seata http rpc获取全局事务xid源码解析

• 事务传播拦截器
  从请求header中获取远程调用xid
  io.seata.integration.http.TransactionPropagationInterceptor

public class TransactionPropagationInterceptor extends HandlerInterceptorAdapter {


    private static final Logger LOGGER = LoggerFactory.getLogger(TransactionPropagationInterceptor.class);


    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        String xid = RootContext.getXID();
        String rpcXid = request.getHeader(RootContext.KEY_XID);

        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug("xid in RootContext[{}] xid in HttpContext[{}]", xid, rpcXid);
        }
        if (xid == null && rpcXid != null) {
            RootContext.bind(rpcXid);
            if (LOGGER.isDebugEnabled()) {
                LOGGER.debug("bind[{}] to RootContext", rpcXid);
            }
        }

        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
        ModelAndView modelAndView) {
        if (RootContext.inGlobalTransaction()) {
            XidResource.cleanXid(request.getHeader(RootContext.KEY_XID));
        }
    }

}