Memcached安装教程及使用-白红宇

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

安装

下载下来memcached.exe

切换到memcached.exe所在路径

输入memcached -d install

win + r 输入 services.msc打开window服务

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

新建java工程或者maven工程

导入三个必备的依赖,fastjson-1.2.3,slf4j-api-1.7.5,xmemcached-2.3.2

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(); }

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

在resource中新建

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;@Datapublic 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

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


    
        
     
      4.0.0
         
     
      com.selton
         
     
      DemoMemSpring
         
     
      1.0
         
             
                  
       
        org.projectlombok
                   
       
        lombok
                   
       
        1.18.0
                   
       
        provided
               
              
                  
       
        org.springframework
                   
       
        spring-context
                   
       
        4.3.11.RELEASE
               
              
                  
       
        com.googlecode.xmemcached
                   
       
        xmemcached
                   
       
        2.0.0
                   
                       
                            
         
          org.springframework
                             
         
          spring-context
                         
                    
               
              
                  
       
        org.springframework
                   
       
        spring-test
                   
       
        4.3.11.RELEASE
               
              
                  
       
        junit
                   
       
        junit
                   
       
        4.12
                   
       
        test

config


    
        
             
                  
                   
       
        127.0.0.1:11211
               
              
                  
                       
                        
        
         1