uk.co.senab.bitmapcache

Class BitmapLruCache

java.lang.Object

uk.co.senab.bitmapcache.BitmapLruCache

public class BitmapLruCache
extends Object

A cache which can be set to use multiple layers of caching for Bitmap objects in an Android app. Instances are created via a BitmapLruCache.Builder instance, which can be used to alter the settings of the resulting cache.

Instances of this class should ideally be kept globally with the application, for example in the Application object. You should also use the bundled CacheableImageView wherever possible, as the memory cache has a closeStream relationship with it.

Clients can call get(String) to retrieve a cached value from the given Url. This will check all available caches for the value. There are also the getFromDiskCache(String, android.graphics.BitmapFactory.Options) and getFromMemoryCache(String) which allow more granular access.

There are a number of update methods. put(String, InputStream) and put(String, InputStream) are the preferred versions of the method, as they allow 1:1 caching to disk of the original content.
put(String, Bitmap)} should only be used if you can't get access to the original InputStream.

Author:

Chris Banes

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BitmapLruCache.Builder Builder class for {link BitmapLruCache.
static class	BitmapLruCache.RecyclePolicy The recycle policy controls if the Bitmap.recycle() is automatically called, when it is no longer being used.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	contains(String url) Returns whether any of the enabled caches contain the specified URL.
boolean	containsInDiskCache(String url) Returns whether the Disk Cache contains the specified URL.
boolean	containsInMemoryCache(String url) Returns whether the Memory Cache contains the specified URL.
CacheableBitmapDrawable	get(String url) Returns the value for url.
CacheableBitmapDrawable	get(String url, android.graphics.BitmapFactory.Options decodeOpts) Returns the value for url.
CacheableBitmapDrawable	getFromDiskCache(String url, android.graphics.BitmapFactory.Options decodeOpts) Returns the value for url in the disk cache only.
CacheableBitmapDrawable	getFromMemoryCache(String url) Returns the value for url in the memory cache only.
boolean	isDiskCacheEnabled()
boolean	isMemoryCacheEnabled()
CacheableBitmapDrawable	put(String url, android.graphics.Bitmap bitmap) Caches bitmap for url into all enabled caches.
CacheableBitmapDrawable	put(String url, android.graphics.Bitmap bitmap, android.graphics.Bitmap.CompressFormat compressFormat, int compressQuality) Caches bitmap for url into all enabled caches.
CacheableBitmapDrawable	put(String url, InputStream inputStream) Caches resulting bitmap from inputStream for url into all enabled caches.
CacheableBitmapDrawable	put(String url, InputStream inputStream, android.graphics.BitmapFactory.Options decodeOpts) Caches resulting bitmap from inputStream for url into all enabled caches.
void	remove(String url) Removes the entry for url from all enabled caches, if it exists.
void	trimMemory() This method iterates through the memory cache (if enabled) and removes any entries which are not currently being displayed.

Methods inherited from class java.lang.Object

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

Method Detail

contains

public boolean contains(String url)

Returns whether any of the enabled caches contain the specified URL.

If you have the disk cache enabled, you should not call this method from main/UI thread.

Parameters:

url - the URL to search for.

Returns:

true if any of the caches contain the specified URL, false otherwise.

containsInDiskCache

public boolean containsInDiskCache(String url)

Returns whether the Disk Cache contains the specified URL. You should not call this method from main/UI thread.

Parameters:

url - the URL to search for.

Returns:

true if the Disk Cache is enabled and contains the specified URL, false otherwise.

containsInMemoryCache

public boolean containsInMemoryCache(String url)

Returns whether the Memory Cache contains the specified URL. This method is safe to be called from the main thread.

Parameters:

url - the URL to search for.

Returns:

true if the Memory Cache is enabled and contains the specified URL, false otherwise.

get

public CacheableBitmapDrawable get(String url)

Returns the value for url. This will check all caches currently enabled.

If you have the disk cache enabled, you should not call this method from main/UI thread.

Parameters:

url - - String representing the URL of the image

get

public CacheableBitmapDrawable get(String url,
                          android.graphics.BitmapFactory.Options decodeOpts)

Returns the value for url. This will check all caches currently enabled.

If you have the disk cache enabled, you should not call this method from main/UI thread.

