Package org.miaixz.bus.http.cache

Class DiskLruCache

java.lang.Object

org.miaixz.bus.http.cache.DiskLruCache

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public class DiskLruCache
extends Object
implements Closeable, Flushable

使用文件系统上有限空间的缓存。每个缓存条目都有一个字符串键和固定数量的值 每个键必须匹配regex [a-z0-9_-]{1,64}。值是字节序列，可以作为流或文件访问 每个值必须在0和Integer之间。MAX_VALUE字节的长度

Since:

Java 17+

Author:

Kimi Liu

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	DiskLruCache.DiskFile	Access to read and write files on a hierarchical data store.
final class	DiskLruCache.Editor	Edits the values for an entry.
final class	DiskLruCache.Snapshot	快照信息

Method Summary

Modifier and Type	Method	Description
void	close()	Closes this cache.
static DiskLruCache	create(DiskLruCache.DiskFile diskFile, File directory, int appVersion, int valueCount, long maxSize)	创建一个驻留在directory中的缓存。
void	delete()	Closes the cache and deletes all of its stored values.
DiskLruCache.Editor	edit(String key)	返回名为key的条目的编辑器，如果另一个编辑正在进行，则返回null
void	evictAll()	Deletes all stored values from the cache.
void	flush()	Force buffered operations to the filesystem.
DiskLruCache.Snapshot	get(String key)	返回名为key的条目的快照，如果条目不存在，则返回null， 否则当前无法读取。
File	getDirectory()	Returns the directory where this cache stores its data.
long	getMaxSize()	Returns the maximum number of bytes that this cache should use to store its data.
void	initialize()
boolean	isClosed()	Returns true if this cache has been closed.
boolean	remove(String key)	Drops the entry for key if it exists and can be removed.
void	setMaxSize(long maxSize)	Changes the maximum number of bytes the cache can store and queues a job to trim the existing store, if necessary.
long	size()	Returns the number of bytes currently being used to store the values in this cache.
Iterator<DiskLruCache.Snapshot>	snapshots()	返回缓存当前项的迭代器。

Methods inherited from class java.lang.Object

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

Method Details

create

public static DiskLruCache create(DiskLruCache.DiskFile diskFile,
 File directory,
 int appVersion,
 int valueCount,
 long maxSize)

创建一个驻留在directory中的缓存。此缓存在第一次访问时惰性初始化，如果它不存在，将创建它.

Parameters:

diskFile - 文件系统

directory - 一个可写目录

appVersion - 版本信息

valueCount - 每个缓存条目的值数目.

maxSize - 此缓存应用于存储的最大字节数

Returns:

the disk cache

initialize

public void initialize()
                throws IOException

Throws:

IOException

get

public DiskLruCache.Snapshot get(String key)
                          throws IOException

返回名为key的条目的快照，如果条目不存在，则返回null， 否则当前无法读取。如果返回一个值，它将被移动到LRU队列的头部

Parameters:

key - 缓存key

Returns:

the 快照信息

Throws:

IOException - 异常

edit

public DiskLruCache.Editor edit(String key)
                         throws IOException

返回名为key的条目的编辑器，如果另一个编辑正在进行，则返回null

Parameters:

key - 文件key

Returns:

编辑器

Throws:

IOException - 异常

getDirectory

public File getDirectory()

Returns the directory where this cache stores its data.

getMaxSize

public long getMaxSize()

Returns the maximum number of bytes that this cache should use to store its data.

setMaxSize

public void setMaxSize(long maxSize)

Changes the maximum number of bytes the cache can store and queues a job to trim the existing store, if necessary.

size

public long size()
          throws IOException

Returns the number of bytes currently being used to store the values in this cache. This may be greater than the max size if a background deletion is pending.

Throws:

IOException

remove

public boolean remove(String key)
               throws IOException

Drops the entry for key if it exists and can be removed. If the entry for key is currently being edited, that edit will complete normally but its value will not be stored.

Returns:

true if an entry was removed.

Throws:

IOException

isClosed

public boolean isClosed()

Returns true if this cache has been closed.

flush

public void flush()
           throws IOException

Force buffered operations to the filesystem.

Specified by:

flush in interface Flushable

Throws:

IOException

close

public void close()
           throws IOException

Closes this cache. Stored values will remain on the filesystem.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

delete

public void delete()
            throws IOException

Closes the cache and deletes all of its stored values. This will delete all files in the cache directory including files that weren't created by the cache.

Throws:

IOException

evictAll

public void evictAll()
              throws IOException

Deletes all stored values from the cache. In-flight edits will complete normally but their values will not be stored.

Throws:

IOException

snapshots

public Iterator<DiskLruCache.Snapshot> snapshots()
                                          throws IOException

返回缓存当前项的迭代器。这个迭代器不会抛出ConcurrentModificationException， 调用者必须DiskLruCache.Snapshot.close()每个由Iterator.next()返回的快照 如果做不到这一点，就会泄漏打开的文件,返回的迭代器支持 Iterator.remove().

Returns:

返回迭代器

Throws:

IOException - 异常