CronetEngine.Builder

public static final int HTTP_CACHE_DISABLED = 0

Setting to disable HTTP cache. Some data may still be temporarily stored in memory. Passed to enableHttpCache.

public static final int HTTP_CACHE_DISK = 3

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

public static final int HTTP_CACHE_DISK_NO_HTTP = 2

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

public static final int HTTP_CACHE_IN_MEMORY = 1

Setting to enable in-memory HTTP cache, including HTTP data. Passed to enableHttpCache.

protected JSONObject mParsedExperimentalOptions

JSON representation of the experimental options.

public Builder(Context context)

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

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.

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.

public CronetEngine build()

Build a CronetEngine using this builder's configuration.

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.

public CronetEngine.Builder enableHttp2(boolean value)

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

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

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

public CronetEngine.Builder enableNetworkQualityEstimator(boolean value)

Enables the network quality estimator, which collects and reports measurements of round trip time (RTT) and downstream throughput at various layers of the network stack. After enabling the estimator, listeners of RTT and throughput can be added with addRttListener and addThroughputListener and removed with removeRttListener and removeThroughputListener. The estimator uses memory and CPU only when enabled.

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 likely 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 https://www.chromium.org/Home/chromium-security/security-faq

public CronetEngine.Builder enableQuic(boolean value)

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

public String getDefaultUserAgent()

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

@ConnectionMigrationOptions.Experimental
public CronetEngine.Builder setConnectionMigrationOptions(
    ConnectionMigrationOptions connectionMigrationOptions
)

Configures the behavior of connection migration. For more details, see documentation of ConnectionMigrationOptions and the individual methods of ConnectionMigrationOptions.Builder.

Only relevant if enableQuic is enabled.

@DnsOptions.Experimental
public CronetEngine.Builder setDnsOptions(DnsOptions dnsOptions)

Configures the behavior of hostname lookup. For more details, see documentation of DnsOptions and the individual methods of DnsOptions.Builder.

Only relevant if enableQuic is enabled.

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

Sets a LibraryLoader to be used to load the native library. If not set, the library will be loaded using loadLibrary.

public CronetEngine.Builder setProxyOptions(@NonNull ProxyOptions proxyOptions)

Configures proxying behavior. This affects, in different ways: connections establishment, UrlRequest and BidirectionalStream. For more details, refer to the documentation of Proxy.

This is not to be confused with proxy configuration that have been set up by: the user; or some enterprise profile configuration, or (most likely) some network autoconfiguration (e.g., Web Proxy Auto-Discovery Protocol). This is usually referred to as "system" proxy configuration. If present, respecting the system proxy configuration is often a requirement to obtain local and/or internet connectivity. CronetEngine already handles the system proxy configuration internally.

A proxy configuration defined via this API are refererred to as "app" proxy configuration. App and system proxy configuration are separate and, most importantly, differ. Currently, app and system proxy configurations are mutually exclusive: specifying ProxyOptions overrides the system proxy configuration, if present. This might cause connectivity problems in some scenarios where a system proxy configuration is present. In such scenarios, users might end up with no internet access, unless ProxyOptions has been configured with a final, null, fallback. Refer to ProxyOptions documentation.

@QuicOptions.Experimental
public CronetEngine.Builder setQuicOptions(QuicOptions quicOptions)

Configures the behavior of Cronet when using QUIC. For more details, see documentation of QuicOptions and the individual methods of QuicOptions.Builder.

Only relevant if enableQuic is enabled.

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.

public CronetEngine.Builder setThreadPriority(int priority)

Sets the thread priority of Cronet's internal thread.

public CronetEngine.Builder setUserAgent(String userAgent)

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