Memcached使用总结

浏览数：59 / 时间：2015年06月20日

memcached作为高速运行的分布式缓存服务器，具有以下的特点。

  •  协议简单
  • 基于libevent的事件处理
  • · 内置内存存储方式
  • · memcached不互相通信的分布式

 存储方式 

为了提高性能, memcached中保存的数据都存储在memcached内置的内存存储空间中。由于数据仅存在于内存中，因此重启memcached、重启操作系统会导致全部数据消失。

此外，内容容量达到指定值之后，就基于LRU(Least Recently Used)算法自动删除不使用的缓存。

memcached本身是为缓存而设计的服务器，因此并没有过多考虑数据的永久性问题。

通信分布式

memcached尽管是“分布式”缓存服务器，但服务器端并没有分布式功能。各个memcached不会互相通信以共享信息。那么，怎样进行分布式呢？这完全取决于客户端的实现。

Memcached Client简要介绍 
Memcached Client目前有3种： 

这三种Client一直存在各种争议： 
  • Memcached Client for Java 比 SpyMemcached更稳定、更早、更广泛；
  • SpyMemcached 比 Memcached Client for Java更高效；
  • XMemcached 比 SpyMemcache并发效果更好。
XMemcached特性 
XMemcached特性： 
  • 高性能
  • 支持完整的memcached文本协议,二进制协议。
  • 支持JMX，可以通过MBean调整性能参数、动态添加/移除server、查看统计等。
  • 支持客户端统计
  • 支持memcached节点的动态增减。
  • 支持memcached分布:余数分布和一致性哈希分布。
  • 更多的性能调整选项。
（此外，XMemcached更容易与Spring集成。而且，属于中国原创！）


XMemcached简单实现 

MemcachedClientBuilder是MemcachedClient核心接口，用来控制Client的构建（build()方法）和关闭（shutdown()方法）。 
XMemcachedClientBuilder一般通过构造方法配置地址列表，通常还要配置权重，代码如下： 

<span style="font-size: 14px;">	</span><span style="font-size:14px;">public XMemcachedClientBuilder(List<InetSocketAddress> addressList) {
		if (addressList != null) {
			for (InetSocketAddress addr : addressList) {
				this.addressMap.put(addr, null);
			}
		}
	}

	public XMemcachedClientBuilder(List<InetSocketAddress> addressList,
			int[] weights) {
		if (addressList != null) {
			for (InetSocketAddress addr : addressList) {
				this.addressMap.put(addr, null);
			}
		}
		this.weights = weights;
	}</span>

此外，还需要设置连接池大小，使用二进制协议/文本协议等。 
通过build()方法获得MemcachedClient 
然后就可以通过Memcached进行set、get、replace、delete等Memcached操作了！

<span style="font-size:14px;">import static junit.framework.Assert.*;

import java.io.IOException;
import java.util.concurrent.TimeoutException;

import net.rubyeye.xmemcached.MemcachedClient;
import net.rubyeye.xmemcached.MemcachedClientBuilder;
import net.rubyeye.xmemcached.XMemcachedClientBuilder;
import net.rubyeye.xmemcached.command.BinaryCommandFactory;
import net.rubyeye.xmemcached.exception.MemcachedException;
import net.rubyeye.xmemcached.utils.AddrUtil;

import org.junit.Test;

public class MemcachedClientTest {
	@Test
	public void test() {
		MemcachedClientBuilder builder = new XMemcachedClientBuilder(
				AddrUtil.getAddresses("10.11.155.26:11211 10.11.155.41:11211 10.10.76.31:11211 10.10.76.35:11211"),
				new int[] { 1, 1, 1, 1 });
		
		// 设置连接池大小，即客户端个数
		builder.setConnectionPoolSize(50);

		// 宕机报警
		builder.setFailureMode(true);

		// 使用二进制文件
		builder.setCommandFactory(new BinaryCommandFactory());

		MemcachedClient memcachedClient = null;
		try {
			memcachedClient = builder.build();
			try {
				// 设置/获取
				memcachedClient.set("zlex", 36000, "set/get");
				assertEquals("set/get", memcachedClient.get("zlex"));

				// 替换
				memcachedClient.replace("zlex", 36000, "replace");
				assertEquals("replace", memcachedClient.get("zlex"));

				// 移除
				memcachedClient.delete("zlex");
				assertNull(memcachedClient.get("zlex"));
			} catch (TimeoutException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (MemcachedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			if (memcachedClient != null) {
				try {
					memcachedClient.shutdown();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	}
}</span><span style="font-size: 14px;">
</span>

XMemcached与Spring集成 

XMemcached与Spring集成可以参考http://code.google.com/p/xmemcached/wiki/Spring_Integration，这里只说最常用的方法。 
memcached.properties做基本配置： 

