介绍：
ThreadLocal 并不是一个Thread，而是Thread的局部变量。
ThreadLocal为每个线程提供单独一份存储空间，具有线程隔离的效果，只有在线程内才能获取到对应的值，线程外则不能访问。常用方法：
- public void set(T value) 设置当前线程的线程局部变量的值
- public T get() 返回当前线程所对应的线程局部变量的值
- public void remove() 移除当前线程的线程局部变量
public class BaseContext {
public static ThreadLocal<Long> threadLocal = new ThreadLocal<>();
public static void setCurrentId(Long id) {
threadLocal.set(id);
}
public static Long getCurrentId() {
return threadLocal.get();
}
public static void removeCurrentId() {
threadLocal.remove();
}
}
在拦截器中解析出当前登录员工id，并放入线程局部变量中：
/**
* jwt令牌校验的拦截器
*/
@Component
@Slf4j
public class JwtTokenAdminInterceptor implements HandlerInterceptor {
@Autowired
private JwtProperties jwtProperties;
/**
* 校验jwt
*
* @param request
* @param response
* @param handler
* @return
* @throws Exception
*/
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//判断当前拦截到的是Controller的方法还是其他资源
if (!(handler instanceof HandlerMethod)) {
//当前拦截到的不是动态方法，直接放行
return true;
}
//1、从请求头中获取令牌
String token = request.getHeader(jwtProperties.getAdminTokenName());
//2、校验令牌
try {
log.info("jwt校验:{}", token);
Claims claims = JwtUtil.parseJWT(jwtProperties.getAdminSecretKey(), token);
Long empId = Long.valueOf(claims.get(JwtClaimsConstant.EMP_ID).toString());
log.info("当前员工id:{}", empId);
/////将用户id存储到ThreadLocal////////
BaseContext.setCurrentId(empId);
////////////////////////////////////
//3、通过，放行
return true;
} catch (Exception ex) {
//4、不通过，响应401状态码
response.setStatus(401);
return false;
}
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
//清空ThreadLocal中的数据
BaseContext.removeCurrentId();
}
}
@Configuration
@Slf4j
public class WebMvcConfiguration extends WebMvcConfigurationSupport {
@Autowired
private JwtTokenAdminInterceptor jwtTokenAdminInterceptor;
@Autowired
private JwtTokenUserInterceptor jwtTokenUserInterceptor;
/**
* 注册自定义拦截器
*
* @param registry
*/
protected void addInterceptors(InterceptorRegistry registry) {
log.info("开始注册自定义拦截器...");
registry.addInterceptor(jwtTokenAdminInterceptor)
.addPathPatterns("/admin/**")
.excludePathPatterns("/admin/employee/login");
registry.addInterceptor(jwtTokenUserInterceptor)
.addPathPatterns("/user/**")
.excludePathPatterns("/user/user/login")
.excludePathPatterns("/user/shop/status");
}
}
在Service中获取线程局部变量中的值：
/**
* 新增员工
*
* @param employeeDTO
*/
public void save(EmployeeDTO employeeDTO) {
//.............................
//设置当前记录创建人id和修改人id
employee.setCreateUser(BaseContext.getCurrentId());
employee.setUpdateUser(BaseContext.getCurrentId());
employeeMapper.insert(employee);
}
使用map
/**
* ThreadLocal 工具类
*/
@SuppressWarnings("all")
public class ThreadLocalUtil {
//提供ThreadLocal对象,
private static final ThreadLocal THREAD_LOCAL = new ThreadLocal();
//根据键获取值
public static <T> T get(){
return (T) THREAD_LOCAL.get();
}
//存储键值对
public static void set(Object value){
THREAD_LOCAL.set(value);
}
//清除ThreadLocal 防止内存泄漏
public static void remove(){
THREAD_LOCAL.remove();
}
}
@Component
public class LoginInterceptor implements HandlerInterceptor {
@Autowired
private StringRedisTemplate stringRedisTemplate;
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//令牌验证
String token = request.getHeader("Authorization");
//验证token
try {
Map<String, Object> claims = JwtUtil.parseToken(token);
//把业务数据存储到ThreadLocal中
ThreadLocalUtil.set(claims);
//放行
return true;
} catch (Exception e) {
//http响应状态码为401
response.setStatus(401);
//不放行
return false;
}
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
//清空ThreadLocal中的数据
ThreadLocalUtil.remove();
}
}
@GetMapping("/userInfo")
public Result<User> userInfo(/*@RequestHeader(name = "Authorization") String token*/) {
//根据用户名查询用户
/* Map<String, Object> map = JwtUtil.parseToken(token);
String username = (String) map.get("username");*/
Map<String, Object> map = ThreadLocalUtil.get();
String username = (String) map.get("username");
User user = userService.findByUserName(username);
return Result.success(user);
}
ThreadLocal:
- 用来存取数据: set()/get()
- 使用ThreadLocal存储的数据, 线程安全
- 用完记得调用remove方法释放
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