版权声明: https://blog.csdn.net/qq_21852449/article/details/84331917
ThreadLocal用于保存某个线程共享变量:对于同一个static ThreadLocal,不同线程只能从中get,set,remove自己的变量,而不会影响其他线程的变量。
1、ThreadLocal.get: 获取ThreadLocal中当前线程共享变量的值。
2、ThreadLocal.set: 设置ThreadLocal中当前线程共享变量的值。
3、ThreadLocal.remove: 移除ThreadLocal中当前线程共享变量的值。
4、ThreadLocal.initialValue: ThreadLocal没有被当前线程赋值时或当前线程刚调用remove方法后调用get方法,返回此方法值。
/**
* 在Javaweb中通过ThreadLocal处理高并发 ,可以理解为ThreadLocal相当于一个map ,其中key是我们当前的进程,这样不同进程之间的数据就进行了分离。
*/
public class RequestHolder {
private static final ThreadLocal<SysUser> userHolder = new ThreadLocal<SysUser>();
private static final ThreadLocal<HttpServletRequest> requestHolder = new ThreadLocal<HttpServletRequest>();
public static void add(SysUser sysUser) {
userHolder.set(sysUser);
}
public static void add(HttpServletRequest request) {
requestHolder.set(request);
}
public static SysUser getCurrentUser() {
return userHolder.get();
}
public static HttpServletRequest getCurrentRequest() {
return requestHolder.get();
}
public static void remove() {
userHolder.remove();
requestHolder.remove();
}
}
/**
* 校验用户是否登录
*/
@Slf4j
public class LoginFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) servletRequest;
HttpServletResponse res = (HttpServletResponse) servletResponse;
String servletPath = req.getServletPath();
SysUser sysUser = (SysUser) req.getSession().getAttribute("user");
if (sysUser == null) {
String path = "/signin.jsp";
res.sendRedirect(path);
return;
}
RequestHolder.add(sysUser);
RequestHolder.add(req);
filterChain.doFilter(servletRequest, servletResponse);
return;
}
@Override
public void destroy() {
}
}
代码可以实现从项目的任何位置获取当前登录的用户和当前的Request。