1. 概述

本文主要分享 RoutePredicateFactory 路由谓语工厂。

RoutePredicateFactory 涉及到的类在 org.springframework.cloud.gateway.handler.predicate 包下，如下图：

Spring Cloud Gateway 创建 Route 对象时，使用 RoutePredicateFactory 创建 Predicate 对象。Predicate 对象可以赋值给 Route.predicate 属性，用于匹配请求对应的 Route 。

2. RoutePredicateFactory

org.springframework.cloud.gateway.handler.predicate.RoutePredicateFactory ，路由谓语工厂接口。代码如下：

@FunctionalInterface
public interface RoutePredicateFactory extends ArgumentHints {

    String PATTERN_KEY = "pattern";

	Predicate<ServerWebExchange> apply(Tuple args);

	default String name() {
		return NameUtils.normalizePredicateName(getClass());
	}

}

#name() 默认方法，调用 NameUtils#normalizePredicateName(Class) 方法，获得 RoutePredicateFactory 的名字。该方法截取类名前半段，例如 QueryRoutePredicateFactory 的结果为 Query 。点击链接查看该方法。
#apply() 接口方法，创建 Predicate 。
继承 org.springframework.cloud.gateway.support.ArgumentHints 接口，在《Spring-Cloud-Gateway 源码解析 —— 路由（2.2）之 RouteDefinitionRouteLocator 路由配置》「2.4 获得 Tuple」有使用到它的代码。

RoutePredicateFactory 实现类如下图：

下面我们一个一个 RoutePredicateFactory 实现类理解。代码比较多，实际也比较简单。

另外，org.springframework.cloud.gateway.handler.predicate.RoutePredicates ，RoutePredicates 工厂，其调用 RoutePredicateFactory 接口的实现类，创建各种 Predicate 。

3. AfterRoutePredicateFactory

Route 匹配：请求时间满足在配置时间之后。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: after_route
        uri: http://example.org
        predicates:
        - After=2017-01-20T17:42:47.789-07:00[America/Denver]

RoutePredicates 方法：#after(ZonedDateTime) 。
代码：

1: public class AfterRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	public static final String DATETIME_KEY = "datetime";
 4: 
 5: 	@Override
 6: 	public List<String> argNames() {
 7: 		return Collections.singletonList(DATETIME_KEY);
 8: 	}
 9: 
10: 	@Override
11: 	public Predicate<ServerWebExchange> apply(Tuple args) {
12: 		Object value = args.getValue(DATETIME_KEY);
13: 		final ZonedDateTime dateTime = BetweenRoutePredicateFactory.getZonedDateTime(value);
14: 
15: 		return exchange -> {
16: 			final ZonedDateTime now = ZonedDateTime.now();
17: 			return now.isAfter(dateTime);
18: 		};
19: 	}
20: 
21: }

- Tulpe 参数：datetime 。
第 13 行：调用 BetweenRoutePredicateFactory#getZonedDateTime(value) 方法，解析配置的时间值，在「5. BetweenRoutePredicateFactory」详细解析。

4. BeforeRoutePredicateFactory

Route 匹配：请求时间满足在配置时间之前。
RoutePredicates 方法：#before(ZonedDateTime) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: before_route
        uri: http://example.org
        predicates:
        - Before=2017-01-20T17:42:47.789-07:00[America/Denver]

代码：

1: public class BeforeRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	public static final String DATETIME_KEY = "datetime";
 4: 
 5: 	@Override
 6: 	public List<String> argNames() {
 7: 		return Collections.singletonList(DATETIME_KEY);
 8: 	}
 9: 
10: 	@Override
11: 	public Predicate<ServerWebExchange> apply(Tuple args) {
12: 		Object value = args.getValue(DATETIME_KEY);
13: 		final ZonedDateTime dateTime = BetweenRoutePredicateFactory.getZonedDateTime(value);
14: 
15: 		return exchange -> {
16: 			final ZonedDateTime now = ZonedDateTime.now();
17: 			return now.isBefore(dateTime);
18: 		};
19: 	}
20: 
21: }

