课次29：拦截器实现Token校验 + ThreadLocal
一、教学目标
创建拦截器，对除登录注册外的接口进行token校验。
使用ThreadLocal存储当前用户ID。
二、核心知识点（简要）
HandlerInterceptor：Spring MVC拦截器接口。
ThreadLocal：线程局部变量，每个线程独立存储。
token校验：从请求头获取token，解析验证，若无效返回401。
三、操作步骤

  1. 创建UserContext
    右键util文件夹，新建java类：UserContext

UserContext中的代码如下：

package com.weitoutiao.util;

public class UserContext {
private static final ThreadLocal currentUserId = new ThreadLocal<>();

public static void setCurrentUserId(Integer userId) {
currentUserId.set(userId);
}
public static Integer getCurrentUserId() {
return currentUserId.get();
}
public static void clear() {
currentUserId.remove();
}
}
2. 创建JwtInterceptor
右键com.weitoutiao,新建java类：interceptor.JwtInterceptor

interceptor.JwtInterceptor中的代码如下：

package com.weitoutiao.interceptor;

import com.weitoutiao.util.JwtUtil;
import com.weitoutiao.util.UserContext;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

@Component
public class JwtInterceptor implements HandlerInterceptor {
@Autowired
private JwtUtil jwtUtil;

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
String token = request.getHeader("Authorization");
if (token != null && token.startsWith("Bearer ")) {
token = token.substring(7);
if (jwtUtil.validateToken(token)) {
Integer userId = jwtUtil.getUserIdFromToken(token);
UserContext.setCurrentUserId(userId);
return true;
}
}
response.setStatus(401);
response.setContentType("application/json;charset=utf-8");
response.getWriter().write("{"code":401,"message":"未登录或token失效"}");
return false;
}

@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
UserContext.clear();
}
}
3. 配置拦截器
右键config文件夹，新建java类：InterceptorConfig

InterceptorConfig中的代码如下：

package com.weitoutiao.config;

import com.weitoutiao.interceptor.JwtInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
@Autowired
private JwtInterceptor jwtInterceptor;

@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(jwtInterceptor)
.addPathPatterns("/**")
.excludePathPatterns("/user/login", "/user/register");
}
}
4.工程目录结构

课次29：拦截器实现Token校验 + ThreadLocal
一、教学目标
二、核心知识点（简要）
三、操作步骤
1. 创建UserContext
2. 创建JwtInterceptor
3. 配置拦截器
4.工程目录结构

EOF