使用 <s：if> 标记检查用户是否在 Struts 2 中处于会话中

问：

我想知道是否可以检查 Struts 2 的标签是否用户在会话中。<s:if>

如果用户在会话中，我需要否则显示它。LogoutLogin

我使用登录操作的界面和这个类。SessionAwareUser

package it.pwm.wynd.pojo.user;


public class User implements java.io.Serializable {

    private static final long serialVersionUID = 1L;
    private Integer idUser;
    private String name;
    private String username;
    private String password;
    private String email;

    public User() {
    }

    public User(String name, String username, String password, String email) {
        this.name = name;
        this.username = username;
        this.password = password;
        this.email = email;
    }

    public Integer getIdUser() {
        return this.idUser;
    }

    public void setIdUser(Integer idUser) {
        this.idUser = idUser;
    }

    public String getName() {
        return this.name;
    }

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

    public String getUsername() {
        return this.username;
    }

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

    public String getPassword() {
        return this.password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return this.email;
    }

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


}