XMemcached是memcached的一个java客户端，基于java nio，支持memcached的所有协议。本文简要介绍XMemcached的基本使用。

一、添加依赖

com.googlecode.xmemcached

xmemcached

2.4.0

二、创建Java文件

UserModel.java

packagecom.czhappy.memcached_project.vo;importjava.io.Serializable;public class UserModel implementsSerializable{private intuuid;privateString userName;private intage;publicUserModel(){}public UserModel(int uuid, String userName, intage) {this.uuid =uuid;this.userName =userName;this.age =age;

}public intgetUuid() {returnuuid;

}public void setUuid(intuuid) {this.uuid =uuid;

}publicString getUserName() {returnuserName;

}public voidsetUserName(String userName) {this.userName =userName;

}public intgetAge() {returnage;

}public void setAge(intage) {this.age =age;

}

@OverridepublicString toString() {return "UserModel{" +

"uuid=" + uuid +

", userName='" + userName + '\'' +

", age=" + age +

'}';

}

}

ConnectonHelper.java

packagecom.czhappy.memcached_project.utils;importnet.rubyeye.xmemcached.MemcachedClient;importnet.rubyeye.xmemcached.MemcachedClientBuilder;importnet.rubyeye.xmemcached.XMemcachedClient;importnet.rubyeye.xmemcached.XMemcachedClientBuilder;importnet.rubyeye.xmemcached.utils.AddrUtil;importorg.junit.Test;importjava.io.IOException;importjava.net.InetSocketAddress;importjava.util.Map;public classConnectonHelper {public staticMemcachedClient getClient(){//连接配置

MemcachedClientBuilder memcachedClientBuilder =

new XMemcachedClientBuilder(AddrUtil.getAddresses("192.168.84.128:2222"));//创建与服务端之间的连接[ip地址，端口号，用户名和密码]//获取操作业务对象

MemcachedClient memcachedClient = null;try{

memcachedClient=memcachedClientBuilder.build();

}catch(IOException e) {

e.printStackTrace();

}returnmemcachedClient;

}public static void main(String[] args) throwsException {//连接配置//创建与服务端之间的连接[ip地址，端口号，用户名和密码]//获取操作业务对象

MemcachedClient memcachedClient =

new XMemcachedClient("192.168.84.128",2222);//操作业务

String str = "Hello World!";boolean isSuccess = memcachedClient.set("k1", 3600, str);

String value= memcachedClient.get("k1");

System.out.println("value="+value);//关闭与服务端连接

memcachedClient.shutdown();

}

}

执行Main方法，判断是否连接成功：

三、基本使用

定义MemcachedClient

static MemcachedClient client = ConnectonHelper.getClient();

定义查询【get/gets】方法

public static void showQuery(String key)throwsException{

UserModel um=client.get(key);

System.out.println("get方法获取的值="+um);

}

定义新增【set,add】方法

public static void showAdd(UserModel um) throwsException {

client.set("set-user:"+um.getUuid(),3600,um);

client.add("add-user:"+um.getUuid(),3600,um);

}

测试：

UserModel um = new UserModel(1, "李四", 55);

showAdd(um);

showQuery("set-user:1");

showQuery("add-user:1");

查询测试结果：

我们通过命令行添加k1，用来测试update方法：

定义修改【replace,append,prepend】方法

public static void showUpdate(UserModel um) throwsException{

client.replace("set-user:"+um.getUuid(),3600,um);//Hi! asd chenz

client.prepend("k1","Hi! ");

client.append("k1"," chenz");

}

测试：

UserModel um = new UserModel(1, "王五", 60);

showUpdate(um);

查询测试结果：

showQuery("set-user:1");

定义删除【delete】方法

public static void showDelete(String key)throwsException{boolean isSuccess =client.delete(key);

System.out.println("delete结果="+isSuccess);

}

测试删除：

showDelete("k1");

定义检查更新【cas】方法

public static void showCAS(UserModel um)throwsException{

String key= "set-user:" +um.getUuid();//第一件事先获取版本号

GetsResponse userModelGetsResponse =showGets(key);long cas =userModelGetsResponse.getCas();// //演示cas版本是否生效//UserModel um1 = new UserModel(1,"happy admin",20);//showUpdate(um1);//进行更新操作

boolean isSuccess = client.cas(key, 3600, um, cas);

System.out.println("更新结果="+isSuccess);

