uk.co.sevendigital.android.sdk.util

Class VolleyUtil.CacheEntryRequest<T>

java.lang.Object

com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

uk.co.sevendigital.android.sdk.util.VolleyUtil.CacheEntryRequest<T>

Type Parameters:

T - The type of the response returned from the server.

All Implemented Interfaces:

java.lang.Comparable<com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>>

Direct Known Subclasses:

VolleyUtil.StringRequest

Enclosing class:

VolleyUtil

public abstract static class VolleyUtil.CacheEntryRequest<T>
extends com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

The VolleyUtil.CacheEntryRequest class is an extension of Volley's Request class and is used to return a response that contains both the information returned from the server and the cache entry associated with the returned response.

The cache entry is used by Volley to determine if a previously retrieved response (cached on the disk) can be returned immediately without contacting the server. The cache entry ttl (time to live) is determined by the header values on the returned response. The time to live value of response (stored within the cache entry) can be used determine if a returned network response requires action or if it can be ignored because the request has been processed before.

For example: If a network request is to be made to update entries stored in the database, the request can be sent to Volley for processing. If the ttl (time to live) of the returned cache entry matches the ttl value at which the database was most recently updated, the update can be ignored.

By default, Volley reconstructs the cache entry from the cached network response when a response is returned from disk. This results in a different ttl value (in the cache entry) than previously returned (for the same response). This class works around that limitation and returns a cache entry with identical ttl.

Note: Volley only uses the "expires" and "max-age" headers in the response to decide on how long a piece of content should be cached. To implement a custom caching mechanism, override the parseCacheHeaders(com.android.volley.NetworkResponse) method and set custom values for the ttl (time to live) and soft ttl (soft time to live - the point at which content should be prefetched).

Note: The returned VolleyUtil.CacheEntryResponse is not guaranteed to have a non-null cache entry. If the request should not explicitly cache the result, the returned cache entry will be null (indicating the result was not cached).

Nested Class Summary

Nested classes/interfaces inherited from class com.android.volley.Request

com.android.volley.Request.Method, com.android.volley.Request.Priority

Constructor Summary

Constructors

Constructor and Description
CacheEntryRequest(VolleyUtil.CacheEntryRequestParams params, com.android.volley.Response.Listener<VolleyUtil.CacheEntryResponse<T>> listener, com.android.volley.Response.ErrorListener errorListener)

Method Summary

Modifier and Type	Method and Description
protected void	deliverResponse(VolleyUtil.CacheEntryResponse<T> response) Subclasses must implement this to perform delivery of the parsed response to their listeners.
byte[]	getBody() Returns the raw POST or PUT body to be sent.
java.lang.String	getBodyContentType()
java.lang.String	getCacheKey() Returns the cache key for this request.
java.util.Map<java.lang.String,java.lang.String>	getHeaders() Returns a list of extra HTTP headers to go along with this request.
protected java.util.Map<java.lang.String,java.lang.String>	getParams() Returns a Map of parameters to be used for a POST or PUT request.
VolleyUtil.CacheEntryRequestParams	getRequestParams()
protected com.android.volley.Cache.Entry	parseCacheHeaders(com.android.volley.NetworkResponse nr)
protected com.android.volley.Response<VolleyUtil.CacheEntryResponse<T>>	parseNetworkResponse(com.android.volley.NetworkResponse nr) Subclasses must implement this to parse the raw network response and return an appropriate response type.
protected VolleyUtil.CacheEntryResponse<T>	parseNetworkResponseCacheEntry(com.android.volley.NetworkResponse nr)
protected abstract T	parseNetworkResponseObject(com.android.volley.NetworkResponse nr)

Methods inherited from class com.android.volley.Request

addMarker, cancel, compareTo, deliverError, getCacheEntry, getMethod, getParamsEncoding, getPostBody, getPostBodyContentType, getPostParams, getPostParamsEncoding, getPriority, getRetryPolicy, getSequence, getTag, getTimeoutMs, getTrafficStatsTag, getUrl, hasHadResponseDelivered, isCanceled, markDelivered, parseNetworkError, setCacheEntry, setRequestQueue, setRetryPolicy, setSequence, setShouldCache, setTag, shouldCache, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

CacheEntryRequest

public CacheEntryRequest(VolleyUtil.CacheEntryRequestParams params,
                         com.android.volley.Response.Listener<VolleyUtil.CacheEntryResponse<T>> listener,
                         com.android.volley.Response.ErrorListener errorListener)

Method Detail

getRequestParams

public VolleyUtil.CacheEntryRequestParams getRequestParams()

getCacheKey

public java.lang.String getCacheKey()

Description copied from class: com.android.volley.Request

Returns the cache key for this request. By default, this is the URL.

Overrides:

getCacheKey in class com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

getHeaders

public java.util.Map<java.lang.String,java.lang.String> getHeaders()
                                                            throws com.android.volley.AuthFailureError

Description copied from class: com.android.volley.Request

Returns a list of extra HTTP headers to go along with this request. Can throw AuthFailureError as authentication may be required to provide these values.

Overrides:

getHeaders in class com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

Throws:

com.android.volley.AuthFailureError - In the event of auth failure

getParams

protected java.util.Map<java.lang.String,java.lang.String> getParams()
                                                              throws com.android.volley.AuthFailureError

Description copied from class: com.android.volley.Request

Returns a Map of parameters to be used for a POST or PUT request. Can throw AuthFailureError as authentication may be required to provide these values.

Note that you can directly override Request.getBody() for custom data.

Overrides:

getParams in class com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

Throws:

com.android.volley.AuthFailureError - in the event of auth failure

getBodyContentType

public java.lang.String getBodyContentType()

Overrides:

getBodyContentType in class com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

getBody

public byte[] getBody()
               throws com.android.volley.AuthFailureError

Description copied from class: com.android.volley.Request

Returns the raw POST or PUT body to be sent.

Overrides:

getBody in class com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

Throws:

com.android.volley.AuthFailureError - in the event of auth failure

parseNetworkResponse

protected final com.android.volley.Response<VolleyUtil.CacheEntryResponse<T>> parseNetworkResponse(com.android.volley.NetworkResponse nr)

Description copied from class: com.android.volley.Request

Subclasses must implement this to parse the raw network response and return an appropriate response type. This method will be called from a worker thread. The response will not be delivered if you return null.

Specified by:

parseNetworkResponse in class com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

Parameters:

nr - Response from the network

Returns:

The parsed response, or null in the case of an error

parseNetworkResponseCacheEntry

protected final VolleyUtil.CacheEntryResponse<T> parseNetworkResponseCacheEntry(com.android.volley.NetworkResponse nr)
                                                                         throws com.android.volley.VolleyError

Throws:

com.android.volley.VolleyError

parseNetworkResponseObject

protected abstract T parseNetworkResponseObject(com.android.volley.NetworkResponse nr)
                                         throws com.android.volley.VolleyError

Throws:

com.android.volley.VolleyError

parseCacheHeaders

protected com.android.volley.Cache.Entry parseCacheHeaders(com.android.volley.NetworkResponse nr)

deliverResponse

protected void deliverResponse(VolleyUtil.CacheEntryResponse<T> response)

Description copied from class: com.android.volley.Request

Subclasses must implement this to perform delivery of the parsed response to their listeners. The given response is guaranteed to be non-null; responses that fail to parse are not delivered.

Specified by:

deliverResponse in class com.android.volley.Request<VolleyUtil.CacheEntryResponse<T>>

Parameters:

response - The parsed response returned by Request.parseNetworkResponse(NetworkResponse)