如何配置Lagom框架以使用CORS

Question

如何配置Lagom框架以处理CORS请求(方法请求"options"(。

Answer 1

我已经用这种方式在lagom中为我的一个项目启用了CORS。

在服务类中定义一个方法来处理OPTIONS调用。

ServiceCall<NotUsed, Done> options();

在服务impl类中实现该方法。

@Override
public ServiceCall<NotUsed, Done> options() {
return request -> CompletableFuture.completedFuture(Done.getInstance());
}

在描述符中定义选项调用。举个例子，假设实际呼叫是

GET /api/v0.1/user

服务描述符应该如下所示：

@Override
default Descriptor descriptor() {
// @formatter:off
return named("notification").withCalls(
restCall(Method.GET, "/api/v0.1/user", this::getUser),
restCall(Method.OPTIONS, "/api/v0.1/user", this::options)
).withAutoAcl(true).withHeaderFilter(new CORSHeaderFilter());
// @formatter:on
}

请注意，它有一个使用连接的标题过滤器

.withHeaderFilter(new CORSHeaderFilter()) 

CORSHeaderFilter类应该是这样的。

import com.lightbend.lagom.javadsl.api.transport.HeaderFilter;
import com.lightbend.lagom.javadsl.api.transport.Method;
import com.lightbend.lagom.javadsl.api.transport.RequestHeader;
import com.lightbend.lagom.javadsl.api.transport.ResponseHeader;
public class CORSHeaderFilter implements HeaderFilter {
@Override
public RequestHeader transformClientRequest(RequestHeader request) {
return request;
}
@Override
public RequestHeader transformServerRequest(RequestHeader request) {
return request;
}
@Override
public ResponseHeader transformServerResponse(ResponseHeader response, RequestHeader request) {
ResponseHeader modifiedResponse = response.withHeader("Access-Control-Allow-Origin", "*");
if (Method.OPTIONS.equals(request.method())) {
modifiedResponse = modifiedResponse.withStatus(204).withHeader("Access-Control-Allow-Headers",
"Authorization,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With" +
",If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range").
withHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS, PATCH").
withHeader("Access-Control-Max-Age", "1728000");
}
return modifiedResponse;
}
@Override
public ResponseHeader transformClientResponse(ResponseHeader response, RequestHeader request) {
ResponseHeader modifiedResponse = response.withHeader("Access-Control-Allow-Origin", "*");
if (Method.OPTIONS.equals(request.method())) {
modifiedResponse = modifiedResponse.withStatus(204).withHeader("Access-Control-Allow-Headers",
"Authorization,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With" +
",If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range").
withHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS, PATCH").
withHeader("Access-Control-Max-Age", "1728000");
}
return modifiedResponse;
}
}

每当添加新端点时，请确保也添加其OPTIONS版本。

Answer 2

要允许用Java编写的Lagom服务与CORS一起工作，您需要在每次播放时实现CORS过滤器：

package example.service.impl

import play.filters.cors.CORSFilter;
import play.http.DefaultHttpFilters;
import javax.inject.Inject;
// See https://playframework.com/documentation/2.5.x/CorsFilter
public class MyCORSFilter extends DefaultHttpFilters {
@Inject
public MyCORSFilter(CORSFilter corsFilter) {
super(corsFilter);
}
}

然后在application.conf中，您需要添加过滤器：

play.http.filters = "example.service.impl.MyCORSFilter"
// To properly setup the CORSFilter, please refer to https://playframework.com/documentation/2.5.x/CorsFilter
// This example is only meant to show what's required for Lagom to use CORS.
play.filters.cors {
// review the values of all these settings to fulfill your needs. These values are not meant for production.
pathPrefixes = ["/api"]
allowedOrigins = null
allowedHttpMethods = null
allowedHttpHeaders = null
exposedHeaders = []
supportsCredentials = false
preflightMaxAge = 6 hour
}

有关更多信息，请参阅示例CORS服务和Play文档。