XMemcached缓存系统

XMemcached 学习整理

1、首先要把server 启动：对应到相应的目录下memcached.exe –start
2、依赖slf4j.jar包，下载slf4j 把D:\library\slf4j-1.5.5\slf4j-simple-1.5.5.jar
和D:\library\slf4j-1.5.5\slf4j-simple-1.5.5.jar放在classpath路径下
3、Memcache第一次会把数据放在内存当中，每次执行的时候如果数据没有变就不更新，直接从内存当中取。
4、如果server停掉，存在内存中的数据会消失
5、替换键对应的数值
   Replace(“key”,”value”);

Java代码  

1. MemcachedClientBuilder builder = newXMemcachedClientBuilder(AddrUtil.getAddresses("10.180.44.224:11211 zhouxq:11211"),new int[]{1,3}); 

MemcachedClientBuilder 5个构造方法
构造方法
XMemcachedClientBuilder(List/Map address,int[] weight)
Address 可以是：

Java代码  

1. java.util.Map<java.net.InetSocketAddress,java.net.InetSocketAddress> addressMap 
2. java.util.List<java.net.InetSocketAddress> addressList  

weight 与servers对应的节点的权重
weight 可以有也可无
weight 值大则权重大，否则小

XMemcached允许通过设置节点的权重来调节memcached的负载，设置的权重越高，该memcached节点存储的数据将越多，所承受的负载越大。
xmemcached的权重是通过复制连接的多个引用来实现的，比如权重为3，那么就复制3个同一个连接的引用放在集合中让MemcachedSessionLocator查找。
改变节点权重，可以通过setServerWeight方法：

Java代码  

1. public void setServerWeight(String server, int weight); 

传入一个int数组，里面的元素就是节点对应的权重值，比如这里设置"10.180.44.224:1121"节点的权重为1，而"zhouxq:11211"的权重为3。
类似的XMemcachedClient()和XMemcachedClientBuilder相同

设置连接池大小

Java代码  

1. builder.setConnectionPoolSize(5); 

连接池通常不建议设置太大，我推荐在0-30之间为好，太大则浪费系统资源，太小无法达到分担负载的目的。
设置失败模式 如果服务出现down的情况，会报出异常，直到服务正常

Java代码  

1. builder.setFailureMode(true); 

使用二进制文件

Java代码  

1. builder.setCommandFactory(new BinaryCommandFactory());  

7、
存储数据是通过set方法，它有三个参数，第一个是存储的key名称，第二个是expire时间（单位秒），超过这个时间,memcached将这个数据替换出去，0表示永久存储（默认是一个月），第三个参数就是实际存储的数据，可以是任意的java可序列化类型。

Java代码  

1. Thread  t = new Thread(); 
2.          t.start(); 
3.          t.sleep(3000); 
4.     //从memcached获取key对应的value,操作超时3秒 

[java] view plaincopy

someObject=memcachedClient.get("key",3000);后面的对应的是毫秒
超时后得到的key对应的值为null
8、与Spring框架集成
通过XMemcachedClientFactoryBean类，即可与spring框架集成

