121 lines
3.1 KiB
Markdown
121 lines
3.1 KiB
Markdown
# 显示登录信息
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---
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## 定义拦截器（实现 HandlerInterceptor）
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- 在请求开始时查询登录用户
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- **在本次请求中持有用户数据**
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通过 `ThreadLocal` 把用户数据存入当前线程对应的 map 里，只要本次请求未处理完，这个线程就一直还在，当请求处理完即服务器对本次请求做出响应后，这个线程被销毁
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- 在模板视图上显示用户数据
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- 在请求结束时清理用户数据
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```java
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@Component
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public class LoginTicketInterceptor implements HandlerInterceptor {
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@Autowired
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private UserService userService;
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@Autowired
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private HostHolder hostHolder;
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/**
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* 在 Controller 执行之前被调用
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* @param request
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* @param response
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* @param handler
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* @return
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* @throws Exception
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*/
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@Override
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public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
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// 从 cookie 中获取凭证
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String ticket = CookieUtil.getValue(request, "ticket");
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if (ticket != null) {
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// 查询凭证
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LoginTicket loginTicket = userService.findLoginTicket(ticket);
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// 检查凭证状态（是否有效）以及是否过期
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if (loginTicket != null && loginTicket.getStatus() == 0 && loginTicket.getExpired().after(new Date())) {
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// 根据凭证查询用户
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User user = userService.findUserById(loginTicket.getUserId());
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// 在本次请求中持有用户信息
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hostHolder.setUser(user);
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}
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}
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return true;
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}
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/**
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* 在模板引擎之前被调用
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* @param request
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* @param response
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* @param handler
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* @param modelAndView
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* @throws Exception
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*/
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@Override
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public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
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User user = hostHolder.getUser();
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if (user != null && modelAndView != null) {
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modelAndView.addObject("loginUser", user);
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}
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}
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/**
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* 在 Controller 执行之后（即服务端对本次请求做出响应后）被调用
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* @param request
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* @param response
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* @param handler
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* @param ex
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* @throws Exception
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*/
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@Override
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public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
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hostHolder.clear();
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}
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}
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```
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## 配置拦截器
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```java
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/**
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* 拦截器配置类
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*/
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@Configuration
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public class WebMvcConfig implements WebMvcConfigurer {
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@Autowired
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private LoginTicketInterceptor loginTicketInterceptor;
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@Override
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public void addInterceptors(InterceptorRegistry registry) {
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registry.addInterceptor(loginTicketInterceptor)
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.excludePathPatterns("/css/**", "/js/**", "/img/**");
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}
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}
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```
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## 前端
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```html
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<li th:if="${loginUser == null}">
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<a th:href="@{/register}">注册</a>
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</li>
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<img th:src="${loginUser.headerUrl}" />
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```
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