Question

我需要在我的JSF应用程序的会话范围中只保留一个对象。我在哪里定义会话变量，如何从视图文件或辅助bean中获取和设置它？

Answer 1

有几种方法：

使用ExternalContext#getSessionMap()

ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();
Map<String, Object> sessionMap = externalContext.getSessionMap();
sessionMap.put("somekey", yourVariable);

然后是：

SomeObject yourVariable = (SomeObject) sessionMap.get("somekey");

或者，将它作为会话范围bean的属性，将其注入请求范围的bean中。

sessionBean.setSomeVariable(yourVariable);

然后是：

SomeObject yourVariable = sessionBean.getSomeVariable();

如here所描述的faces-config.xml或者你已经使用JSF 2.0，@ManagedProperty

@ManagedBean
@RequestScoped
public class RequestBean {
    @ManagedProperty("#{sessionBean}")
    private SessionBean sessionBean;
    // ...
}

与

@ManagedBean
@SessionScoped
public class SessionBean {
    private SomeObject someVariable;
    // ...
}

Answer 2

Just moving along to JSF 2.2 and CDI 1.2 - Injection will at least be simpler. Keeping in line with the original answer of @BalusC:

import javax.enterprise.context.RequestScoped;
import javax.annotation.PostConstruct;
import javax.inject.Inject;
import javax.inject.Named;

@Named
@RequestScoped
public class RequestBean {
    @Inject
    private SessionBean sessionBean;
    // ...
    @PostConstruct
    void init() {
      // Interact with sessionBean during construction
      // but after Injection.
    }
}

with

import java.io.Serializable;
import javax.enterprise.context.RequestScoped;
import javax.inject.Inject;
import javax.inject.Named;

@Named
@SessionScoped
public class SessionBean implements Serializable {
    private SomeObject someVariable;
    // ...
}

There are several important notes to be made - particularly the switch to @Named, and the Fully Qualified Package Name for RequestScoped and SessionScoped. Also for making a Class SessionScoped it should also be made Serializable.

The addition of @Inject makes it really simple - but understand that the injected sessionBean object is only available after construction, not during. This means you do not have access to sessionBean within the constructor of RequestBean. This is solved by the use of @PostConstruct which gets triggered after injection is complete, and RequestBean is otherwise fully initialized.

Answer 3

当您调用方法FacesContext.getCurrentInstance()时，它将返回当前线程，但是在P.S.V.M的情况下，将不会在应用程序上下文中运行线程。所以你得到了NPE。

更好地使用这样的东西：

public String checker() {
    SessionFactory factory = HibernateUtil.getSessionFactory();
    Session session = factory.getCurrentSession();
    session.beginTransaction();
    Query q = session.createQuery("from UserLogin where UserId='"
            + uid.getUserId() + "'and Pswd='" + uid.getPswd()
            + "'and RoleId='" + uid.getRoleId() + "'");
    setUid((UserLogin) q.uniqueResult());

    System.out.println("upto here every thing is workind properly");

    if (uid != null) {
        FacesContext context = FacesContext.getCurrentInstance();

        HttpServletRequestrequest = (HttpServletRequest) context
                .getExternalContext().getRequest();
        HttpSession appsession = request.getSession(true);

        if (appsession.isNew() == false) {
            appsession.invalidate();
            appsession = request.getSession(true);
        }
        context.getExternalContext().getSessionMap().put("userbean", uid);
        session.close();
        return uid.getRoleId();
    } else
        return "invalid";
}

并将其放入会话bean中。您可以使用该代码验证用户。

如何在JSF中获取和设置会话范围中的对象？

3 个答案: