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CronetEngine.Builder

public static class CronetEngine.Builder extends Object

A builder for CronetEngines, which allows runtime configuration of CronetEngine. Configuration options are set on the builder and then build() is called to create the CronetEngine.

Nested Class Summary

class CronetEngine.Builder.LibraryLoader A class which provides a method for loading the cronet native library. 

Constant Summary

int HTTP_CACHE_DISABLED Setting to disable HTTP cache.
int HTTP_CACHE_DISK Setting to enable on-disk cache, including HTTP data.
int HTTP_CACHE_DISK_NO_HTTP Setting to enable on-disk cache, excluding HTTP data.
int HTTP_CACHE_IN_MEMORY Setting to enable in-memory HTTP cache, including HTTP data.

Public Constructor Summary

CronetEngine.Builder(Context context)
Constructs a CronetEngine.Builder object that facilitates creating a CronetEngine.

Public Method Summary

CronetEngine.Builder
addPublicKeyPins(String hostName, Set<byte[]> pinsSha256, boolean includeSubdomains, Date expirationDate)

Pins a set of public keys for a given host.

CronetEngine.Builder
addQuicHint(String host, int port, int alternatePort)
Adds hint that host supports QUIC.
CronetEngine
build()
Build a CronetEngine using this builder's configuration.
CronetEngine.Builder
enableBrotli(boolean value)
Sets whether Brotli compression is enabled.
CronetEngine.Builder
enableHttp2(boolean value)
Sets whether HTTP/2 protocol is enabled.
CronetEngine.Builder
enableHttpCache(int cacheMode, long maxSize)
Enables or disables caching of HTTP data and other information like QUIC server information.
CronetEngine.Builder
enablePublicKeyPinningBypassForLocalTrustAnchors(boolean value)
Enables or disables public key pinning bypass for local trust anchors.
CronetEngine.Builder
enableQuic(boolean value)
Sets whether QUIC protocol is enabled.
String
getDefaultUserAgent()
Constructs a User-Agent string including application name and version, system build version, model and id, and Cronet version.
CronetEngine.Builder
setLibraryLoader(CronetEngine.Builder.LibraryLoader loader)
Sets a CronetEngine.Builder.LibraryLoader to be used to load the native library.
CronetEngine.Builder
setStoragePath(String value)
Sets directory for HTTP Cache and Cookie Storage.
CronetEngine.Builder
setUserAgent(String userAgent)
Overrides the User-Agent header for all requests.

Inherited Method Summary

Constants

public static final int HTTP_CACHE_DISABLED

Setting to disable HTTP cache. Some data may still be temporarily stored in memory. Passed to enableHttpCache(int, long).

Constant Value: 0

public static final int HTTP_CACHE_DISK

Setting to enable on-disk cache, including HTTP data. setStoragePath(String) must be called prior to passing this constant to enableHttpCache(int, long).

Constant Value: 3

public static final int HTTP_CACHE_DISK_NO_HTTP

Setting to enable on-disk cache, excluding HTTP data. setStoragePath(String) must be called prior to passing this constant to enableHttpCache(int, long).

Constant Value: 2

public static final int HTTP_CACHE_IN_MEMORY

Setting to enable in-memory HTTP cache, including HTTP data. Passed to enableHttpCache(int, long).

Constant Value: 1

Public Constructors

public CronetEngine.Builder (Context context)

Constructs a CronetEngine.Builder object that facilitates creating a CronetEngine. The default configuration enables HTTP/2 and disables QUIC and the HTTP cache.

Parameters
context Android Context, which is used by CronetEngine.Builder to retrieve the application context. A reference to only the application context will be kept, so as to avoid extending the lifetime of context unnecessarily.

Public Methods

public CronetEngine.Builder addPublicKeyPins (String hostName, Set<byte[]> pinsSha256, boolean includeSubdomains, Date expirationDate)

Pins a set of public keys for a given host. By pinning a set of public keys, pinsSha256, communication with hostName is required to authenticate with a certificate with a public key from the set of pinned ones. An app can pin the public key of the root certificate, any of the intermediate certificates or the end-entry certificate. Authentication will fail and secure communication will not be established if none of the public keys is present in the host's certificate chain, even if the host attempts to authenticate with a certificate allowed by the device's trusted store of certificates.

Calling this method multiple times with the same host name overrides the previously set pins for the host.

More information about the public key pinning can be found in RFC 7469.