Properties代码：

#连接池大小即客户端个数
memcached.connectionPoolSize=50
memcached.failureMode=true
#server1
memcached.server1.host=10.11.155.26
memcached.server1.port=11211
memcached.server1.weight=4
#server2
memcached.server2.host=10.11.155.41
memcached.server2.port=11211
memcached.server2.weight=3				
#server3
memcached.server3.host=10.10.76.31
memcached.server3.port=11211
memcached.server3.weight=2					
#server4
memcached.server4.host=10.10.76.35
memcached.server4.port=11211
memcached.server4.weight=1


xml配置文件：
<?xml version="1.0" encoding="UTF-8"?>
<beans
	xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
	<!-- http://code.google.com/p/xmemcached/wiki/Spring_Integration -->
	<context:property-placeholder location="memcached.properties" />
	<bean
		id="memcachedClientBuilder"
		class="net.rubyeye.xmemcached.XMemcachedClientBuilder"
		p:connectionPoolSize="${memcached.connectionPoolSize}"
		p:failureMode="${memcached.failureMode}">
		<!-- XMemcachedClientBuilder have two arguments.First is server list,and 
			second is weights array. -->
		<constructor-arg>
			<list>
				<bean class="java.net.InetSocketAddress">
					<constructor-arg>
						<value>${memcached.server1.host}</value>
					</constructor-arg>
					<constructor-arg>
						<value>${memcached.server1.port}</value>
					</constructor-arg>
				</bean>
				<bean class="java.net.InetSocketAddress">
					<constructor-arg>
						<value>${memcached.server2.host}</value>
					</constructor-arg>
					<constructor-arg>
						<value>${memcached.server2.port}</value>
					</constructor-arg>
				</bean>
				<bean class="java.net.InetSocketAddress">
					<constructor-arg>
						<value>${memcached.server3.host}</value>
					</constructor-arg>
					<constructor-arg>
						<value>${memcached.server3.port}</value>
					</constructor-arg>
				</bean>
				<bean class="java.net.InetSocketAddress">
					<constructor-arg>
						<value>${memcached.server4.host}</value>
					</constructor-arg>
					<constructor-arg>
						<value>${memcached.server4.port}</value>
					</constructor-arg>
				</bean>
			</list>
		</constructor-arg>
		<constructor-arg>
			<list>
				<value>${memcached.server1.weight}</value>
				<value>${memcached.server2.weight}</value>
				<value>${memcached.server3.weight}</value>
				<value>${memcached.server4.weight}</value>
			</list>
		</constructor-arg>
		<property name="commandFactory">
			<bean class="net.rubyeye.xmemcached.command.TextCommandFactory" />
		</property>
		<property name="sessionLocator">
			<bean class="net.rubyeye.xmemcached.impl.KetamaMemcachedSessionLocator" />
		</property>
		<property name="transcoder">
			<bean class="net.rubyeye.xmemcached.transcoders.SerializingTranscoder" />
		</property>
	</bean>
	<!-- Use factory bean to build memcached client -->
	<bean
		id="memcachedClient"
		factory-bean="memcachedClientBuilder"
		factory-method="build"
		destroy-method="shutdown" />
</beans>

这里的memcachedClientBuilder节点完成MemcachedClientBuilder，然后通过memcachedClient节点配置factory-method，调用MemcachedClientBuilder的build()方法产生MemcachedClient，并配置destroy-method进行关闭。 

有了Spring容器支持，我们不需要在代码中进行配置，也不需要重复调用build()跟shutdown()方法，这些操作交给Spring来完成。 
代码如下： 

import static junit.framework.Assert.*;

import java.util.concurrent.TimeoutException;

import net.rubyeye.xmemcached.MemcachedClient;
import net.rubyeye.xmemcached.exception.MemcachedException;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MemcachedSpringTest {

	private ApplicationContext app;
	private MemcachedClient memcachedClient;

	@Before
	public void init() {
		app = new ClassPathXmlApplicationContext("applicationContext.xml");
		memcachedClient = (MemcachedClient) app.getBean("memcachedClient");
	}

	@Test
	public void test() {
		try {
			// 设置/获取
			memcachedClient.set("zlex", 36000, "set/get");
			assertEquals("set/get", memcachedClient.get("zlex"));

			// 替换
			memcachedClient.replace("zlex", 36000, "replace");
			assertEquals("replace", memcachedClient.get("zlex"));

			// 移除
			memcachedClient.delete("zlex");
			assertNull(memcachedClient.get("zlex"));
		} catch (TimeoutException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (MemcachedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}



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标签： memcached xmemcached与spring集成 memcached xmemcached与spring集成

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