问题
how wrote here http://developer.yahoo.com/performance/rules.html
For static components: implement "Never expire" policy by setting far future Expires header
i can gain performace avoiding http requests with a response as "304".
In official play! documentation i can see how set cache-controll directives, but how i can set far future Expires header?
best regards Nicola
edit: thanks for the replay now it work as well! here there are the classes:
conf/routes
# Static files
GET /assets/stylesheets/img/:name controllers.StaticFilesController.getBoostrapImg(name)
GET /assets/images/*name controllers.StaticFilesController.getImg(name)
GET /assets/stylesheets/*name controllers.StaticFilesController.getCss(name)
GET /assets/javascripts/*name controllers.StaticFilesController.getJs(name)
controllers/StaticFilesController.java
package controllers;
import org.apache.http.impl.cookie.DateUtils;
import java.util.*;
import play.mvc.*;
import services.FileName;
import play.*;
public class StaticFilesController extends Controller {
private static String nextYearString = StaticFilesController
.getNextYearAsString();
public static Result getImg(String path) {
FileName fileName = new FileName(path);
response().setHeader(EXPIRES, nextYearString);
response().setContentType("image/" + fileName.extension());
return ok(Play.application().getFile("/public/images/" + path));
}
public static Result getBoostrapImg(String path) {
FileName fileName = new FileName(path);
response().setHeader(EXPIRES, nextYearString);
response().setContentType("image/" + fileName.extension());
return ok(Play.application().getFile(
"/public/images/" + fileName.filename() + "."
+ fileName.extension()));
}
public static Result getCss(String path) {
response().setHeader(EXPIRES, nextYearString);
response().setContentType("text/css");
return ok(Play.application().getFile("/public/stylesheets/" + path));
}
public static Result getJs(String path) {
response().setHeader(EXPIRES, nextYearString);
response().setContentType("application/x-javascript");
return ok(Play.application().getFile("/public/javascripts/" + path));
}
private static String getNextYearAsString() {
Calendar calendar = new GregorianCalendar();
calendar.add(Calendar.YEAR, 1);
return DateUtils.formatDate(calendar.getTime());
}
}
services/FileName.java
package services;
/**
* This class assumes that the string used to initialize fullPath has a
* directory path, filename, and extension. The methods won't work if it
* doesn't.
*/
public class FileName {
private String fullPath;
private char pathSeparator, extensionSeparator;
public FileName(String str, char sep, char ext) {
fullPath = str;
pathSeparator = sep;
extensionSeparator = ext;
}
public FileName(String str)
{
fullPath = str;
pathSeparator = '/';
extensionSeparator = '.';
}
public String extension() {
int dot = fullPath.lastIndexOf(extensionSeparator);
return fullPath.substring(dot + 1);
}
public String filename() { // gets filename without extension
int dot = fullPath.lastIndexOf(extensionSeparator);
int sep = fullPath.lastIndexOf(pathSeparator);
return fullPath.substring(sep + 1, dot);
}
public String path() {
int sep = fullPath.lastIndexOf(pathSeparator);
return fullPath.substring(0, sep);
}
}
And the views/main.scala.html
@(skin: String)(content: Html)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>LibreTitan</title>
<link rel="stylesheet" media="screen" href="@routes.StaticFilesController.getCss("bootstrap/bootstrap.min.css")">
@if(skin != null && !skin.equals("")) {
<link rel="stylesheet" media="screen" href="@routes.StaticFilesController.getCss(skin+".min.css")">
}
<link rel="shortcut icon" type="image/png" href="@routes.StaticFilesController.getImg("favicon.png")">
<script async src="@routes.StaticFilesController.getJs("jquery-1.9.0.min.js")"></script>
<script async src="@routes.StaticFilesController.getJs("bootstrap.min.js")"></script>
</head>
<body>
<div class="container">
@content
</div>
</body>
</html>
回答1:
Never expire policy in this context means that should add Expire header to your response which date is in far future, for an example 10 years since now. You can easily do that in Play as described in the Manipulating the response doc. example:
public static Result index() {
response().setHeader(EXPIRES, "Thu, 16 Feb 2023 20:00:00 GMT");
return ok("<h1>Hello World!</h1>");
}
Of course instead giving expire date as a String you should use some method to calculate it dynamicaly, you can do that with org.joda.time.DateTime (available in Play) and its methods like: plusYears(int years). Most important is that should be formatted finally in RFC 1123 date format.
Edit, of course you can return different kinds of Results - also binary as described in the doc ('Results' section), to check all available options look into API of: play.mvc.Results it can be: ok(Content content) - typical when you render some view, ok(java.io.File content), ok(java.io.InputStream content), etc.
On the other hand...
I'd definitely recommend to DO NOT use Play for serving far future static contents (and any other static, public contents as well). Although you can do it easily, as described above, IMHO it's redundant waste of Play's resources as you need to handle all requests for any single image, script, style... whatever.
Consider using common... HTTP server for that job (nginx, lighthttpd, Apache) or even better some distributed CDN. In that case your app can concern on executing its logic instead of searching the stylesheets on the disk.
P.S. Remember that if you are using Play instead of HTTP server, for adding new static contents which are served from the /public folder you'll need to restart the application, so at least make sure that you are keeping them in some dedicated folder apart of application, so you can add/remove/replace them without stopping the application.
来源：https://stackoverflow.com/questions/14902855/far-future-expires-header-for-static-contents