- Tulpe 参数：datetime 。
第 13 行：调用 BetweenRoutePredicateFactory#getZonedDateTime(value) 方法，解析配置的时间值，在「5. BetweenRoutePredicateFactory」详细解析。

5. BetweenRoutePredicateFactory

Route 匹配：请求时间满足在配置时间之间。
RoutePredicates 方法：#between(ZonedDateTime, ZonedDateTime) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: between_route
        uri: http://example.org
        predicates:
        - Betweeen=2017-01-20T17:42:47.789-07:00[America/Denver], 2017-01-21T17:42:47.789-07:00[America/Denver]

代码：

1: public class BetweenRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	public static final String DATETIME1_KEY = "datetime1";
 4: 	public static final String DATETIME2_KEY = "datetime2";
 5: 
 6: 	@Override
 7: 	public Predicate<ServerWebExchange> apply(Tuple args) {
 8: 		//TODO: is ZonedDateTime the right thing to use?
 9: 		final ZonedDateTime dateTime1 = getZonedDateTime(args.getValue(DATETIME1_KEY));
10: 		final ZonedDateTime dateTime2 = getZonedDateTime(args.getValue(DATETIME2_KEY));
11: 		Assert.isTrue(dateTime1.isBefore(dateTime2), args.getValue(DATETIME1_KEY) +
12: 				" must be before " + args.getValue(DATETIME2_KEY));
13: 
14: 		return exchange -> {
15: 			final ZonedDateTime now = ZonedDateTime.now();
16: 			return now.isAfter(dateTime1) && now.isBefore(dateTime2);
17: 		};
18: 	}
19: 
20: 	public static ZonedDateTime getZonedDateTime(Object value) {
21: 		ZonedDateTime dateTime;
22: 		if (value instanceof ZonedDateTime) {
23: 			dateTime = ZonedDateTime.class.cast(value);
24: 		} else {
25: 			dateTime = parseZonedDateTime(value.toString());
26: 		}
27: 		return dateTime;
28: 	}
29: 
30: 	public static ZonedDateTime parseZonedDateTime(String dateString) {
31: 		ZonedDateTime dateTime;
32: 		try {
33: 			// 数字
34: 			long epoch = Long.parseLong(dateString);
35: 			dateTime = Instant.ofEpochMilli(epoch).atOffset(ZoneOffset.ofTotalSeconds(0))
36: 					.toZonedDateTime();
37: 		} catch (NumberFormatException e) {
38: 			// 字符串
39: 			// try ZonedDateTime instead
40: 			dateTime = ZonedDateTime.parse(dateString);
41: 		}
42: 
43: 		return dateTime;
44: 	}
45: 
46: }

- Tulpe 参数：datetime1 / datetime2 。
第 20 至 44 行：解析配置的时间值。
第 22 至 23 行：当值类型为 ZonedDateTime 。主要使用 Java / Kotlin 配置 Route 时，例如 RoutePredicates#between(ZonedDateTime, ZonedDateTime) 。
第 33 至 36 行：当值类型为 Long 。例如配置文件 1511795602765。
当 38 至 41 行：当值类型为 String 。例如配置文件里 2017-01-20T17:42:47.789-07:00[America/Denver] 。

6. CookieRoutePredicateFactory

Route 匹配：请求指定 Cookie 正则匹配指定值。
RoutePredicates 方法：#cookie(String， String) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: cookie_route
        uri: http://example.org
        predicates:
        - Cookie=chocolate, ch.p

