将对象的现有关系标记为

Question

我的Spring MVC应用程序具有一个具有USER_ROLES n的域USER

public class User {
...
    @ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.DETACH})
    @JoinTable(name = "L_USER_ROLE", catalog = "PUBLIC", joinColumns = { 
            @JoinColumn(name = "fk_user", nullable = false, updatable = false) }, 
            inverseJoinColumns = { @JoinColumn(name = "fk_role", 
                    nullable = false, updatable = false) })
    private List<UserRole> hasRoles;
...
}

在JSP页面中，可以编辑用户，也可以将User_Roles分配给用户。

user.jsp

    <div class="form-group">
        <label class="col-sm-2 control-label" for="hasRoles">Roles</label>

        <!--  Test to see, if the user has roles (this part displays the correct Roles -->          
        <c:forEach items="${userObj.hasRoles}" var="role">
            ${role.role}<br>
        </c:forEach>

        <!--  here the existing roles should be highlighted, but this does not work -->
        <div class="col-sm-7">
                <form:select path="hasRoles" items="${userRoles}" multiple="true" itemValue="id" itemLabel="role" class="form-control input-sm" />
                <div class="has-error">
                    <form:errors path="hasRoles" class="help-inline"/>
                </div>
            </div>
    </div>

我没有显示控制器，因为实际上编辑角色分配可以正常工作。我还可以看到，jsp中提供了hasRoles集合。 唯一的问题是，在我的可用角色列表中，当前分配的角色未突出显示。

@Entity
@Table(name = "USER_ROLES", catalog = "PUBLIC", uniqueConstraints = {
        @UniqueConstraint(columnNames = "ROLE"),
         })
public class UserRole {

    @Id
    @GeneratedValue
    private int id;

    private String role;


    @Override
    public boolean equals(Object that) {
        UserRole thatRole = (UserRole)that;
        if (thatRole.role == null || this.role == null)
            return false;
        return this.role.equals(thatRole);
    }

    @Override
    public int hashCode() { 
        return this.role.hashCode();
    }

    public int getId() {
        return id;
    }

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

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }   


}