The com.danga.MemCached
class within Java
provides a native interface to memcached
instances. You can obtain the client from
http://whalin.com/memcached/. The Java class uses
hashes that are compatible with libmemcached
,
so you can mix and match Java and
libmemcached
applications accessing the same
memcached instances. The serialization
between Java and other interfaces will not be compatible. If
this is a problem, use JSON or a similar nonbinary serialization
format.
On most systems you can download the package and use the
jar
directly. On OpenSolaris, use
pkg to install the
SUNWmemcached-java
package.
To use the com.danga.MemCached
interface, you
create a MemCachedClient
instance and then
configure the list of servers by configuring the
SockIOPool
. Through the pool specification
you set up the server list, weighting, and the connection
parameters to optimized the connections between your client and
the memcached instances that you configure.
Generally you can configure the memcached interface once within a single class and then use this interface throughout the rest of your application.
For example, to create a basic interface, first configure the
MemCachedClient
and base
SockIOPool
settings:
public class MyClass { protected static MemCachedClient mcc = new MemCachedClient(); static { String[] servers = { "localhost:11211", }; Integer[] weights = { 1 }; SockIOPool pool = SockIOPool.getInstance(); pool.setServers( servers ); pool.setWeights( weights );
In the above sample, the list of servers is configured by creating an array of the memcached instances that you want to use. You can then configure individual weights for each server.
The remainder of the properties for the connection are optional, but you can set the connection numbers (initial connections, minimum connections, maximum connections, and the idle timeout) by setting the pool parameters:
pool.setInitConn( 5 ); pool.setMinConn( 5 ); pool.setMaxConn( 250 ); pool.setMaxIdle( 1000 * 60 * 60 * 6
Once the parameters have been configured, initialize the connection pool:
pool.initialize();
The pool, and the connection to your memcached instances should now be ready to use.
To set the hashing algorithm used to select the server used when
storing a given key you can use
pool.setHashingAlg()
:
pool.setHashingAlg( SockIOPool.NEW_COMPAT_HASH );
Valid values ares NEW_COMPAT_HASH
,
OLD_COMPAT_HASH
and
NATIVE_HASH
are also basic modula hashing
algorithms. For a consistent hashing algorithm, use
CONSISTENT_HASH
. These constants are
equivalent to the corresponding hash settings within
libmemcached
.
Java com.danga.MemCached Method |
Equivalent to |
---|---|
get() |
Generic get()
|
getMulti(keys) |
Get the values of multiple keys , returning the
information as Hash map using
java.lang.String for the keys and
java.lang.Object for the
corresponding values. |
set() |
Generic set()
|
add() |
Generic add()
|
replace() |
Generic replace()
|
delete() |
Generic delete()
|
incr() |
Generic incr()
|
decr() |
Generic decr()
|
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