代码：

1: public class CookieRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	public static final String NAME_KEY = "name";
 4: 	public static final String REGEXP_KEY = "regexp";
 5: 
 6: 	@Override
 7: 	public List<String> argNames() {
 8: 		return Arrays.asList(NAME_KEY, REGEXP_KEY);
 9: 	}
10: 
11: 	@Override
12: 	public Predicate<ServerWebExchange> apply(Tuple args) {
13: 		String name = args.getString(NAME_KEY);
14: 		String regexp = args.getString(REGEXP_KEY);
15: 
16: 		return exchange -> {
17: 			List<HttpCookie> cookies = exchange.getRequest().getCookies().get(name);
18: 			for (HttpCookie cookie : cookies) {
19: 				// 正则匹配
20: 				if (cookie.getValue().matches(regexp)) {
21: 					return true;
22: 				}
23: 			}
24: 			return false;
25: 		};
26: 	}
27: }

- Tulpe 参数：name / regexp 。
第 20 行：指定 Cookie 正则匹配指定值。

7. HeaderRoutePredicateFactory

Route 匹配：请求指定 Cookie 正则匹配指定值。
RoutePredicates 方法：#header(String， String) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: header_route
        uri: http://example.org
        predicates:
        - Header=X-Request-Id, \d+

代码：

1: public class HeaderRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	public static final String HEADER_KEY = "header";
 4: 	public static final String REGEXP_KEY = "regexp";
 5: 
 6: 	@Override
 7: 	public List<String> argNames() {
 8: 		return Arrays.asList(HEADER_KEY, REGEXP_KEY);
 9: 	}
10: 
11: 	@Override
12: 	public Predicate<ServerWebExchange> apply(Tuple args) {
13: 		String header = args.getString(HEADER_KEY);
14: 		String regexp = args.getString(REGEXP_KEY);
15: 
16: 		return exchange -> {
17: 			List<String> values = exchange.getRequest().getHeaders().get(header);
18: 			for (String value : values) {
19: 				// 正则匹配
20: 				if (value.matches(regexp)) {
21: 					return true;
22: 				}
23: 			}
24: 			return false;
25: 		};
26: 	}
27: }

- Tulpe 参数：header / regexp 。
第 20 行：指定 Header 正则匹配指定值。

8. HostRoutePredicateFactory

Route 匹配：请求 Host 匹配指定值。
RoutePredicates 方法：#host(String) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: host_route
        uri: http://example.org
        predicates:
        - Host=**.somehost.org

代码：

1: public class HostRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	private PathMatcher pathMatcher = new AntPathMatcher(".");
 4: 
 5: 	public void setPathMatcher(PathMatcher pathMatcher) {
 6: 		this.pathMatcher = pathMatcher;
 7: 	}
 8: 
 9: 	@Override
10: 	public List<String> argNames() {
11: 		return Collections.singletonList(PATTERN_KEY);
12: 	}
13: 
14: 	@Override
15: 	public Predicate<ServerWebExchange> apply(Tuple args) {
16: 		String pattern = args.getString(PATTERN_KEY);
17: 
18: 		return exchange -> {
19: 			String host = exchange.getRequest().getHeaders().getFirst("Host");
20: 			// 匹配
21: 			return this.pathMatcher.match(pattern, host);
22: 		};
23: 	}
24: }

- Tulpe 参数：pattern 。
pathMatcher 属性，路径匹配器，默认使用 org.springframework.util.AntPathMatcher 。通过 #setPathMatcher(PathMatcher) 方法，可以重新设置。
第 21 行：请求路径匹配指定值。

9. MethodRoutePredicateFactory

Route 匹配：请求 Method 匹配指定值。
RoutePredicates 方法：#method(String) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: method_route
        uri: http://example.org
        predicates:
        - Method=GET

代码：

1: public class MethodRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	public static final String METHOD_KEY = "method";
 4: 
 5: 	@Override
 6: 	public List<String> argNames() {
 7: 		return Arrays.asList(METHOD_KEY);
 8: 	}
 9: 
10: 	@Override
11: 	public Predicate<ServerWebExchange> apply(Tuple args) {
12: 		String method = args.getString(METHOD_KEY);
13: 		return exchange -> {
14: 			HttpMethod requestMethod = exchange.getRequest().getMethod();
15: 			// 正则匹配
16: 			return requestMethod.matches(method);
17: 		};
18: 	}
19: }

