@ServletComponentScan導致的dofilter執行兩次

1.@ServletComponentScan用法
在 Spring Boot啓動類上使用@ServletComponentScan 註解後，使用@WebServlet、@WebFilter、@WebListener標記的 Servlet、Filter、Listener 就可以自動註冊到Servlet容器中，無需其他代碼。
2.錯誤用法示例：

package cn.rivamed.um.filter;

import cn.rivamed.common.exception.ExeceptionDto;
import cn.rivamed.common.util.Constants;
import cn.rivamed.entity.AccessToken;
import cn.rivamed.framework.common.BaseConstants;
import cn.rivamed.framework.common.config.PropertiesBean;
import cn.rivamed.service.OauthService;
import cn.rivamed.um.common.TokenUtils;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.SerializerFeature;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;

@Component
@ServletComponentScan
@WebFilter()
public class LoginFilter implements Filter {

	@Resource
	private OauthService oauthService;

	@Resource
	private TokenUtils tokenUtils;

	private String[] ignoreUrls = null;
	// 刷新患者的地址
	private static final String IGNORE_URL = PropertiesBean.getInstance()
			.getProperty("rivamed.security.cas.app-pattern.ignoring");

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		HttpServletResponse response2 = (HttpServletResponse) response;
		response2.setHeader("Access-Control-Allow-Origin","*");
		response2.setHeader("Access-Control-Allow-Credentials", "true");
		response2.setHeader("Access-Control-Allow-Methods", "POST, PUT, GET, OPTIONS, DELETE");
		response2.setHeader("Access-Control-Max-Age", "5000");
		response2.setHeader("Access-Control-Allow-Headers", "Origin, No-Cache, X-Requested-With, If-Modified-Since," +
				" Pragma, Last-Modified, Cache-Control, Expires, Content-Type, X-E4M-With,Authorization,Token,tokenId,tokenid");
		HttpServletRequest request2 = (HttpServletRequest) request;
		String tokenId = request2.getHeader("tokenId");

		for (String ignoreUrl : ignoreUrls) {
			if (request2.getRequestURI().contains(ignoreUrl)) {
				chain.doFilter(request, response2);
				return;
			}
		}
//		Long startTime=System.currentTimeMillis();
		AccessToken token = oauthService.findAccessToken(tokenId);
//		Long endTime=System.currentTimeMillis();
//		System.out.println(request2.getRequestURI()+"獲取token用時---used time---"+(endTime-startTime));
		if (null != token) {
			if (token.tokenExpired() && token.refreshTokenExpired()) {
				writeResponse(response2, Constants.LOGIN_EXPIRED);
				return;
			}
			if (token.tokenExpired() && !token.refreshTokenExpired()) {
				writeResponse(response2, Constants.TOKEN_EXPIRED);
				return;
			} else {
				tokenUtils.initRequestUserInfo(token);
				chain.doFilter(request, response2);
			}
		} else {
			writeResponse(response2, Constants.LOGIN_EXPIRED);
			return;
		}


	}

	private void writeResponse(ServletResponse response, String status) throws IOException {
		HttpServletResponse response2 = (HttpServletResponse) response;
		OutputStream outputStream = response2.getOutputStream();// 獲取
		ExeceptionDto dto = new ExeceptionDto();
		dto.setOpFlg(status);
		dto.setOperateSuccess(BaseConstants.OPERATE_FAIL);
		response2.setHeader("content-type", "application/json;charset=UTF-8");// 通過設置響應頭控制瀏覽器以UTF-8的編碼顯示數據，如果不加這句話，那麼瀏覽器顯示的將是亂碼
		byte[] bs = JSONObject.toJSONBytes(dto, SerializerFeature.EMPTY);
		outputStream.write(bs);// 使用OutputStream流向客戶端輸出字節數組
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		ignoreUrls = IGNORE_URL.split(",");
	}

	@Override
	public void destroy() {
	}

}

@Component、@ServletComponentScan、@WebFilter()這三個註解連用會導致doFilter方法執行兩次，解決方法就是將@ServletComponentScan註解去掉，這個註解不是在這裏的！