标签：
什么是缓存
凡是位于速度相差较大的两种硬件/软件之间的，用于协调两者数据传输速度差异的结构，均可称之为缓存
分类
- 操作系统磁盘缓存，减少磁盘机械操作
- 数据库缓存，减少文件系统IO
- 应用程序缓存，减少数据库操作
- WEB服务器缓存，减少应用服务器请求
- 客户端浏览器缓存，减少网站访问
web相关
- 数据库缓存
- 系统配置参数缓存
- ORM提供的对象缓存、查询缓存
- 缓存服务器 EHCache、OSCache、JBossCache
- 通用缓存 memcached、radis
- 页面缓存（动态页面静态化、Servlet缓存、页面局部缓存）
- ajax查询结果缓存
- 浏览器缓存
- 代理服务器缓存
- CDN加速
适用范围
频繁访问且时效性不高的数据。例如：用户信息、菜单权限、功能权限、历史数据查询等
memcached缓存
Memcached 是一个高性能的分布式内存对象缓存系统，用于动态Web应用以减轻数据库负载。它通过在内存中缓存数据和对象来减少读取数据库的次数，从而提高动态、数据库驱动网站的速度。Memcached基于一个存储键/值对的hashmap。其守护进程（daemon ）是用C写的，但是客户端可以用任何语言来编写，并通过memcached协议与守护进程通信。[http://baike.baidu.com/view/794242.htm]
alisoft Memcached Client
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。所以，alisoft Memcached Client是一个支持分布式集群的管理客户端。
单客户端配置
<?xml version="1.0" encoding="UTF-8"?>
<memcached>
<client name="mclient0" compressEnable="true" defaultEncoding="UTF-8" socketpool="pool0">
<errorHandler>com.alisoft.xplatform.asf.cache.memcached.MemcachedErrorHandler</errorHandler>
</client>
<socketpool name="pool0" failover="true" initConn="5" minConn="5" maxConn="250" maintSleep="5000" nagle="false"
socketTO="3000" aliveCheck="true">
<servers>127.0.0.1:11211,127.0.0.1:11212</servers>
<weights>3,7</weights>
</socketpool>
</memcached>创建 client的标签
name 属性是程序中使用Cache的唯一标识。
socketpool 属性将会关联到后面的socketpool配置。
errorHandler 可选，用来处理出错情况。注意在Tag中不要使用空格或者Tab键。
name 属性和client 配置中的socketpool 属性相关联。
maintSleep属性是后台线程管理SocketIO池的检查间隔时间，如果设置为0，则表明不需要后台线程维护SocketIO线程池，默认需要管理。
socketTO 属性是Socket操作超时配置，单位ms。
aliveCheck 属性表示在使用Socket以前是否先检查Socket状态。
创建 weights 标签作为socketPool的子标签(可选),它表明了上面设置的服务器实例的Load权重. 例如 <weights>3,7</weights>表示30% load 在 127.0.0.1:11211, 70% load 在 127.0.0.1:11212
/**
* lincl
* 2016年7月12日 下午4:56:35
*
*/
package com.lezic.core.cache.memcached;
import java.util.Calendar;
import org.junit.AfterClass;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;
import com.alisoft.xplatform.asf.cache.ICacheManager;
import com.alisoft.xplatform.asf.cache.IMemcachedCache;
import com.alisoft.xplatform.asf.cache.memcached.CacheUtil;
import com.alisoft.xplatform.asf.cache.memcached.MemcachedCacheManager;
/**
* 单客户端
*
* @author lincl
*
*/
public class MemcachedClient {
static ICacheManager<IMemcachedCache> manager;
/**
* 初始化上下文，加载配置文件
*
* @throws Exception
*/
@BeforeClass
public static void setUpBeforeClass() throws Exception {
manager = CacheUtil.getCacheManager(IMemcachedCache.class, MemcachedCacheManager.class.getName());
manager.setConfigFile("memcached0.xml");
manager.setResponseStatInterval(5 * 1000);
manager.start();
}
/**
* 摧毁管理器
*
* @throws java.lang.Exception
*/
@AfterClass
public static void tearDownAfterClass() throws Exception {
manager.stop();
}
/**
* 测试获取
*
*/
@Test
public void testGet() {
try {
IMemcachedCache cache = manager.getCache("mclient0");
cache.remove("key1");
cache.remove("key2你好");
cache.put("key1", "1");
cache.put("key2你好", "你好123");
Assert.assertEquals(cache.get("key1"), "1");
Assert.assertEquals(cache.get("key2你好"), "你好123");
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
/**
* 测试删除
*/
@Test
public void testRemove() {
try {
IMemcachedCache cache = manager.getCache("mclient0");
cache.remove("key1");
cache.put("key1", "value1");
Assert.assertEquals(cache.get("key1"), "value1");
cache.remove("key1");
Assert.assertNull(cache.get("key1"));
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
/**
* 测试是否包含key
*/
@Test
public void testContainsKey() {
try {
IMemcachedCache cache = manager.getCache("mclient0");
cache.remove("key1");
cache.put("key1", "value1");
Assert.assertTrue(cache.containsKey("key1"));
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
@Test
public void testAdd() {
try {
IMemcachedCache cache = manager.getCache("mclient0");
cache.remove("key1");
Assert.assertTrue(cache.add("key1", "value1"));
Assert.assertFalse(cache.add("key1", "value1"));
Assert.assertEquals(cache.get("key1"), "value1");
cache.remove("key1");
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
/**
* Test method for {@link com.alisoft.xplatform.asf.cache.ICache#clear()}.