- Tulpe 参数：method 。
第 16 行：请求 Method 匹配指定值。

10. PathRoutePredicateFactory

Route 匹配：请求 Path 匹配指定值。
RoutePredicates 方法：#path(String, String) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: host_route
        uri: http://example.org
        predicates:
        - Path=/foo/{segment}

代码：

1: public class PathRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	private PathPatternParser pathPatternParser = new PathPatternParser();
 4: 
 5: 	public void setPathPatternParser(PathPatternParser pathPatternParser) {
 6: 		this.pathPatternParser = pathPatternParser;
 7: 	}
 8: 
 9: 	@Override
10: 	public List<String> argNames() {
11: 		return Collections.singletonList(PATTERN_KEY);
12: 	}
13: 
14: 	@Override
15: 	public Predicate<ServerWebExchange> apply(Tuple args) {
16: 	    // 解析 Path ，创建对应的 PathPattern
17: 		String unparsedPattern = args.getString(PATTERN_KEY);
18: 		PathPattern pattern;
19: 		synchronized (this.pathPatternParser) {
20: 			pattern = this.pathPatternParser.parse(unparsedPattern);
21: 		}
22: 
23: 		return exchange -> {
24: 			PathContainer path = parsePath(exchange.getRequest().getURI().getPath());
25: 
26: 			// 匹配
27: 			boolean match = pattern.matches(path);
28: 			traceMatch("Pattern", pattern.getPatternString(), path, match);
29: 			if (match) {
30: 				// 解析 路径参数，例如 path=/foo/123 <=> /foo/{segment}
31: 				PathMatchInfo uriTemplateVariables = pattern.matchAndExtract(path);
32: 				exchange.getAttributes().put(URI_TEMPLATE_VARIABLES_ATTRIBUTE, uriTemplateVariables);
33: 				return true;
34: 			}
35: 			else {
36: 				return false;
37: 			}
38: 		};
39: 	}
40: }

- Tulpe 参数：pattern 。
pathPatternParser 属性，路径模式解析器。
第 17 至 21 行：解析配置的 Path ，创建对应的 PathPattern 。考虑到解析过程中的线程安全，此处使用 synchronized 修饰符，详见 PathPatternParser#parse(String) 方法的注释。
第 24 至 27 行：解析请求的 Path ，匹配配置的 Path 。
第 30 至 32 行：解析路径参数，设置到 ServerWebExchange.attributes 属性中，提供给后续的 GatewayFilter 使用。举个例子，当配置的 Path 为 /foo/{segment} ，请求的 Path 为 /foo/123 ，在此处打断点，结果如下图：

FROM 《Spring Cloud Gateway》
This predicate extracts the URI template variables (like segment defined in the example above) as a map of names and values and places it in the ServerWebExchange.getAttributes() with a key defined in PathRoutePredicate.URL_PREDICATE_VARS_ATTR. Those values are then available for use by GatewayFilter Factories

11. QueryRoutePredicateFactory

Route 匹配：请求 QueryParam 匹配指定值。
RoutePredicates 方法：#query(String, String) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: query_route
        uri: http://example.org
        predicates:
        - Query=baz
        - Query=foo, ba.

代码：

1: public class QueryRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	public static final String PARAM_KEY = "param";
 4: 	public static final String REGEXP_KEY = "regexp";
 5: 
 6: 	@Override
 7: 	public List<String> argNames() {
 8: 		return Arrays.asList(PARAM_KEY, REGEXP_KEY);
 9: 	}
10: 
11: 	@Override
12: 	public boolean validateArgs() {
13: 		return false;
14: 	}
15: 
16: 	@Override
17: 	public Predicate<ServerWebExchange> apply(Tuple args) {
18: 		validateMin(1, args);
19: 		String param = args.getString(PARAM_KEY);
20: 
21: 		return exchange -> {
22: 		    // 包含 参数
23: 			if (!args.hasFieldName(REGEXP_KEY)) {
24: 				// check existence of header
25: 				return exchange.getRequest().getQueryParams().containsKey(param);
26: 			}
27: 
28: 			// 正则匹配 参数
29: 			String regexp = args.getString(REGEXP_KEY);
30: 			List<String> values = exchange.getRequest().getQueryParams().get(param);
31: 			for (String value : values) {
32: 				if (value.matches(regexp)) {
33: 					return true;
34: 				}
35: 			}
36: 			return false;
37: 		};
38: 	}
39: }

