Spring Cloud Netflix Zuul

1. FilterConstants

在org.springframework.cloud.netflix.zuul.filters.support.FilterConstants中，可以看到Zuul定义了一些默认Filter的执行顺序。

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public final class FilterConstants {
  
  //省略...
  
  // ORDER constants -----------------------------------

	/**
	 * Filter Order for {@link DebugFilter#filterOrder()}.
	 */
	public static final int DEBUG_FILTER_ORDER = 1;

	/**
	 * Filter Order for
	 * {@link org.springframework.cloud.netflix.zuul.filters.pre.FormBodyWrapperFilter#filterOrder()}.
	 */
	public static final int FORM_BODY_WRAPPER_FILTER_ORDER = -1;

	/**
	 * Filter Order for
	 * {@link org.springframework.cloud.netflix.zuul.filters.pre.PreDecorationFilter}.
	 */
	public static final int PRE_DECORATION_FILTER_ORDER = 5;

	/**
	 * Filter Order for
	 * {@link org.springframework.cloud.netflix.zuul.filters.route.RibbonRoutingFilter#filterOrder()}.
	 */
	public static final int RIBBON_ROUTING_FILTER_ORDER = 10;

	/**
	 * Filter Order for
	 * {@link org.springframework.cloud.netflix.zuul.filters.post.SendErrorFilter#filterOrder()}.
	 */
	public static final int SEND_ERROR_FILTER_ORDER = 0;

	/**
	 * Filter Order for {@link SendForwardFilter#filterOrder()}.
	 */
	public static final int SEND_FORWARD_FILTER_ORDER = 500;

	/**
	 * Filter Order for
	 * {@link org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter#filterOrder()}.
	 */
	public static final int SEND_RESPONSE_FILTER_ORDER = 1000;

	/**
	 * Filter Order for
	 * {@link org.springframework.cloud.netflix.zuul.filters.route.SimpleHostRoutingFilter#filterOrder()}.
	 */
	public static final int SIMPLE_HOST_ROUTING_FILTER_ORDER = 100;

	/**
	 * filter order for {@link Servlet30WrapperFilter#filterOrder()}.
	 */
	public static final int SERVLET_30_WRAPPER_FILTER_ORDER = -2;

	/**
	 * filter order for
	 * {@link org.springframework.cloud.netflix.zuul.filters.pre.ServletDetectionFilter#filterOrder()}.
	 */
	public static final int SERVLET_DETECTION_FILTER_ORDER = -3;
  
  //省略...
  
}

2. 默认Filter

pre

  • ServletDetectionFilter (-3)：检测请求是通过DispatcherServlet还是ZuulServlet 运行的.
  • Servlet30WrapperFilter(-2)：对Servlet3.0环境的包装器过滤
  • FormBodyWrapperFilter(-1)：为下游服务解析表单数据并重新编码.仅在content-type为application/x-www-form-urlencoded或者multipart/form-data时生效.
  • DebugFilter(1)：如果设置了“debug”请求参数，则将{@link RequestContext}调试属性设置为true
  • PreDecorationFilter(5)：根据提供的{@link RouteLocator}确定路由的位置和方式。 *还为下游请求设置各种代理相关的标头

route

  • RibbonRoutingFilter(10)：使用Ribbon，Hystrix和可插入的http客户端发送请求。
  • SimpleHostRoutingFilter(100)：通过过apache http clients向预定的url发送请求.
  • SendForwardFilter(500)：使用requestDispatcher 转发请求.

post

  • SendResponseFilter(1000)：将代理请求的响应写入当前响应。

error

  • SendErrorFilter(0)：默认情况下转发到/error路径,如果RequestContext.getThrowable()不是空。