在用spring cloud zuul做Filter的時候，訪問微服務出現跨域問題，在網上找了很多辦法：

zuul:
  ignored-headers: Access-Control-Allow-Credentials, Access-Control-Allow-Origin

方法1
於是在Filter裡面改程式碼解決了問題：
CloudFilter.java

@Component
public class CloudFilter extends ZuulFilter {

    @Override
    public String filterType() {
        return
 
 "pre";
    }

    @Override
    public int filterOrder() {
        return 0;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() {
        RequestContext ctx = RequestContext.getCurrentContext();

            HttpServletResponse response = ctx.getResponse();
            response.addHeader("Access-Control-Allow-Origin"
 
, "*");
            response.setContentType("application/json");
            response.setCharacterEncoding("UTF-8");
            response.setContentType("text/html;charset=UTF-8");
}

}

方法2
在@EnableZuulProxy註解裡的Class類加入下面這個Bean:
用到CorsFilter這個類，需要import org.springframework.web.filter.CorsFilter;

    @Bean
 

    public CorsFilter corsFilter() {
        final UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        final CorsConfiguration config = new CorsConfiguration();
        config.setAllowCredentials(true);
        config.addAllowedOrigin("*");
        config.addAllowedHeader("*");
        config.addAllowedMethod("OPTIONS");
        config.addAllowedMethod("HEAD");
        config.addAllowedMethod("GET");
        config.addAllowedMethod("PUT");
        config.addAllowedMethod("POST");
        config.addAllowedMethod("DELETE");
        config.addAllowedMethod("PATCH");
        source.registerCorsConfiguration("/**", config);
        return new CorsFilter(source);
    }

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