XMemcached缓存系统
  fztgkkRjHIsV 2023年11月09日 14 0


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. 3000); 
4. //从memcached获取key对应的value,操作超时3秒


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. newXMemcachedClientBuilder(AddrUtil.getAddresses("10.180.44.224:11211 zhouxq:11211"),new int[]{1,3}); 
20. try { 
21.             MemcachedClient memcachedClient = builder.build(); 
22. "hello", 1, "Hello,xmemcached"); 
23. "hello",3000); // 
24. "hello=" + Value); 
25. //          memcachedClient.flushAll(); 
26. "hello",1, "zhouxq"); 
27. "hello")); 
28. //          memcachedClient.deleteWithNoReply("hello"); //删除 
29. "hello")); 
30. //          memcachedClient.delete("hello"); //删除 
31. //          Value = memcachedClient.get("hello"); 
32. //          System.out.println("hello=" + Value); 
33.              
34. "key",2,"someObject"); 
35. //从memcached获取key对应的value 
36. "key"); 
37.              
38. new Thread(); 
39.              t.start(); 
40. 1000); 
41. //从memcached获取key对应的value,操作超时3秒 
42. "key",1000); 
43.             System.out.println(someObject); 
44.              
45.              
46.             memcachedClient.shutdown(); 
47.              
48. catch (MemcachedException ex) { 
49. "MemcachedClient operation fail"); 
50.             ex.printStackTrace(); 
51. catch (TimeoutException xe) { 
52. "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 {
	@Test
	public 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2
			if (!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 client
			client.shutdown();
		} catch (IOException e) {
			System.err.println("Shutdown MemcachedClient fail");
			e.printStackTrace();
		}

	}

	@Test
	public 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");
	}

	@Test
	public 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));
	}

	@Test
	public 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 protocol
		builder.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 
	 */
	@Test
	public 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);
    }
}




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