Module java.net.http

Defines the HTTP Client and WebSocket APIs.

System properties used by the java.net.http API

The following is a list of system networking properties used by the java.net.http client implementation in the JDK. Any properties below that take a numeric value assume the default value if given a string that does not parse as a number. Unless otherwise specified below, all values can be set in the conf/net.properties file. In all cases, values can be specified as system properties on the command line, in which case, any value in conf/net.properties is overridden. No guarantee is provided that property values can be set programatically with System.setProperty(). Other implementations of this API may choose not to support these properties.

• jdk.httpclient.allowRestrictedHeaders (default: see below)
  A comma-separated list of normally restricted HTTP header names that users may set in HTTP requests or by user code in HttpRequest instances. By default, the following request headers are not allowed to be set by user code: connection, content-length, expect, host, and upgrade. You can override this behavior with this property. The names are case-insensitive and whitespace is ignored. Note that this property is intended for testing and not for real-world deployments. Protocol errors or other undefined behavior are likely to occur when using this property. There may be other headers that are restricted from being set depending on the context. This includes the "Authorization" header when the relevant HttpClient has an authenticator set. These restrictions cannot be overridden by this property.

• jdk.httpclient.bufsize (default: 16384 bytes or 16 kB)
  The size to use for internal allocated buffers in bytes.

• jdk.httpclient.connectionPoolSize (default: 0)
  The maximum number of connections to keep in the HTTP/1.1 keep alive cache. A value of 0 means that the cache is unbounded.

• jdk.httpclient.connectionWindowSize (default: 2^26)
  The HTTP/2 client connection window size in bytes. The maximum size is 2^31-1. This value cannot be smaller than the stream window size, which can be configured through the jdk.httpclient.windowsize system property.

• jdk.httpclient.disableRetryConnect (default: false)
  Whether automatic retry of connection failures is disabled. If false, then retries are attempted (subject to the retry limit).

• jdk.httpclient.enableAllMethodRetry (default: false)
  Whether it is permitted to automatically retry non-idempotent HTTP requests.

• jdk.httpclient.enablepush (default: 1)
  Whether HTTP/2 push promise is enabled. A value of 1 enables push promise; a value of 0 disables it.

• jdk.httpclient.hpack.maxheadertablesize (default: 16384 or 16 kB)
  The HTTP/2 client maximum HPACK header table size in bytes.

• jdk.httpclient.HttpClient.log (default: none)
  Enables high-level logging of various events through the Platform Logging API. The value contains a comma-separated list of any of the following items:

  • errors
  • requests
  • headers
  • content
  • frames
  • ssl
  • trace
  • channel
  
  You can append the frames item with a colon-separated list of any of the following items:
  • control
  • data
  • window
  • all
  
  Specifying an item adds it to the HTTP client's log. For example, if you specify the following value, then the Platform Logging API logs all possible HTTP Client events:
  "errors,requests,headers,frames:control:data:window,ssl,trace,channel"
  Note that you can replace control:data:window with all. The name of the logger is "jdk.httpclient.HttpClient", and all logging is at level INFO.

• jdk.httpclient.keepalive.timeout (default: 30)
  The number of seconds to keep idle HTTP connections alive in the keep alive cache. This property applies to both HTTP/1.1 and HTTP/2. The value for HTTP/2 can be overridden with the jdk.httpclient.keepalive.timeout.h2 property.

• jdk.httpclient.keepalive.timeout.h2 (default: see below)
  The number of seconds to keep idle HTTP/2 connections alive. If not set, then the jdk.httpclient.keepalive.timeout setting is used.

• jdk.httpclient.maxframesize (default: 16384 or 16kB)
  The HTTP/2 client maximum frame size in bytes. The server is not permitted to send a frame larger than this.

• jdk.httpclient.maxLiteralWithIndexing (default: 512)
  The maximum number of header field lines (header name and value pairs) that a client is willing to add to the HPack Decoder dynamic table during the decoding of an entire header field section. This is purely an implementation limit. If a peer sends a field section with encoding that exceeds this limit a ProtocolException will be raised. A value of zero or a negative value means no limit.

• jdk.httpclient.maxNonFinalResponses (default: 8)
  The maximum number of interim (non-final) responses that a client is prepared to accept on a request-response stream before the final response is received. Interim responses are responses with a status in the range [100, 199] inclusive. This is purely an implementation limit. If a peer sends a number of interim response that exceeds this limit before sending the final response, a ProtocolException will be raised. A value of zero or a negative value means no limit.

• jdk.httpclient.maxstreams (default: 100)
  The maximum number of HTTP/2 push streams that the client will permit servers to open simultaneously.

• jdk.httpclient.receiveBufferSize (default: operating system default)
  The HTTP client socket receive buffer size in bytes.

• jdk.httpclient.redirects.retrylimit (default: 5)
  The maximum number of attempts to send a HTTP request when redirected or any failure occurs for any reason.

• jdk.httpclient.websocket.writeBufferSize (default: 16384 or 16kB)
  The buffer size used by the web socket implementation for socket writes.

• jdk.httpclient.windowsize (default: 16777216 or 16 MB)
  The HTTP/2 client stream window size in bytes.

• jdk.httpclient.auth.retrylimit (default: 3)
  The number of attempts the Basic authentication filter will attempt to retry a failed authentication.

• jdk.httpclient.sendBufferSize (default: operating system default)
  The HTTP client socket send buffer size. Values less than or equal to zero are ignored.

• jdk.internal.httpclient.disableHostnameVerification (default: false)
  If true (or set to an empty string), hostname verification in SSL certificates is disabled. This is a system property only and not available in conf/net.properties. It is provided for testing purposes only.

• jdk.http.auth.proxying.disabledSchemes (default: see conf/net.properties)
  A comma separated list of HTTP authentication scheme names, that are disallowed for use by the HTTP client implementation, for HTTP proxying.

• jdk.http.auth.tunneling.disabledSchemes (default: see conf/net.properties)
  A comma separated list of HTTP authentication scheme names, that are disallowed for use by the HTTP client implementation, for HTTP CONNECT tunneling.

• jdk.http.maxHeaderSize (default: 393216 or 384kB)
  The maximum header field section size that the client is prepared to accept. This is computed as the sum of the size of the uncompressed header name, plus the size of the uncompressed header value, plus an overhead of 32 bytes for each field section line. If a peer sends a field section that exceeds this size a ProtocolException will be raised. This applies to all versions of the protocol. A value of zero or a negative value means no limit.