com.android.volley.toolbox

Class ImageLoader

java.lang.Object

com.android.volley.toolbox.ImageLoader

public class ImageLoader
extends Object

Helper that handles loading and caching images from remote URLs. The simple way to use this class is to call get(String, ImageListener) and to pass in the default image listener provided by getImageListener(ImageView, int, int). Note that all function calls to this class must be made from the main thead, and all responses will be delivered to the main thread as well.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ImageLoader.ImageCache Simple cache adapter interface.
class	ImageLoader.ImageContainer Container object for all of the data surrounding an image request.
static interface	ImageLoader.ImageListener Interface for the response handlers on image requests.

Constructor Summary

Constructors

Constructor and Description
ImageLoader(RequestQueue queue, ImageLoader.ImageCache imageCache) Constructs a new ImageLoader.

Method Summary

Methods

Modifier and Type	Method and Description
ImageLoader.ImageContainer	get(String requestUrl, ImageLoader.ImageListener listener) Returns an ImageContainer for the requested URL.
ImageLoader.ImageContainer	get(String requestUrl, ImageLoader.ImageListener imageListener, int maxWidth, int maxHeight, android.widget.ImageView.ScaleType scaleType) Issues a bitmap request with the given URL if that image is not available in the cache, and returns a bitmap container that contains all of the data relating to the request (as well as the default image if the requested image is not available).
static ImageLoader.ImageListener	getImageListener(android.widget.ImageView view, int defaultImageResId, int errorImageResId) The default implementation of ImageListener which handles basic functionality of showing a default image until the network response is received, at which point it will switch to either the actual image or the error image.
boolean	isCached(String requestUrl, int maxWidth, int maxHeight) Checks if the item is available in the cache.
protected Request<android.graphics.Bitmap>	makeImageRequest(String requestUrl, int maxWidth, int maxHeight, android.widget.ImageView.ScaleType scaleType, String cacheKey)
protected void	onGetImageError(String cacheKey, VolleyError error) Handler for when an image failed to load.
protected void	onGetImageSuccess(String cacheKey, android.graphics.Bitmap response) Handler for when an image was successfully loaded.
void	setBatchedResponseDelay(int newBatchedResponseDelayMs) Sets the amount of time to wait after the first response arrives before delivering all responses.

Methods inherited from class java.lang.Object

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

Constructor Detail

ImageLoader

public ImageLoader(RequestQueue queue,
           ImageLoader.ImageCache imageCache)

Constructs a new ImageLoader.

Parameters:

queue - The RequestQueue to use for making image requests.

imageCache - The cache to use as an L1 cache.

Method Detail

getImageListener

public static ImageLoader.ImageListener getImageListener(android.widget.ImageView view,
                                         int defaultImageResId,
                                         int errorImageResId)

The default implementation of ImageListener which handles basic functionality of showing a default image until the network response is received, at which point it will switch to either the actual image or the error image.

Parameters:

imageView - The imageView that the listener is associated with.

defaultImageResId - Default image resource ID to use, or 0 if it doesn't exist.

errorImageResId - Error image resource ID to use, or 0 if it doesn't exist.

isCached

public boolean isCached(String requestUrl,
               int maxWidth,
               int maxHeight)

Checks if the item is available in the cache.

Parameters:

requestUrl - The url of the remote image

maxWidth - The maximum width of the returned image.

maxHeight - The maximum height of the returned image.

Returns:

True if the item exists in cache, false otherwise.

get

public ImageLoader.ImageContainer get(String requestUrl,
                             ImageLoader.ImageListener listener)

Returns an ImageContainer for the requested URL. The ImageContainer will contain either the specified default bitmap or the loaded bitmap. If the default was returned, the ImageLoader will be invoked when the request is fulfilled.

Parameters:

requestUrl - The URL of the image to be loaded.

defaultImage - Optional default image to return until the actual image is loaded.

get

public ImageLoader.ImageContainer get(String requestUrl,
                             ImageLoader.ImageListener imageListener,
                             int maxWidth,
                             int maxHeight,
                             android.widget.ImageView.ScaleType scaleType)

Issues a bitmap request with the given URL if that image is not available in the cache, and returns a bitmap container that contains all of the data relating to the request (as well as the default image if the requested image is not available).

Parameters:

requestUrl - The url of the remote image

imageListener - The listener to call when the remote image is loaded

maxWidth - The maximum width of the returned image.

maxHeight - The maximum height of the returned image.

scaleType - The ImageViews ScaleType used to calculate the needed image size.

Returns:

A container object that contains all of the properties of the request, as well as the currently available image (default if remote is not loaded).

makeImageRequest

protected Request<android.graphics.Bitmap> makeImageRequest(String requestUrl,
                                                int maxWidth,
                                                int maxHeight,
                                                android.widget.ImageView.ScaleType scaleType,
                                                String cacheKey)

setBatchedResponseDelay

public void setBatchedResponseDelay(int newBatchedResponseDelayMs)

Sets the amount of time to wait after the first response arrives before delivering all responses. Batching can be disabled entirely by passing in 0.

Parameters:

newBatchedResponseDelayMs - The time in milliseconds to wait.

onGetImageSuccess

protected void onGetImageSuccess(String cacheKey,
                     android.graphics.Bitmap response)

Handler for when an image was successfully loaded.

Parameters:

cacheKey - The cache key that is associated with the image request.

response - The bitmap that was returned from the network.

onGetImageError

protected void onGetImageError(String cacheKey,
                   VolleyError error)

Handler for when an image failed to load.

Parameters:

cacheKey - The cache key that is associated with the image request.