public final class Cache
extends java.lang.Object
GET
. The server will then send either the updated response if it has
changed, or a short 'not modified' response if the client's copy is still
valid. Such responses increment both the network count and hit count.
The best way to improve the cache hit rate is by configuring the web server to return cacheable responses. Although this client honors all HTTP/1.1 (RFC 2068) cache headers, it doesn't cache partial responses.
no-cache
directive: connection.addRequestProperty("Cache-Control", "no-cache");
If it is only necessary to force a cached response to be validated by the
server, use the more efficient max-age=0
instead: connection.addRequestProperty("Cache-Control", "max-age=0");
only-if-cached
directive: try {
connection.addRequestProperty("Cache-Control", "only-if-cached");
InputStream cached = connection.getInputStream();
// the resource was cached! show it
} catch (FileNotFoundException e) {
// the resource was not cached
}
This technique works even better in situations where a stale response is
better than no response. To permit stale cached responses, use the max-stale
directive with the maximum staleness in seconds: int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
connection.addRequestProperty("Cache-Control", "max-stale=" + maxStale);
Constructor and Description |
---|
Cache(java.io.File directory,
long maxSize) |
Modifier and Type | Method and Description |
---|---|
void |
close() |
void |
delete()
Closes the cache and deletes all of its stored values.
|
void |
evictAll()
Deletes all values stored in the cache.
|
void |
flush() |
java.io.File |
getDirectory() |
int |
getHitCount() |
long |
getMaxSize() |
int |
getNetworkCount() |
int |
getRequestCount() |
long |
getSize() |
int |
getWriteAbortCount() |
int |
getWriteSuccessCount() |
boolean |
isClosed() |
public Cache(java.io.File directory, long maxSize) throws java.io.IOException
java.io.IOException
public void delete() throws java.io.IOException
java.io.IOException
public void evictAll() throws java.io.IOException
java.io.IOException
public int getWriteAbortCount()
public int getWriteSuccessCount()
public long getSize()
public long getMaxSize()
public void flush() throws java.io.IOException
java.io.IOException
public void close() throws java.io.IOException
java.io.IOException
public java.io.File getDirectory()
public boolean isClosed()
public int getNetworkCount()
public int getHitCount()
public int getRequestCount()
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