這里使用反射來實現(xiàn)參數(shù)添加悼潭，先貼代碼再膳、Controller接口代碼：

@GetMapping("/test")
public Mono<String> test(String param1, String param2, String param3) {
    return Mono.just(param1 + param2 + param3);
}

Filter代碼：

@Configuration
@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.REACTIVE)
public class TokenFilter implements WebFilter {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
        // 獲取Request
        ServerHttpResponse res = exchange.getResponse();
        // 獲取參數(shù)列表
        MultiValueMapAdapter params = (MultiValueMapAdapter) req.getQueryParams();

        try {
            // 反射獲取請求參數(shù)成員變量
            Field targetMap = params.getClass().getDeclaredField("targetMap");
            targetMap.setAccessible(true);
            // 創(chuàng)建一個新的可修改的Map
            Map newMap = new HashMap((Map) targetMap.get(params));
            // TODO: 這里插入需要的參數(shù)（value類型需要是List）
            newMap.put("param1", List.of("string1..."));
            newMap.put("param2", List.of("string2..."));
            newMap.put("param3", List.of("string3..."));
            // 將原有參數(shù)表替換
            targetMap.set(params, newMap);
        } catch (NoSuchFieldException | IllegalAccessException e) {
            e.printStackTrace();
        }
        return chain.filter(exchange);
    }

}

效果：

插入?yún)?shù)可能需要注意的幾點：
1帚豪、請求參數(shù)列表QueryParams的類型是MultiValueMapAdapter粹排，參數(shù)存放在成員變量targetMap中

public class MultiValueMapAdapter<K, V> implements MultiValueMap<K, V>, Serializable {

        private final Map<K, List<V>> targetMap;
        // ...

}

2胁艰、targetMap是一個final成員，使用原有的put()进宝，add()等操作都會報下面這個錯

java.lang.UnsupportedOperationException
Caused by: java.lang.UnsupportedOperationException: null
    at java.base/java.util.Collections$UnmodifiableMap.computeIfAbsent(Collections.java:1535)
    at org.springframework.util.MultiValueMapAdapter.add(MultiValueMapAdapter.java:66)
    // ...

3刻坊、targetMap的value需要是一個List，否則可能還會意外收獲這個錯

java.lang.ClassCastException: class java.lang.String cannot be cast to class java.util.List (java.lang.String and java.util.List are in module java.base of loader 'bootstrap')
    at org.springframework.util.MultiValueMapAdapter.get(MultiValueMapAdapter.java:132)
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
    |_ checkpoint ? springfox.boot.starter.autoconfigure.SwaggerUiWebFluxConfiguration$CustomWebFilter [DefaultWebFilterChain]
    // ...