- Tulpe 参数：param ( 必填 ) / regexp ( 选填 ) 。
第 18 行：调用 #validateMin(...) 方法，校验参数数量至少为 1 ，即 param 非空。
第 22 至 26 行：当 regexp 为空时，校验 param 对应的 QueryParam 存在。
第 28 至 35 行：当 regexp 非空时，请求 param 对应的 QueryParam 正则匹配指定值。
当 QueryParams 为空时，会报空指针 BUG 。

12. RemoteAddrRoutePredicateFactory

Route 匹配：请求来源 IP 在指定范围内。
RoutePredicates 方法：#remoteAddr(String...) 。
配置：

spring:
  cloud:
    gateway:
      routes:
      # =====================================
      - id: remoteaddr_route
        uri: http://example.org
        predicates:
        - RemoteAddr=192.168.1.1/24

代码：

1: public class RemoteAddrRoutePredicateFactory implements RoutePredicateFactory {
 2: 
 3: 	private static final Log log = LogFactory.getLog(RemoteAddrRoutePredicateFactory.class);
 4: 
 5: 	@Override
 6: 	public Predicate<ServerWebExchange> apply(Tuple args) {
 7: 		validate(1, args);
 8: 
 9: 		//
10: 		List<SubnetUtils> sources = new ArrayList<>();
11: 		if (args != null) {
12: 			for (Object arg : args.getValues()) {
13: 				addSource(sources, (String) arg);
14: 			}
15: 		}
16: 
17: 		return exchange -> {
18: 			InetSocketAddress remoteAddress = exchange.getRequest().getRemoteAddress();
19: 			if (remoteAddress != null) {
20: 				// 来源 IP
21: 				String hostAddress = remoteAddress.getAddress().getHostAddress();
22: 				String host = exchange.getRequest().getURI().getHost();
23: 				if (!hostAddress.equals(host)) {
24: 					log.warn("Remote addresses didn't match " + hostAddress + " != " + host);
25: 				}
26: 
27: 				//
28: 				for (SubnetUtils source : sources) {
29: 					if (source.getInfo().isInRange(hostAddress)) {
30: 						return true;
31: 					}
32: 				}
33: 			}
34: 
35: 			return false;
36: 		};
37: 	}
38: 
39: 	private void addSource(List<SubnetUtils> sources, String source) {
40: 		boolean inclusiveHostCount = false;
41: 		if (!source.contains("/")) { // no netmask, add default
42: 			source = source + "/32";
43: 		}
44: 		if (source.endsWith("/32")) {
45: 			//http://stackoverflow.com/questions/2942299/converting-cidr-address-to-subnet-mask-and-network-address#answer-6858429
46: 			inclusiveHostCount = true;
47: 		}
48: 		//TODO: howto support ipv6 as well?
49: 		SubnetUtils subnetUtils = new SubnetUtils(source);
50: 		subnetUtils.setInclusiveHostCount(inclusiveHostCount);
51: 		sources.add(subnetUtils);
52: 	}
53: }

Tulpe 参数：字符串数组。
第 7 行：调用 #validateMin(...) 方法，校验参数数量至少为 1 ，字符串数组非空。
第 10 至 15 行：使用 SubnetUtils 工具类，解析配置的值。
第 21 至 25 行：获得请求来源 IP 。
第 28 至 32 行：请求来源 IP 在指定范围内。

Spring-Cloud-Gateway 源码解析 —— 处理器 (3.1) 之 RoutePredicateFactory 路由谓语工厂