How to configure spring's RestTemplate to make http2 requests?

Question

I have a RestClient calling GET Requests to a spring service(server), that server is accepting HTTP2 requests and i'm getting 302 as response. How to send Http2 requests using spring RestTemplate.

Exception in thread "main" org.springframework.web.client.ResourceAccessException: I/O error on GET request for "https://example.com/static/mobile/get-token": unexpected end of stream on Connection{domain.com:443, proxy=DIRECT hostAddress=example.com cipherSuite=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 protocol=http/1.1}; nested exception is java.io.IOException: unexpected end of stream on Connection{example.com:443, proxy=DIRECT hostAddress=example.com cipherSuite=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 protocol=http/1.1}
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:732)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:680)
at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:600)
at com.domain.Sample.main(Sample.java:45)
Caused by: java.io.IOException: unexpected end of stream on Connection{example.com:443, proxy=DIRECT hostAddress=example.com cipherSuite=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 protocol=http/1.1}
    at okhttp3.internal.http1.Http1Codec.readResponseHeaders(Http1Codec.java:205)
    at okhttp3.internal.http.CallServerInterceptor.intercept(CallServerInterceptor.java:88)
    at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
    at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:45)
    at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
    at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
    at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:93)
    at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
    at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
    at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93)
    at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
    at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:125)
    at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
    at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
    at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:200)
    at okhttp3.RealCall.execute(RealCall.java:77)
    at org.springframework.http.client.OkHttp3ClientHttpRequest.executeInternal(OkHttp3ClientHttpRequest.java:73)
    at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
    at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:723)
    ... 3 more

Answer 1

Use OkHttp3ClientHttpRequestFactory.

RestTemplate http2Template = new RestTemplate(new OkHttp3ClientHttpRequestFactory());