我遇到了错误 NullPointerException 因为我尝试在对象 User 中获取角色的 id 角色名称(在 for 循环中查找 syso)

@RequestMapping(value="/gestionAdmin.do",  method=RequestMethod.POST)
public String setupFormAdmin(@ModelAttribute("user") @Valid User user,BindingResult result,Map<String, Object> map,@RequestParam String action){
    System.out.println(fonction.hasRole("Partenaire"));
    User users = new  User();
    User usersTest = userService.findUserByName(user.getUsername());
    User usersTestId = userService.findUser(user.getId());
    List<Role> roleList = new ArrayList<Role>();
    String messages="";
    //System.out.println("ooooo" + user.getPassword());
    if( fonction.hasRole("Admin")){
        switch (action.toLowerCase()) {
        case "add":             
            String mdp = user.getPassword();
            user.setPassword(fonction.encode(mdp));
            System.out.println(user.getRoles().size()); // Here my size of getRole is > 0 
            for (Role role : user.getRoles()) {
                //roleList.add(roleService.findRole(1));
                System.out.println(role.getRoleName() + " "+ role.getId()+"); // error NullPointerExcepction
            }
            user.setRoles(roleList);
            if(usersTest==null){
                userService.addUser(user);
            }else{
                messages="Utilisateur déja présent dans la base de donné";
            }
            break;

谢谢(对不起我的英语)

Answer 1

我找到了解决办法

在 Controller 中我添加了角色的@InitBinder

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

   // super.initBinder(request, binder);

    binder.registerCustomEditor(List.class, "roles",new CustomCollectionEditor(List.class){

        @Override
        protected Object convertElement(Object element) {
            Role role = new Role();
            if (element != null && (element.toString().equals("1") || element.toString().equals("2") || element.toString().equals("3") || element.toString().equals("4"))) {

                role.setId(Integer.parseInt(element.toString()));
            }
            return role;
        }
    });
}

并在表单中添加 itemsValue

<form:select path="roles" multiple="true" items="${rolesList}" itemLabel="roleName" itemValue="id">