*/
@Test
public void testClear() {
try {
IMemcachedCache cache = manager.getCache("mclient0");
cache.remove("key1");
cache.put("key1", "value1");
Assert.assertEquals(cache.get("key1"), "value1");
cache.clear();
Assert.assertNull(cache.get("key1"));
Thread.sleep(2000);
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
/**
* 保存有有效期的数据 Test method for
* {@link com.alisoft.xplatform.asf.cache.ICache#put(java.lang.Object, java.lang.Object, java.util.Date)} .
*/
@Test
public void testPutKVDate() {
try {
IMemcachedCache cache = manager.getCache("mclient0");
Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.SECOND, 5);
cache.remove("key1");
cache.put("key1", "value1", calendar.getTime());
Assert.assertEquals(cache.get("key1"), "value1");
Thread.sleep(5 * 1000 + 1000);
Assert.assertNull(cache.get("key1"));
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
}
9.集群配置
<?xml version="1.0" encoding="UTF-8"?>
<memcached>
<client name="mclient" compressEnable="true" defaultEncoding="UTF-8" socketpool="pool0">
<errorHandler>com.alisoft.xplatform.asf.cache.memcached.MemcachedErrorHandler</errorHandler>
</client>
<client name="mclient1" compressEnable="true" defaultEncoding="UTF-8" socketpool="pool1">
<errorHandler>com.alisoft.xplatform.asf.cache.memcached.MemcachedErrorHandler</errorHandler>
</client>
<client name="mclient2" compressEnable="true" defaultEncoding="UTF-8" socketpool="pool2">
<errorHandler>com.alisoft.xplatform.asf.cache.memcached.MemcachedErrorHandler</errorHandler>
</client>
<client name="mclient3" compressEnable="true" defaultEncoding="UTF-8" socketpool="pool3">
<errorHandler>com.alisoft.xplatform.asf.cache.memcached.MemcachedErrorHandler</errorHandler>
</client>
<client name="mclient4" compressEnable="true" defaultEncoding="UTF-8" socketpool="pool4">
<errorHandler>com.alisoft.xplatform.asf.cache.memcached.MemcachedErrorHandler</errorHandler>
</client>
<socketpool name="pool0" failover="true" initConn="5" minConn="5" maxConn="250" maintSleep="0" nagle="false"
socketTO="3000" aliveCheck="true">
<servers>127.0.0.1:11210</servers>
</socketpool>
<socketpool name="pool1" failover="true" initConn="5" minConn="5" maxConn="250" maintSleep="0" nagle="false"
socketTO="3000" aliveCheck="true">
<servers>127.0.0.1:11211</servers>
</socketpool>
<socketpool name="pool2" failover="true" initConn="5" minConn="5" maxConn="250" maintSleep="0" nagle="false"
socketTO="3000" aliveCheck="true">
<servers>127.0.0.1:11212</servers>
</socketpool>
<socketpool name="pool3" failover="true" initConn="5" minConn="5" maxConn="250" maintSleep="0" nagle="false"
socketTO="3000" aliveCheck="true">
<servers>127.0.0.1:11213</servers>
</socketpool>
<socketpool name="pool4" failover="true" initConn="5" minConn="5" maxConn="250" maintSleep="0" nagle="false"
socketTO="3000" aliveCheck="true">
<servers>127.0.0.1:11214</servers>
</socketpool>
<cluster name="cluster1" mode="active">
//mode = active,standby
<memCachedClients>mclient1,mclient2</memCachedClients>
</cluster>
<cluster name="cluster2" mode="standby">
//mode = active,standby
<memCachedClients>mclient3,mclient4</memCachedClients>
</cluster>
</memcached>标签作为cluster的子标签，然后将客户端配置到memCachedClients 标签中
集群当前的特性
- 集群中多节点软负载均衡。（当前采用简单的Hash算法加取余来分发数据）
- 数据在多节点上异步冗余存储。（防止数据丢失最基本要求）
- 节点不可用切换功能。（当根据算法分发到某一失败节点时可以转向到其他可用节点）
- 节点恢复可用后数据Lazy复制。（当A,B两台机器作为集群的时候，如果A出现了问题，系统会去B获取数据，当A正常以后，如果应用在A中没有拿到数据可以去B获取数据，并且复制到A上，这种方式也是一种lazy的复制。）
/**
*
*/
package com.alisoft.xplatform.asf.cache;
import org.junit.AfterClass;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Ignore;
