为 Play 编写自定义过滤器！2.2 Java [英] Writing custom filters for Play! 2.2 in Java

问题描述

我有一个简单的场景:自动为每个 HTTP 响应添加一个响应头；我想用 Java 来做这件事.

I have a simple scenario: automatically add a response header to every HTTP response; and I want to do this in Java.

看src/play-filters-helpers/src/main/java/play/filters/*，有Actions 可以用作注释.我想避免将 @AddMyHeader 添加到每个处理程序.

Looking at src/play-filters-helpers/src/main/java/play/filters/*, there are examples of Actions which can be applied as annotations. I'd like to avoid adding @AddMyHeader to every handler.

查看 src/play-filters-helpers/src/中的 Scala 过滤器main/scala/play/filters/* 和 GzipFilter 特别是，我看到了一个清晰的机制，但我对 Scala 不够熟悉，无法推断到 Java.

Looking at the Scala Filters in src/play-filters-helpers/src/main/scala/play/filters/* and GzipFilter specifically, I see a clear mechanism, but I'm not familiar enough with Scala to extrapolate to Java.

那么:我从这里去哪里?

So: where do I go from here?

推荐答案

遗憾的是，目前还没有一种从 Java 创建和使用过滤器的好方法.但是您可以使用 Scala 轻松完成所需的工作.

Unfortunately there isn't a good way to create and use Filters from Java yet. But you can do what you need pretty easily with Scala.

创建一个新文件 app/filters/AddResponseHeader.scala 包含:

Create a new file app/filters/AddResponseHeader.scala containing:

package filters

import play.api.mvc._
import scala.concurrent.Future
import scala.concurrent.ExecutionContext.Implicits.global

object AddResponseHeader extends Filter {
  def apply(f: (RequestHeader) => Future[SimpleResult])(rh: RequestHeader): Future[SimpleResult] = {
    val result = f(rh)
    result.map(_.withHeaders("FOO" -> "bar"))
  }
}

并创建一个新文件 app/Global.scala 包含:

And create a new file app/Global.scala containing:

import filters.AddResponseHeader
import play.api.mvc.WithFilters

object Global extends WithFilters(AddResponseHeader)

这应该对每个响应应用一个新的响应头.

That should apply a new response header to every response.

UPDATE:有一种方法可以在 Global.java 文件中使用它:

UPDATE: There is a way to use this in a Global.java file:

@Override
public <T extends EssentialFilter> Class<T>[] filters() {
    return new Class[] {AddResponseHeader.class};
}

并将上面的 object AddResponseHeader 更改为 class AddResponseHeader.

And also change the object AddResponseHeader above to class AddResponseHeader.

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