测试代码

Java代码  

1. package com.test.xmemcache; 
2.  
3. import java.io.IOException; 
4. import java.util.concurrent.TimeoutException; 
5.  
6. import net.rubyeye.xmemcached.MemcachedClient; 
7. import net.rubyeye.xmemcached.MemcachedClientBuilder; 
8. import net.rubyeye.xmemcached.XMemcachedClientBuilder; 
9. import net.rubyeye.xmemcached.exception.MemcachedException; 
10. import net.rubyeye.xmemcached.utils.AddrUtil; 
11.  
12. public class XmemcacheTest { 
13.  
14.     /**
15.      * @param args
16.      */ 
17.     public static void main(String[] args) { 
18.         // TODO Auto-generated method stub 
19.         MemcachedClientBuilder builder = newXMemcachedClientBuilder(AddrUtil.getAddresses("10.180.44.224:11211 zhouxq:11211"),new int[]{1,3}); 
20.         try { 
21.             MemcachedClient memcachedClient = builder.build(); 
22.             memcachedClient.set("hello", 1, "Hello,xmemcached"); 
23.             String Value=memcachedClient.get("hello",3000); // 
24.             System.out.println("hello=" + Value); 
25. //          memcachedClient.flushAll(); 
26.             memcachedClient.replace("hello",1, "zhouxq"); 
27.             System.out.println(memcachedClient.get("hello")); 
28. //          memcachedClient.deleteWithNoReply("hello"); //删除 
29.             System.out.println(memcachedClient.get("hello")); 
30. //          memcachedClient.delete("hello"); //删除 
31. //          Value = memcachedClient.get("hello"); 
32. //          System.out.println("hello=" + Value); 
33.              
34.             memcachedClient.set("key",2,"someObject"); 
35.             //从memcached获取key对应的value 
36.             Object someObject=memcachedClient.get("key"); 
37.              
38.              Thread  t = new Thread(); 
39.              t.start(); 
40.              t.sleep(1000); 
41.             //从memcached获取key对应的value,操作超时3秒 
42.             someObject=memcachedClient.get("key",1000); 
43.             System.out.println(someObject); 
44.              
45.              
46.             memcachedClient.shutdown(); 
47.              
48.         } catch (MemcachedException ex) { 
49.             System.err.println("MemcachedClient operation fail"); 
50.             ex.printStackTrace(); 
51.         } catch (TimeoutException xe) { 
52.             System.err.println("MemcachedClient operation timeout"); 
53.             xe.printStackTrace(); 
54.         } catch (InterruptedException e) { 
55.             // ignore 
56.         } catch (IOException e) { 
57.             // TODO Auto-generated catch block 
58.             e.printStackTrace(); 
59.         } 
60.     } 
61.  
62. } 

总结

Memcached 是一个高性能的分布式内存对象的key-value缓存系统，用于动态Web应用以减轻数据库负载，现在也有很多人将它作为内存式数据库在使用，memcached通过它的自定义协议与客户端交互，而XMemcached就是它的一个java客户端实现。

 