import org.junit.Test;
import com.alisoft.xplatform.asf.cache.memcached.CacheUtil;
import com.alisoft.xplatform.asf.cache.memcached.MemcachedCacheManager;
/**
* 集群测试类
* @author wenchu.cenwc
*
*/
public class MemcachedClusterTest {
static ICacheManager<IMemcachedCache> manager;
/**
* @throws java.lang.Exception
*/
@BeforeClass
public static void setUpBeforeClass() throws Exception {
manager = CacheUtil.getCacheManager(IMemcachedCache.class, MemcachedCacheManager.class.getName());
manager.setConfigFile("memcached_cluster.xml");
manager.start();
}
/**
* @throws java.lang.Exception
*/
@AfterClass
public static void tearDownAfterClass() throws Exception {
manager.stop();
}
@Test
public void testActiveMode() {
try {
IMemcachedCache cache1 = manager.getCache("mclient1");
IMemcachedCache cache2 = manager.getCache("mclient2");
cache1.put("key1", "value1");
cache1.put("key2", "value2");
cache1.put("key3", "value3");
cache1.put("key4", "value4");
cache1.put("key5", "value5");
cache1.put("key6", "value6");
// 模拟mclient1失效(结束服务端)，有出错日志在控制台打印
Assert.assertEquals(cache1.get("key1"), "value1");
Assert.assertEquals(cache1.get("key2"), "value2");
Assert.assertEquals(cache1.get("key3"), "value3");
Assert.assertEquals(cache1.get("key4"), "value4");
Assert.assertEquals(cache1.get("key5"), "value5");
Assert.assertEquals(cache1.get("key6"), "value6");
Assert.assertEquals(cache2.get("key1"), "value1");
Assert.assertEquals(cache2.get("key2"), "value2");
Assert.assertEquals(cache2.get("key3"), "value3");
Assert.assertEquals(cache2.get("key4"), "value4");
Assert.assertEquals(cache2.get("key5"), "value5");
Assert.assertEquals(cache2.get("key6"), "value6");
// 恢复mclient1，无出错日志在控制台打印
Assert.assertEquals(cache1.get("key1"), "value1");
Assert.assertEquals(cache1.get("key2"), "value2");
Assert.assertEquals(cache1.get("key3"), "value3");
Assert.assertEquals(cache1.get("key4"), "value4");
Assert.assertEquals(cache1.get("key5"), "value5");
Assert.assertEquals(cache1.get("key6"), "value6");
Assert.assertEquals(cache2.get("key1"), "value1");
Assert.assertEquals(cache2.get("key2"), "value2");
Assert.assertEquals(cache2.get("key3"), "value3");
Assert.assertEquals(cache2.get("key4"), "value4");
Assert.assertEquals(cache2.get("key5"), "value5");
Assert.assertEquals(cache2.get("key6"), "value6");
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
@Test
@Ignore
public void testStandByMode() {
IMemcachedCache cache1 = manager.getCache("mclient3");
IMemcachedCache cache2 = manager.getCache("mclient4");
cache1.put("key1", "value1");
cache1.put("key2", "value2");
cache1.put("key3", "value3");
cache1.put("key4", "value4");
cache1.put("key5", "value5");
cache1.put("key6", "value6");
// 模拟mclient1失效(结束服务端)，有出错日志在控制台打印
Assert.assertEquals(cache1.get("key1"), "value1");
Assert.assertEquals(cache1.get("key2"), "value2");
Assert.assertEquals(cache1.get("key3"), "value3");
Assert.assertEquals(cache1.get("key4"), "value4");
Assert.assertEquals(cache1.get("key5"), "value5");
Assert.assertEquals(cache1.get("key6"), "value6");
Assert.assertEquals(cache2.get("key1"), "value1");
Assert.assertEquals(cache2.get("key2"), "value2");
Assert.assertEquals(cache2.get("key3"), "value3");
Assert.assertEquals(cache2.get("key4"), "value4");
Assert.assertEquals(cache2.get("key5"), "value5");
Assert.assertEquals(cache2.get("key6"), "value6");
// 恢复mclient1，无出错日志在控制台打印
Assert.assertNull(cache1.get("key1"));
Assert.assertEquals(cache1.get("key2"), "value2");
Assert.assertNull(cache1.get("key3"));
Assert.assertEquals(cache1.get("key4"), "value4");
Assert.assertNull(cache1.get("key5"));
