Memcached安装教程及使用

Memcached

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

Table of contents

• 安装
• 使用
• 在spring中使用

安装

1. 下载下来memcached.exe
2. 切换到memcached.exe所在路径
3. 输入memcached -d install
4. win + r 输入 services.msc打开window服务
5. 随便选中一个输入memcached就可以查看到安装好的服务,右击启动它,然后关闭窗口

使用

1. 新建java工程或者maven工程
   
2. 导入三个必备的依赖,fastjson-1.2.3,slf4j-api-1.7.5,xmemcached-2.3.2

3. main方法中加入

    MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("127.0.0.1:11211")); builder.setSessionLocator(new KetamaMemcachedSessionLocator()); try { MemcachedClient memcachedClient =builder.build(); //在这里写入测试代码 memcachedClient.shutdown(); } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException e) { e.printStackTrace(); } catch (MemcachedException e) { e.printStackTrace(); } catch (TimeoutException e) { e.printStackTrace(); }

• 测试一定时间后数据是否还能取出来
• 永久时间,测试重启服务之后先前存储的数据是否还能取出来
• delete
• 自动增长

时效

 memcachedClient.set("testTime",2,"testTimeValue"); String testTime = memcachedClient.get("testTime"); System.out.println("testTime = " + testTime); TimeUnit.SECONDS.sleep(4); System.out.println("4s 过去了"); String valueExist = memcachedClient.get(testTime); System.out.println("valueExist = " + valueExist); 

输出:
testTime = testTimeValue
4s 过去了
valueExist = null

恢复

//存储,然后关闭掉服务 memcachedClient.set("test",0,"testValue"); String testTime=memcachedClient.get("test"); System.out.println("testTime="+testTime); System.out.println("存储成功"); 

输出:
testTime = testValue
存储成功

//关闭掉服务后的重启 String testTime = memcachedClient.get("test"); System.out.println("testTime = " + testTime); System.out.println("取值失败"); 

输出:
testTime = null
取值失败

delete

memcachedClient.set("test",0,"testValue"); String getVal = memcachedClient.get("test"); System.out.println("getVal = " + getVal); memcachedClient.delete("test"); System.out.println("after delete ..."); getVal = memcachedClient.get("test"); System.out.println("getVal = " + getVal); 

输出:
getVal = testValue
after delete ...
getVal = null

自动增长

//三个参数,第一个指定键,第二个指定递增的幅度大小,第三个指定当key不存在的情况下的初始值 for (int i = 0; i < 5; i++) { memcachedClient.incr("博客的赞",1,20); String point = memcachedClient.get("博客的赞"); System.out.println("point = " + point); } 

输出:
point = 20
point = 21
point = 22
point = 23
point = 24

关于incr的用法,值得警惕的是,它的值虽然看起来是一个数字,实际上正如代码中的String point = memcachedClient.get("博客的赞");
其实是一个字符串,所以会出现如下错误

memcachedClient.set("博客的赞1",0,10); int str = memcachedClient.get("博客的赞1"); System.out.println("str1 = " + str); memcachedClient.incr("博客的赞1",2,22); str = memcachedClient.get("博客的赞1"); System.out.println("str2 = " + str); 

输出:
net.rubyeye.xmemcached.exception.MemcachedClientException: cannot increment or decrement non-numeric value,key=博客的赞1
at net.rubyeye.xmemcached.command.Command.decodeError(Command.java:267)
..
at com.google.code.yanf4j.nio.impl.NioController.onRead(NioController.java:157)
at com.google.code.yanf4j.nio.impl.Reactor.dispatchEvent(Reactor.java:323)
at com.google.code.yanf4j.nio.impl.Reactor.run(Reactor.java:180)
str1 = 10

输出的顺序不同,注意输出的异常栈信息的第一条和后面的几条就指明nio.impl.Reactor.run,线程的,这儿就不深入展开了

spring

• 新建一个maven工程
• pom.xml
• 在resource中新建sping-config.xml
  
• spring单元测试代码骨架
• 测试代码

骨架

@RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = "classpath:spring-config.xml") public class TestMem { @Autowired private MemcachedClient memcachedClient; @Test public void test1(){ //测试代码部分 } } 

测试代码

memcachedClient.set("springData",3,"dataVal"); String str = memcachedClient.get("springData"); System.out.println("str = " + str); 

输出:
str = dataVal

还可以存储对象,不过该对象必须实现Serializable接口,不然会报错java.io.NotSerializableException: Teacher,

实现接口后

import lombok.Data; import java.io.Serializable; @Data public class Teacher implements Serializable { private int age; private String name; } 

关于@Data关我在另一篇博客中有介绍lombok

Teacher teacher = new Teacher(); teacher.setAge(3); teacher.setName("23"); memcachedClient.set("te", 0, teacher); Teacher teacher1 = memcachedClient.get("te"); System.out.println("teacher1 = " + teacher1);

输出:
teacher1 = Teacher(age=3, name=23)

pom.xml

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.selton</groupId> <artifactId>DemoMemSpring</artifactId> <version>1.0</version> <dependencies> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>4.3.11.RELEASE</version> </dependency> <dependency> <groupId>com.googlecode.xmemcached</groupId> <artifactId>xmemcached</artifactId> <version>2.0.0</version> <exclusions> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>4.3.11.RELEASE</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> </dependencies> </project> 

config

<?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:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd "> <bean id="memcachedClient" name="memcachedClient" class="net.rubyeye.xmemcached.utils.XMemcachedClientFactoryBean"> <property name="servers"> <!--配置端口,另加入的话,空格隔开--> <value>127.0.0.1:11211</value> </property> <property name="weights"> <list> <!--设置不同端口的权重,这里只有一个端口--> <value>1</value> </list> </property> <property name="sessionLocator"> <bean class="net.rubyeye.xmemcached.impl.KetamaMemcachedSessionLocator"></bean> </property> <property name="transcoder"> <bean class="net.rubyeye.xmemcached.transcoders.SerializingTranscoder" /> </property> <property name="bufferAllocator"> <bean class="net.rubyeye.xmemcached.buffer.SimpleBufferAllocator"></bean> </property> </bean> </beans>