ThreadLocal代码备忘-优快云博客

本文介绍了一种使用ThreadLocal来管理当前线程中用户登录状态的方法。通过SpringMVC拦截器，在请求处理前设置登录上下文，并在请求结束后清除，确保了线程安全性和资源的有效利用。

用ThreadLocal保存当前用户登录状态.在拦截器中获取登录用户的信息,并封装在ThreadLocal中,此后当前线程的调用过程中,都可以非常简单的获取登录用户的信息.

1. 拦截器(SpringMVC)

public class SecurityFilter implements HandlerInterceptor{


    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        //1) 从cookie中,或者请求的header中,获取有关认证信息
		//2) 或者从其他地方获取用户信息,比如DB,cache中等.
		LoginContext context = new LoginContext(user);
        LoginContextHolder.set(context);
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        //To change body of implemented methods use File | Settings | File Templates.
    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        LoginContextHolder.remove();//清理
    }
}

2. LoginContext.java

public class LoginContext {
    private User user;

    public LoginContext(User user){
        this.user = user;
    }
    public boolean isLogin(){
        return user == null ? false : true;
    }

    public User getLoginUser(){
        return user;
    }
}

3. LoginContextHolder.java

public class LoginContextHolder {

    private static final ThreadLocal<LoginContext> holder = new ThreadLocal<LoginContext>();

    public static void set(LoginContext context){
        if(context != null){
            holder.set(context);
        }
    }

    public static LoginContext getContext(){
        return holder.get();
    }

    public static void remove(){
        holder.remove();
    }

    public static boolean isLogin(){
        LoginContext context = getContext();
        if(context == null){
            return false;
        }
        return context.isLogin();
    }

    public static User getLoginUser(){
        LoginContext context = getContext();
        if(context == null || !context.isLogin()){
            return null;
        }
        return context.getLoginUser();
    }
}