Assert.assertEquals(cache1.get("key6"), "value6");
Assert.assertNull(cache2.get("key1"));
Assert.assertEquals(cache2.get("key2"), "value2");
Assert.assertNull(cache2.get("key3"));
Assert.assertEquals(cache2.get("key4"), "value4");
Assert.assertNull(cache2.get("key5"));
Assert.assertEquals(cache2.get("key6"), "value6");
}
/**
* 集群复制
*
*/
@Test
public void testClusterCopy() {
try {
IMemcachedCache cache = manager.getCache("mclient");
IMemcachedCache cache1 = manager.getCache("mclient1");
IMemcachedCache cache2 = manager.getCache("mclient2");
cache.put("key1", "value1");
cache.put("key2", "value2");
cache.put("key3", "value3");
cache.put("key4", "value4");
cache.put("key5", "value5");
cache.put("key6", "value6");
cache1.remove("key1");
cache1.remove("key2");
cache1.remove("key3");
cache1.remove("key4");
cache1.remove("key5");
cache1.remove("key6");
cache2.remove("key1");
cache2.remove("key2");
cache2.remove("key3");
cache2.remove("key4");
cache2.remove("key5");
cache2.remove("key6");
manager.clusterCopy("mclient", "cluster1");
Assert.assertEquals(cache1.get("key1"), "value1");
Assert.assertEquals(cache1.get("key2"), "value2");
Assert.assertEquals(cache1.get("key3"), "value3");
Assert.assertEquals(cache1.get("key4"), "value4");
Assert.assertEquals(cache1.get("key5"), "value5");
Assert.assertEquals(cache1.get("key6"), "value6");
Assert.assertEquals(cache2.get("key1"), "value1");
Assert.assertEquals(cache2.get("key2"), "value2");
Assert.assertEquals(cache2.get("key3"), "value3");
Assert.assertEquals(cache2.get("key4"), "value4");
Assert.assertEquals(cache2.get("key5"), "value5");
Assert.assertEquals(cache2.get("key6"), "value6");
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
@Test
public void testReload() {
try {
IMemcachedCache cache = manager.getCache("mclient");
IMemcachedCache cache1 = manager.getCache("mclient1");
IMemcachedCache cache2 = manager.getCache("mclient2");
IMemcachedCache cache5 = manager.getCache("mclient5");
IMemcachedCache cache6 = manager.getCache("mclient6");
Assert.assertNull(cache5);
Assert.assertNull(cache6);
cache.clear();
Thread.sleep(1000);
cache1.clear();
Thread.sleep(1000);
cache2.clear();
Thread.sleep(1000);
cache.put("key1", "1");
cache1.put("key2", "2");
Assert.assertNull(cache.get("key2"));
Assert.assertNull(cache1.get("key1"));
Thread.sleep(2000);
// manager.reload("http://10.2.226.41/sip/memcached_cluster2.xml");
manager.reload("memcached_cluster2.xml");
Thread.sleep(2000);
cache1 = manager.getCache("mclient1");
cache2 = manager.getCache("mclient2");
cache5 = manager.getCache("mclient5");
cache6 = manager.getCache("mclient6");
Assert.assertNull(cache1);
Assert.assertNull(cache2);
Assert.assertNotNull(cache5);
Assert.assertNotNull(cache6);
cache5.clear();
Thread.sleep(1000);
cache6.clear();
Thread.sleep(3000);
manager.reload("memcached_cluster3.xml");
Thread.sleep(2000);
cache = manager.getCache("mclient");
cache1 = manager.getCache("mclient1");
cache2 = manager.getCache("mclient2");
cache5 = manager.getCache("mclient5");
cache6 = manager.getCache("mclient6");
Assert.assertEquals(cache.get("key2"), "2");
Assert.assertEquals(cache1.get("key1"), "1");
Assert.assertEquals(cache2.get("key2"), "2");
Assert.assertEquals(cache5.get("key2"), "2");
Assert.assertNull(cache2.get("key1"));
Assert.assertNull(cache5.get("key1"));
Assert.assertNull(cache6.get("key1"));
Assert.assertNull(cache6.get("key2"));
} catch (Exception ex) {
ex.printStackTrace();
Assert.assertTrue(false);
}
}
}
标签：
原文地址：http://blog.csdn.net/cielo88/article/details/51889919