}

测试：

UserModel um = new UserModel(1, "科比", 35);

showCAS(um);

查询结果：

showQuery("set-user:1");

问题：在获取版本号之后及cas数据之前，这一段存在时间差，可能会因为版本号的问题导致操作失败，因此，XMemcached特地封装了xmcas

public static void showXMCAS() throwsException {//操作XMemcached提供的CAS操作

client.cas("k1", new CASOperation() {//重试次数

public intgetMaxTries() {returnInteger.MAX_VALUE;

}//修改内容

public String getNewValue(longcas, String currentValue) {return "Hi ! "+currentValue + "！！！！！";

}

});

}

定义数值操作【incr/decr】方法

public static void showNumChange()throwsException{

MemcachedClient memcachedClient=ConnectonHelper.getClient();long result = memcachedClient.incr("k5",5,10);

System.out.println("result1 = "+result);

result= memcachedClient.incr("k5",40,10);

System.out.println("result2 = "+result);

result= memcachedClient.decr("k5",25,10);

System.out.println("result3 = "+result);

result= memcachedClient.decr("k5",30,10);

System.out.println("result4 = "+result);

}

测试结果：

针对上述结果，给出以下解释说明：

/*long result = memcachedClient.incr("k5",5,10);

result1 = 10 -> API【如果key不存在，则第三个参数为初始值】

result = memcachedClient.incr("k5",40,10);

result2 = 50 -> 如果key存在，则进行递增或递减操作

result = memcachedClient.decr("k5",25,10);

result3 = 25 -> 如果key存在，则进行递增或递减操作

result = memcachedClient.decr("k5",30,10);

result4 = 0 -> decr是不能减出负数*/

获取所有的key列表

public static void showKeyIterator() throwsException{

KeyIterator keyIterator= client.getKeyIterator(AddrUtil.getOneAddress("192.168.84.128:2222"));while(keyIterator.hasNext()){

System.out.println("keys="+keyIterator.next());

}

}

XMemcached提供的计数器

public static void showCounter() throwsException {

Counter counter= new Counter(client,"k5",10);long c1 =counter.incrementAndGet();

System.out.println("c1="+c1);long c2 =counter.decrementAndGet();

System.out.println("c2="+c2);long c3 = counter.addAndGet(88);

System.out.println("c3="+c3);long c4 = counter.addAndGet(-10000);

System.out.println("c4="+c4);

counter.set(50);long c5 =counter.get();

System.out.println("c5="+c5);

String key=counter.getKey();

System.out.println("key="+key);

}

测试结果：

更新数据过期时间

一般采用：

/*

1、先存入一条数据 【设置过过期时间 10个小时】

2、先获取待更新过期时间的数据

3、再通过 replace | set 方法，将数据修改回去，同时设置过期时间

*/

通过XMemcached，我们这样做：

/*

1、先存入一条数据 【设置过过期时间 10个小时】

2、直接使用touch进行更新过期时间

*/

public static void showTouch() throws Exception {

client.set("k1",3600,"Hello happy");

client.touch("k1",10);

}

演示命名空间

因为memcached中没有数据表的概念，XMemcached引入了命名空间的概念，可以对数据进行分块存储，而实际底层操作则是变相的修改key的名称来实现的。

public static void showNameSpace() throwsException {

String ns1= "ns1";

String ns2= "ns2";//赋值操作

client.withNamespace(ns1, new MemcachedClientCallable() {public String call(MemcachedClient memcachedClient) throwsMemcachedException, InterruptedException, TimeoutException {

memcachedClient.set("k10",0," Hello chenz!! ");return null;

}

});

String str= client.get("k10");

System.out.println("str="+str);

String k10= client.withNamespace(ns1, new MemcachedClientCallable() {public String call(MemcachedClient memcachedClient) throwsMemcachedException, InterruptedException, TimeoutException {return memcachedClient.get("k10");

}

});

System.out.println("k10="+k10);

String k102= client.withNamespace(ns2, new MemcachedClientCallable() {public String call(MemcachedClient memcachedClient) throwsMemcachedException, InterruptedException, TimeoutException {return memcachedClient.get("k10");

}

});

System.out.println("k102="+k102);

}

测试结果：

我们通过查询以下memcached中的所有key

可以看到前面三个是系统为我们创建并和namespace相关的，我们查询一下namespace:ns1的value值，即可看出其中端倪：