Parameters
hostName name of the host to which the public keys should be pinned. A host that consists only of digits and the dot character is treated as invalid.
pinsSha256 a set of pins. Each pin is the SHA-256 cryptographic hash of the DER-encoded ASN.1 representation of the Subject Public Key Info (SPKI) of the host's X.509 certificate. Use Certificate.getPublicKey() and Key.getEncoded() to obtain DER-encoded ASN.1 representation of the SPKI. Although, the method does not mandate the presence of the backup pin that can be used if the control of the primary private key has been lost, it is highly recommended to supply one.
includeSubdomains indicates whether the pinning policy should be applied to subdomains of hostName.
expirationDate specifies the expiration date for the pins.
Returns
  • the builder to facilitate chaining.
Throws
NullPointerException if any of the input parameters are null.
IllegalArgumentException if the given host name is invalid or pinsSha256 contains a byte array that does not represent a valid SHA-256 hash.

public CronetEngine.Builder addQuicHint (String host, int port, int alternatePort)

Adds hint that host supports QUIC. Note that enableHttpCache (HTTP_CACHE_DISK) is needed to take advantage of 0-RTT connection establishment between sessions.

Parameters
host hostname of the server that supports QUIC.
port host of the server that supports QUIC.
alternatePort alternate port to use for QUIC.
Returns
  • the builder to facilitate chaining.

public CronetEngine build ()

Build a CronetEngine using this builder's configuration.

Returns

public CronetEngine.Builder enableBrotli (boolean value)

Sets whether Brotli compression is enabled. If enabled, Brotli will be advertised in Accept-Encoding request headers. Defaults to disabled.

Parameters
value true to enable Brotli, false to disable.
Returns
  • the builder to facilitate chaining.

public CronetEngine.Builder enableHttp2 (boolean value)

Sets whether HTTP/2 protocol is enabled. Defaults to enabled.

Parameters
value true to enable HTTP/2, false to disable.
Returns
  • the builder to facilitate chaining.

public CronetEngine.Builder enableHttpCache (int cacheMode, long maxSize)

Enables or disables caching of HTTP data and other information like QUIC server information.

Parameters
cacheMode control location and type of cached data. Must be one of HTTP_CACHE_*.
maxSize maximum size in bytes used to cache data (advisory and maybe exceeded at times).
Returns
  • the builder to facilitate chaining.

public CronetEngine.Builder enablePublicKeyPinningBypassForLocalTrustAnchors (boolean value)

Enables or disables public key pinning bypass for local trust anchors. Disabling the bypass for local trust anchors is highly discouraged since it may prohibit the app from communicating with the pinned hosts. E.g., a user may want to send all traffic through an SSL enabled proxy by changing the device proxy settings and adding the proxy certificate to the list of local trust anchor. Disabling the bypass will most likly prevent the app from sending any traffic to the pinned hosts. For more information see 'How does key pinning interact with local proxies and filters?' at //www.chromium.org/Home/chromium-security/security-faq

Parameters
value true to enable the bypass, false to disable.
Returns
  • the builder to facilitate chaining.

public CronetEngine.Builder enableQuic (boolean value)

Sets whether QUIC protocol is enabled. Defaults to disabled. If QUIC is enabled, then QUIC User Agent Id containing application name and Cronet version is sent to the server.

Parameters
value true to enable QUIC, false to disable.
Returns
  • the builder to facilitate chaining.

public String getDefaultUserAgent ()

Constructs a User-Agent string including application name and version, system build version, model and id, and Cronet version.

Returns
  • User-Agent string.

public CronetEngine.Builder setLibraryLoader (CronetEngine.Builder.LibraryLoader loader)

Sets a CronetEngine.Builder.LibraryLoader to be used to load the native library. If not set, the library will be loaded using loadLibrary(String).

Parameters
loader LibraryLoader to be used to load the native library.
Returns
  • the builder to facilitate chaining.

public CronetEngine.Builder setStoragePath (String value)

Sets directory for HTTP Cache and Cookie Storage. The directory must exist.

NOTE: Do not use the same storage directory with more than one CronetEngine at a time. Access to the storage directory does not support concurrent access by multiple CronetEngines.

Parameters
value path to existing directory.
Returns
  • the builder to facilitate chaining.

public CronetEngine.Builder setUserAgent (String userAgent)

Overrides the User-Agent header for all requests. An explicitly set User-Agent header (set using addHeader(String, String)) will override a value set using this function.

Parameters
userAgent the User-Agent string to use for all requests.
Returns
  • the builder to facilitate chaining.