玩 2.5：在自定义 http 操作中获取响应正文

Question

我正在尝试创建自定义 http 操作 (https://playframework.com/documentation/2.5.x/JavaActionsComposition) 以使用 Play 2.5.0 Java 记录请求和响应主体。这是我到目前为止得到的：

public class Log extends play.mvc.Action.Simple {

    public CompletionStage<Result> call(Http.Context ctx) {
        CompletionStage<Result> response = delegate.call(ctx);
        //request body is fine
        System.out.println(ctx.request().body().asText())
        //how to get response body string here while also not sabotaging http response flow of the framework?
        //my guess is it should be somehow possible to access it below?
        response.thenApply( r -> {
            //???
            return null;
        });
        return response;
    }

}

Answer 1

日志记录通常被认为是一个跨领域的特性。在这种情况下，在 Play 中执行此操作的首选方法是使用过滤器：

The filter API is intended for cross cutting concerns that are applied indiscriminately to all routes. For example, here are some common use cases for filters:

Logging/metrics collection

GZIP encoding

Security headers

这对我有用：

import java.util.concurrent.CompletionStage;
import java.util.function.Function;
import javax.inject.Inject;
import akka.stream.*;
import play.Logger;
import play.mvc.*;

public class LoggingFilter extends Filter {

    Materializer mat;

    @Inject
    public LoggingFilter(Materializer mat) {
        super(mat);
        this.mat = mat;
    }

    @Override
    public CompletionStage<Result> apply(
            Function<Http.RequestHeader, CompletionStage<Result>> nextFilter,
            Http.RequestHeader requestHeader) {
        long startTime = System.currentTimeMillis();
        return nextFilter.apply(requestHeader).thenApply(result -> {
            long endTime = System.currentTimeMillis();
            long requestTime = endTime - startTime;

            Logger.info("{} {} took {}ms and returned {}",
                requestHeader.method(), requestHeader.uri(), requestTime, result.status());
            akka.util.ByteString body = play.core.j.JavaResultExtractor.getBody(result, 10000l, mat);
            Logger.info(body.decodeString("UTF-8"));

            return result.withHeader("Request-Time", "" + requestTime);
        });
    }
}

它在做什么？

首先，这会创建一个新的过滤器，它可以与您可能拥有的其他过滤器一起使用。为了获得响应的主体，我们实际上使用 nextFilter - 一旦我们有了响应，我们就可以得到主体。

从 Play 2.5 开始 Akka Streams 是首选武器。这意味着一旦你使用 JavaResultExtractor，你将得到一个 ByteString，然后你必须对其进行解码以获得下面的真实字符串。

请记住，在您正在创建的 Action 中复制此逻辑应该没有问题。由于 post.

顶部所述的原因，我刚刚选择了带有 Filter 的选项

玩 2.5：在自定义 http 操作中获取响应正文

Play 2.5: get response body in custom http action

java

http

playframework

playframework-2.0

playframework-2.5