Parameters:

url - - String representing the URL of the image

decodeOpts - - Options used for decoding the contents from the disk cache only.

getFromDiskCache

public CacheableBitmapDrawable getFromDiskCache(String url,
                                       android.graphics.BitmapFactory.Options decodeOpts)

Returns the value for url in the disk cache only. You should not call this method from main/UI thread.

If enabled, the result of this method will be cached in the memory cache.

Unless you have a specific requirement to only query the disk cache, you should call get(String) instead.

Parameters:

url - - String representing the URL of the image

decodeOpts - - Options used for decoding the contents from the disk cache.

Returns:

Value for url from disk cache, or null if the disk cache is not enabled.

getFromMemoryCache

public CacheableBitmapDrawable getFromMemoryCache(String url)

Returns the value for url in the memory cache only. This method is safe to be called from the main thread.

You should check the result of this method before starting a threaded call.

Parameters:

url - - String representing the URL of the image

Returns:

Value for url from memory cache, or null if the disk cache is not enabled.

isDiskCacheEnabled

public boolean isDiskCacheEnabled()

Returns:

true if the Disk Cache is enabled.

isMemoryCacheEnabled

public boolean isMemoryCacheEnabled()

Returns:

true if the Memory Cache is enabled.

put

public CacheableBitmapDrawable put(String url,
                          android.graphics.Bitmap bitmap)

Caches bitmap for url into all enabled caches. If the disk cache is enabled, the bitmap will be compressed losslessly.

If you have the disk cache enabled, you should not call this method from main/UI thread.

Parameters:

url - - String representing the URL of the image.

bitmap - - Bitmap which has been decoded from url.

Returns:

CacheableBitmapDrawable which can be used to display the bitmap.

put

public CacheableBitmapDrawable put(String url,
                          android.graphics.Bitmap bitmap,
                          android.graphics.Bitmap.CompressFormat compressFormat,
                          int compressQuality)

Caches bitmap for url into all enabled caches. If the disk cache is enabled, the bitmap will be compressed with the settings you provide.

If you have the disk cache enabled, you should not call this method from main/UI thread.

Parameters:

url - - String representing the URL of the image.

bitmap - - Bitmap which has been decoded from url.

compressFormat - - Compression Format to use

compressQuality - - Level of compression to use

Returns:

CacheableBitmapDrawable which can be used to display the bitmap.

See Also:

Bitmap.compress(Bitmap.CompressFormat, int, OutputStream)

put

public CacheableBitmapDrawable put(String url,
                          InputStream inputStream)

Caches resulting bitmap from inputStream for url into all enabled caches. This version of the method should be preferred as it allows the original image contents to be cached, rather than a re-compressed version.

The contents of the InputStream will be copied to a temporary file, then the file will be decoded into a Bitmap. Providing the decode worked:

• If the memory cache is enabled, the decoded Bitmap will be cached to memory.
• If the disk cache is enabled, the contents of the original stream will be cached to disk.

You should not call this method from the main/UI thread.

Parameters:

url - - String representing the URL of the image

inputStream - - InputStream opened from url

Returns:

CacheableBitmapDrawable which can be used to display the bitmap.

put

public CacheableBitmapDrawable put(String url,
                          InputStream inputStream,
                          android.graphics.BitmapFactory.Options decodeOpts)

Caches resulting bitmap from inputStream for url into all enabled caches. This version of the method should be preferred as it allows the original image contents to be cached, rather than a re-compressed version.

The contents of the InputStream will be copied to a temporary file, then the file will be decoded into a Bitmap, using the optional decodeOpts. Providing the decode worked:

• If the memory cache is enabled, the decoded Bitmap will be cached to memory.
• If the disk cache is enabled, the contents of the original stream will be cached to disk.

You should not call this method from the main/UI thread.

Parameters:

url - - String representing the URL of the image

inputStream - - InputStream opened from url

decodeOpts - - Options used for decoding. This does not affect what is cached in the disk cache (if enabled).

Returns:

CacheableBitmapDrawable which can be used to display the bitmap.

remove

public void remove(String url)

Removes the entry for url from all enabled caches, if it exists.

If you have the disk cache enabled, you should not call this method from main/UI thread.

trimMemory

public void trimMemory()

This method iterates through the memory cache (if enabled) and removes any entries which are not currently being displayed. A good place to call this would be from Application.onLowMemory().