实施 Webclient Mono 缓存

Question

我已经使用带有 Spring Cache 和 EhCache 实现的 spring mvc 应用程序实现了缓存，我在其中配置了 (.xml) 键类型和值类型，如下所示

    <key-type>java.lang.String</key-type>
    <value-type>my.object.returned</value-type>

但是现在我正在开发一个 Spring Webflux 应用程序，我正在调用第 3 方 API（Web 客户端调用）来获取一些数据。

为从 Webclient 返回的 Mono/Flux 数据实现缓存（在内存中）的最佳方法是什么。保留任何 Spring 缓存策略或 Project Reator 有一些本机缓存策略？

谢谢，

Answer 1

事实上，我有一个调用外部 API 的服务方法。

Mono<String> getExternalData (String input, ENUM enum) 

    Webclient.get
    ...

1. 我需要为相同的输入键（字符串、枚举）缓存结果值
2. 我想访问代码另一部分（缓存管理器）中的缓存值，以便在其他上下文中使用它。

Answer 2

您没有提供有关要缓存的内容的任何详细信息。基本上反应堆有多种.cache()方法用于缓存不同的策略。当您需要获取某些 API 的访问令牌并使用此令牌调用该 API 时，我将为您提供一些场景示例。比方说，这个令牌已经过期了，我们想缓存它并在它过期后刷新。

/**
 * Creating cached token mono
*/
Mono<Token> tokenMono = authenticate();

/**
 * Flow for calling mock api with cached token
 * Mock api called every 3 seconds with token. Token is valid for 10 seconds
 * Token will be refreshed after it is expired
 */
@Test
public void cacheCallTest() {
    Flux.interval(Duration.ofSeconds(3L))
            .flatMap(__ -> tokenMono)
            .flatMap(this::makeCall)
            .doOnNext(log::info)
            .blockLast();
}

/**
 * Mock auth api that returns cached token that will be cached until it is not expired
 * You can setup your caching strategy with .cache() methods, customize it with Duration and etc.
 */
public Mono<Token> authenticate() {
    return getToken()
            .cacheInvalidateIf(token ->
                    Instant.now().isAfter(token.validUntil)
            );
}

/**
 * Token supplier
 */
public Mono<Token> getToken() {
    return Mono.fromSupplier(() -> {
        Instant validUntil = Instant.now().plus(10, ChronoUnit.SECONDS);
        return new Token("token " + validUntil, validUntil);
    });
}

/**
 * Call mock api with the given token
 * @param token token
 */
public Mono<String> makeCall(Token token) {
    log.info("Making call with token {}", token.getToken());
    return Mono.defer(() -> Mono.just("Responded at  " + Instant.now()));
}

@Data
@AllArgsConstructor
public static class Token {

    private String token;
    private Instant validUntil;
}

这将弹出以下结果：

02:55:46.723 [parallel-1] INFO com.example.demo.FluxTest - Making call with token token 2023-01-22T22:55:56.710578Z
02:55:46.729 [parallel-1] INFO com.example.demo.FluxTest - Responded at  2023-01-22T22:55:46.728161Z
02:55:49.704 [parallel-1] INFO com.example.demo.FluxTest - Making call with token token 2023-01-22T22:55:56.710578Z
02:55:49.705 [parallel-1] INFO com.example.demo.FluxTest - Responded at  2023-01-22T22:55:49.705182Z
02:55:52.706 [parallel-1] INFO com.example.demo.FluxTest - Making call with token token 2023-01-22T22:55:56.710578Z
02:55:52.706 [parallel-1] INFO com.example.demo.FluxTest - Responded at  2023-01-22T22:55:52.706181Z
02:55:55.704 [parallel-1] INFO com.example.demo.FluxTest - Making call with token token 2023-01-22T22:55:56.710578Z
02:55:55.705 [parallel-1] INFO com.example.demo.FluxTest - Responded at  2023-01-22T22:55:55.705420Z
02:55:58.711 [parallel-1] INFO com.example.demo.FluxTest - Making call with token token 2023-01-22T22:56:08.711051Z
02:55:58.711 [parallel-1] INFO com.example.demo.FluxTest - Responded at  2023-01-22T22:55:58.711654Z
02:56:01.702 [parallel-1] INFO com.example.demo.FluxTest - Making call with token token 2023-01-22T22:56:08.711051Z
02:56:01.703 [parallel-1] INFO com.example.demo.FluxTest - Responded at  2023-01-22T22:56:01.703090Z
02:56:04.706 [parallel-1] INFO com.example.demo.FluxTest - Making call with token token 2023-01-22T22:56:08.711051Z
02:56:04.707 [parallel-1] INFO com.example.demo.FluxTest - Responded at  2023-01-22T22:56:04.706760Z
02:56:07.705 [parallel-1] INFO com.example.demo.FluxTest - Making call with token token 2023-01-22T22:56:08.711051Z
02:56:07.706 [parallel-1] INFO com.example.demo.FluxTest - Responded at  2023-01-22T22:56:07.706292Z

调用时注意token的时间戳。 希望能帮助到你。