XMemcached使用示例（本示例基于xmemcached-1.3.8.jar），总结一个，如下：

package com.wujintao.memcached;import java.io.IOException;import java.util.concurrent.TimeoutException;import net.rubyeye.xmemcached.Counter;import net.rubyeye.xmemcached.GetsResponse;import net.rubyeye.xmemcached.MemcachedClient;import net.rubyeye.xmemcached.MemcachedClientBuilder;import net.rubyeye.xmemcached.XMemcachedClientBuilder;import net.rubyeye.xmemcached.auth.AuthInfo;import net.rubyeye.xmemcached.command.BinaryCommandFactory;import net.rubyeye.xmemcached.exception.MemcachedException;import net.rubyeye.xmemcached.transcoders.StringTranscoder;import net.rubyeye.xmemcached.utils.AddrUtil;import org.junit.Test;import com.wujintao.redis.util.MD5Util;public class TestCase {@Testpublic void test1() throws IOException {MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:11211"));// AddrUtil.getAddresses("server1:11211 server2:11211")               // 宕机报警                 builder.setFailureMode(true);                // 使用二进制文件                 builder.setCommandFactory(new BinaryCommandFactory());            /**              * 设置连接池大小，即客户端个数              * In a high concurrent enviroment,you may want to pool memcached clients.              * But a xmemcached client has to start a reactor thread and some thread pools,              * if you create too many clients,the cost is very large.               * Xmemcached supports connection pool instreadof client pool.              * you can create more connections to one or more memcached servers,              * and these connections share the same reactor and thread pools,              * it will reduce the cost of system.              *  默认的pool size是1。设置这一数值不一定能提高性能，请依据你的项目的测试结果为准。初步的测试表明只有在大并发下才有提升。              *  设置连接池的一个不良后果就是，同一个memcached的连接之间的数据更新并非同步的              *  因此你的应用需要自己保证数据更新的原子性（采用CAS或者数据之间毫无关联）。              */                  builder.setConnectionPoolSize(10);  MemcachedClient client = builder.build();try {/** * 第一个是存储的key名称， * 第二个是expire时间（单位秒），超过这个时间,memcached将这个数据替换出去，0表示永久存储（默认是一个月) * 第三个参数就是实际存储的数据 */client.set("hello", 0, "Hello,xmemcached");String value = client.get("hello");System.out.println("hello=" + value);client.delete("hello");value = client.get("hello");System.out.println("hello=" + value);// value=client.get(“hello”,3000);/** * Memcached是通过cas协议实现原子更新，所谓原子更新就是compare and set， * 原理类似乐观锁，每次请求存储某个数据同时要附带一个cas值， memcached比对这个cas值与当前存储数据的cas值是否相等， * 如果相等就让新的数据覆盖老的数据，如果不相等就认为更新失败， 这在并发环境下特别有用 */GetsResponse<Integer> result = client.gets("a");long cas = result.getCas();// 尝试将a的值更新为2if (!client.cas("a", 0, 2, cas)) {System.err.println("cas error");}} catch (MemcachedException e) {System.err.println("MemcachedClient operation fail");e.printStackTrace();} catch (TimeoutException e) {System.err.println("MemcachedClient operation timeout");e.printStackTrace();} catch (InterruptedException e) {// ignore}try {// close memcached clientclient.shutdown();} catch (IOException e) {System.err.println("Shutdown MemcachedClient fail");e.printStackTrace();}}@Testpublic void test2() throws TimeoutException, InterruptedException,MemcachedException, IOException {MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:11211"));MemcachedClient client = builder.build();client.flushAll();if (!client.set("hello", 0, "world")) {System.err.println("set error");}if (client.add("hello", 0, "dennis")) {System.err.println("Add error,key is existed");}if (!client.replace("hello", 0, "dennis")) {System.err.println("replace error");}client.append("hello", " good");client.prepend("hello", "hello ");String name = client.get("hello", new StringTranscoder());System.out.println(name);/** * 而删除数据则是通过deleteWithNoReply方法，这个方法删除数据并且告诉memcached * 不用返回应答，因此这个方法不会等待应答直接返回，特别适合于批量处理 */client.deleteWithNoReply("hello");}@Testpublic void incrDecr() throws IOException, TimeoutException,InterruptedException, MemcachedException {MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:11211"));MemcachedClient client = builder.build();/** * 第一个参数指定递增的key名称， 第二个参数指定递增的幅度大小， 第三个参数指定当key不存在的情况下的初始值。 * 两个参数的重载方法省略了第三个参数，默认指定为0。 */assert (1 == client.incr("a", 5, 1));assert (6 == client.incr("a", 5));assert (10 == client.incr("a", 4));assert (9 == client.decr("a", 1));assert (7 == client.decr("a", 2));}@Testpublic void counter() throws Exception {MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:11211"));MemcachedClient client = builder.build();Counter counter = client.getCounter("counter", 0);counter.incrementAndGet();counter.decrementAndGet();counter.addAndGet(-10);}public void auth() throws Exception {MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:11211"));builder.addAuthInfo(AddrUtil.getOneAddress("localhost:11211"),AuthInfo.typical("cacheuser", "123456"));// Must use binary protocolbuilder.setCommandFactory(new BinaryCommandFactory());MemcachedClient client = builder.build();}public void nioPool() throws Exception {MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:11211"));builder.setConnectionPoolSize(5);}/**     *这里应该安装kestrel消息服务器，才能使用如下API生效 * @throws IOException * @throws MemcachedException  * @throws InterruptedException  * @throws TimeoutException  */@Testpublic void testGet() throws IOException, TimeoutException, InterruptedException, MemcachedException{MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:11212"));MemcachedClient client = builder.build();String value = client.get("1");System.out.println("hello=" + value);}@Test    public void testGet2() throws IOException, TimeoutException, InterruptedException, MemcachedException{        MemcachedClientBuilder builder = new XMemcachedClientBuilder(                AddrUtil.getAddresses("localhost:11212"));        MemcachedClient client = builder.build();        String value = client.get("srp_"+MD5Util.MD5("3rdsearch_周杰伦"));        System.out.println(value);    }}