# Class CachedDataService

java.lang.Object
com.codename1.io.ConnectionRequest
com.codename1.io.services.CachedDataService

All Implemented Interfaces:
  `IOProgressListener`

public final class CachedDataService extends ConnectionRequest
Simple service that allows downloading and caching data locally. When the data is requested again the server is queried with a conditional get query.

- ## Nested Class Summary

  ### Nested classes/interfaces inherited from class ConnectionRequest

  `ConnectionRequest.CachingMode, ConnectionRequest.SSLCertificate`

- ## Field Summary

  ### Fields inherited from class ConnectionRequest

  `PRIORITY_CRITICAL, PRIORITY_HIGH, PRIORITY_LOW, PRIORITY_NORMAL, PRIORITY_REDUNDANT`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `equals(Object o)`
  Indicates whether some other object is "equal to" this one.
  `protected void`
  `handleErrorResponseCode(int code, String message)`
  Handles a server response code that is not 200 and not a redirect (unless redirect handling is disabled)
  `protected void`
  `handleException(Exception err)`
  Handles an exception thrown when performing a network operation, the default implementation shows a retry dialog.
  `int`
  `hashCode()`
  Returns a hash code value for the object.
  `protected void`
  `readHeaders(Object connection)`
  Allows reading the headers from the connection by calling the getHeader() method.
  `protected void`
  `readResponse(InputStream input)`
  Callback for the server response with the input stream from the server.
  `static void`
  `register()`
  Makes sure the cached data class is properly registered as an externalizable.
  `static void`
  `updateData(CachedData d, ActionListener callback)`
  Checks that the cached data is up to date and if a newer version exits it updates the data in place

  ### Methods inherited from class ConnectionRequest

  `addArgument, addArgument, addArgument, addArgumentArray, addArgumentNoEncoding, addArgumentNoEncoding, addArgumentNoEncodingArray, addArguments, addExceptionListener, addRequestHeader, addResponseCodeListener, addResponseListener, buildRequestBody, cacheUnmodified, canGetSSLCertificates, checkSSLCertificates, cookieReceived, cookieSent, createRequestURL, downloadImageToFileSystem, downloadImageToFileSystem, downloadImageToFileSystem, downloadImageToFileSystem, downloadImageToFileSystem, downloadImageToFileSystem, downloadImageToStorage, downloadImageToStorage, downloadImageToStorage, downloadImageToStorage, downloadImageToStorage, downloadImageToStorage, fetchJSON, fetchJSONAsync, fireResponseListener, getCachedData, getCacheMode, getContentLength, getContentType, getCookieHeader, getDefaultCacheMode, getDefaultUserAgent, getDestinationFile, getDestinationStorage, getDisposeOnCompletion, getHeader, getHeaderFieldNames, getHeaders, getHttpMethod, getPriority, getReadTimeout, getRequestBody, getRequestBodyData, getResponseCode, getResponseContentType, getResponseData, getResponseErrorMessage, getResposeCode, getShowOnInit, getSilentRetryCount, getSSLCertificates, getTimeout, getUrl, getUserAgent, getYield, handleIOException, handleRuntimeException, hasResponseListeners, initConnection, initCookieHeader, ioStreamUpdate, isCheckSSLCertificates, isCookiesEnabled, isCookiesEnabledDefault, isDefaultFollowRedirects, isDuplicateSupported, isFailSilently, isFollowRedirects, isHandleErrorCodesInGlobalErrorHandler, isInsecure, isKilled, isNativeCookieSharingSupported, isPausable, isPaused, isPost, isReadRequest, isReadResponseForErrors, isReadResponseForErrorsDefault, isReadTimeoutSupported, isRedirecting, isWriteRequest, kill, onRedirect, pause, postResponse, purgeCache, purgeCacheDirectory, readErrorCodeHeaders, removeAllArguments, removeArgument, removeExceptionListener, removeRequestHeader, removeRequestHeaderIfUnchanged, removeResponseCodeListener, removeResponseListener, resume, retry, setCacheMode, setCheckSSLCertificates, setChunkedStreamingMode, setContentType, setCookieHeader, setCookiesEnabled, setCookiesEnabledDefault, setDefaultCacheMode, setDefaultFollowRedirects, setDefaultUserAgent, setDestinationFile, setDestinationStorage, setDisposeOnCompletion, setDuplicateSupported, setFailSilently, setFollowRedirects, setHandleErrorCodesInGlobalErrorHandler, setHttpMethod, setInsecure, setKilled, setPaused, setPost, setPriority, setReadRequest, setReadResponseForErrors, setReadResponseForErrorsDefault, setReadTimeout, setRequestBody, setRequestBody, setShowOnInit, setSilentRetryCount, setTimeout, setUrl, setUseNativeCookieStore, setUserAgent, setWriteRequest, shouldAutoCloseResponse, shouldConvertPostToGetOnRedirect, shouldStop, shouldWriteUTFAsGetBytes, validate`

  ### Methods inherited from class Object

  `clone, getClass, notify, notifyAll, toString, wait, wait, wait`

- ## Method Details

  - ### register

    public static void register()
    Makes sure the cached data class is properly registered as an externalizable. This must be invoked for caching to work

  - ### updateData

    public static void updateData(CachedData d, ActionListener callback)

    Checks that the cached data is up to date and if a newer version exits it updates the data in place

    ###### Parameters

    - `d`: the data to check

    - `callback`: optional callback to be invoked on request completion

  - ### equals

    public boolean equals(Object o)
    Description copied from class: `ConnectionRequest`
    Indicates whether some other object is "equal to" this one. The equals method implements an equivalence relation: It is reflexive: for any reference value x, x.equals(x) should return true. It is symmetric: for any reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true. It is transitive: for any reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true. It is consistent: for any reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the object is modified. For any non-null reference value x, x.equals(null) should return false. The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any reference values x and y, this method returns true if and only if x and y refer to the same object (x==y has the value true).
    Overrides:
      `equals` in class `ConnectionRequest`

  - ### hashCode

    public int hashCode()
    Description copied from class: `ConnectionRequest`
    Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable. The general contract of hashCode is: Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result. It is not required that if two objects are unequal according to the equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables. As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
    Overrides:
      `hashCode` in class `ConnectionRequest`

  - ### handleException

    protected void handleException(Exception err)

    Handles an exception thrown when performing a network operation, the default implementation shows a retry dialog.

    ###### Parameters

    - `err`: the exception thrown
    Overrides:
      `handleException` in class `ConnectionRequest`

  - ### handleErrorResponseCode

    protected void handleErrorResponseCode(int code, String message)

    Handles a server response code that is not 200 and not a redirect (unless redirect handling is disabled)

    ###### Parameters

    - `code`: the response code from the server

    - `message`: the response message from the server

    Overrides:
      `handleErrorResponseCode` in class `ConnectionRequest`

  - ### readHeaders

    protected void readHeaders(Object connection) throws IOException

    Allows reading the headers from the connection by calling the getHeader() method.

    ###### Parameters

    - `connection`: used when invoking getHeader

    ###### Throws

    - `java.io.IOException`: thrown on failure
    Overrides:
      `readHeaders` in class `ConnectionRequest`
    Throws:
      `IOException`

  - ### readResponse

    protected void readResponse(InputStream input) throws IOException

    Callback for the server response with the input stream from the server. This method is invoked on the network thread

    ###### Parameters

    - `input`: the input stream containing the response

    ###### Throws

    - `IOException`: when a read input occurs
    Overrides:
      `readResponse` in class `ConnectionRequest`
    Throws:
      `IOException`