播放框架2.1 HTTP HEAD方法響應

Question

如何在Scala Play Framework 2.1上返回唯一的響應標頭（HTTP HEAD方法）？

Answer 1

您可以在GET路由旁邊添加HEAD路由，如下所示：

GET   /assertion                        controllers.Assertion.get
HEAD  /assertion                        controllers.Assertion.head

我想，在實現方法中，您可以調用GET方法並傳遞一個標志以禁止顯示主體。

Answer 2

返回EmptyContent作為內容怎么辦

     Action {
        ....
        Ok(EmptyContent())  
     }

Answer 3

不幸的是，有Java解決方案，但也許您會將其“轉換”為Scala，一般概念是：

• 捕獲HEAD請求將其發送到專用方法
• 方法autoHead(String originalPath)使用WebServices轉發參數發送GET請求，並僅返回響應狀態。
• 它添加了額外的標頭X_FORWARD_FROM_HEAD因此，如果您的操作在每次命中后將某些內容記錄到數據庫中，則可以避免HEAD請求。

碼：

/**
 * Tries to get headers of resource with WebServices and return headers only.
 *
 * @param originalPath Path of the resource
 * @return Headers for HEAD request
 * @throws IllegalAccessException
 */
public static Result autoHead(String originalPath) throws IllegalAccessException {


    WS.WSRequestHolder forwardedRequest = WS.url("http://" + request().host() + request().path());
    // this header will allow you to make additional choice i.e. avoid tracking the request or something else
    // see condition in index() action
    forwardedRequest.setHeader("X_FORWARD_FROM_HEAD", "true");

    // Forward original headers
    for (String header : request().headers().keySet()) {
        forwardedRequest.setHeader(header, request().getHeader(header));
    }

    // Forward original queryString
    for (String key : request().queryString().keySet()) {
        for (String val : request().queryString().get(key)) {
            forwardedRequest.setQueryParameter(key, val);
        }
    }

    // Call the same path but with GET
    WS.Response wsResponse = forwardedRequest.get().get();

    // Set returned headers to the response
    for (Field f : Http.HeaderNames.class.getFields()) {
        String headerName = f.get(null).toString();
        if (wsResponse.getHeader(headerName) != null) {
            response().setHeader(headerName, wsResponse.getHeader(headerName));
        }
    }

    return status(wsResponse.getStatus());
}

/**
 * Checks if request if forwarded from HEAD request
 *
 * @return true if 'X_FORWARD_FROM_HEAD' header exists and is set to true
 */
public static boolean forwardedFromHead() {
    return (request().getHeader("X_FORWARD_FROM_HEAD") != null && "true".equals(request().getHeader("X_FORWARD_FROM_HEAD")));
}

路線：

HEAD    /                  controllers.Application.autoHead(originalPath:String ?= "/")
HEAD    /*originalPath     controllers.Application.autoHead(originalPath:String)