Class HttpTransport

public abstract class HttpTransport

Thread-safe abstract HTTP transport.

Implementation is thread-safe, and sub-classes must be thread-safe. For maximum efficiency, applications should use a single globally-shared instance of the HTTP transport.

The recommended concrete implementation HTTP transport library to use depends on what environment you are running in:

  • Google App Engine: use com.google.api.client.extensions.appengine.http.UrlFetchTransport.
    • com.google.api.client.apache.ApacheHttpTransport doesn't work on App Engine because the Apache HTTP Client opens its own sockets (though in theory there are ways to hack it to work on App Engine that might work).
    • com.google.api.client.javanet.NetHttpTransport is discouraged due to a bug in the App Engine SDK itself in how it parses HTTP headers in the response.
  • Android:
    • For maximum backwards compatibility with older SDK's use newCompatibleTransport from com.google.api.client.extensions.android.http.AndroidHttp (read its JavaDoc for details).
    • If your application is targeting Gingerbread (SDK 2.3) or higher, simply use com.google.api.client.javanet.NetHttpTransport.
  • Other Java environments
    • com.google.api.client.googleapis.javanet.GoogleNetHttpTransport is included in google-api-cient 1.22.0, so easy to include.
    • com.google.api.client.javanet.NetHttpTransport is based on the HttpURLConnection built into the Java SDK, so it used to be the preferred choice.
    • com.google.api.client.apache.ApacheHttpTransport is a good choice for users of the Apache HTTP Client, especially if you need some of the configuration options available in that library.
  • Some HTTP transports do not support all HTTP methods. Use #supportsMethod(String) to check if a certain HTTP method is supported. Calling #buildRequest() on a method that is not supported will result in an IllegalArgumentException.

    Subclasses should override #supportsMethod(String) and #buildRequest(String, String) to build requests and specify which HTTP methods are supported.

    Inheritance

    java.lang.Object > HttpTransport

    Constructors

    HttpTransport()

    public HttpTransport()

    Methods

    buildRequest(String method, String url)

    protected abstract LowLevelHttpRequest buildRequest(String method, String url)

    Builds a low level HTTP request for the given HTTP method.

    Parameters
    NameDescription
    methodString

    HTTP method

    urlString

    URL

    Returns
    TypeDescription
    LowLevelHttpRequest

    new low level HTTP request

    Exceptions
    TypeDescription
    IOException

    if HTTP method is not supported

    createRequestFactory()

    public final HttpRequestFactory createRequestFactory()

    Returns a new instance of an HTTP request factory based on this HTTP transport.

    Returns
    TypeDescription
    HttpRequestFactory

    new instance of an HTTP request factory

    createRequestFactory(HttpRequestInitializer initializer)

    public final HttpRequestFactory createRequestFactory(HttpRequestInitializer initializer)

    Returns a new instance of an HTTP request factory based on this HTTP transport with the given HTTP request initializer.

    Parameter
    NameDescription
    initializerHttpRequestInitializer

    HTTP request initializer or null for none

    Returns
    TypeDescription
    HttpRequestFactory

    new instance of an HTTP request factory

    isMtls()

    public boolean isMtls()

    Returns whether the transport is mTLS.

    Returns
    TypeDescription
    boolean

    boolean indicating if the transport is mTLS.

    shutdown()

    public void shutdown()

    Default implementation does nothing, but subclasses may override to possibly release allocated system resources or close connections.

    Exceptions
    TypeDescription
    IOException

    I/O exception

    supportsMethod(String method)

    public boolean supportsMethod(String method)

    Returns whether a specified HTTP method is supported by this transport.

    Default implementation returns true if and only if the request method is "DELETE", "GET", "POST", or "PUT". Subclasses should override.

    Parameter
    NameDescription
    methodString

    HTTP method

    Returns
    TypeDescription
    boolean
    Exceptions
    TypeDescription
    IOException

    I/O exception