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
<dependency>
<groupId>com.googlecode.xmemcached</groupId>
<artifactId>xmemcached</artifactId>
<version>2.4.0</version>
</dependency>
二、创建Java文件
UserModel.java
package com.czhappy.memcached_project.vo;
import java.io.Serializable;
public class UserModel implements Serializable{
private int uuid;
private String userName;
private int age;
public UserModel(){}
public UserModel(int uuid, String userName, int age) {
this.uuid = uuid;
this.userName = userName;
this.age = age;
}
public int getUuid() {
return uuid;
}
public void setUuid(int uuid) {
this.uuid = uuid;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "UserModel{" +
"uuid=" + uuid +
", userName='" + userName + '\'' +
", age=" + age +
'}';
}
}
ConnectonHelper.java
package com.czhappy.memcached_project.utils;
import net.rubyeye.xmemcached.MemcachedClient;
import net.rubyeye.xmemcached.MemcachedClientBuilder;
import net.rubyeye.xmemcached.XMemcachedClient;
import net.rubyeye.xmemcached.XMemcachedClientBuilder;
import net.rubyeye.xmemcached.utils.AddrUtil;
import org.junit.Test;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.Map;
public class ConnectonHelper {
public static MemcachedClient 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();
}
return memcachedClient;
}
public static void main(String[] args) throws Exception {
// 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)throws Exception{
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) throws Exception {
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) throws Exception{
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)throws Exception{
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)throws Exception{
String key = "set-user:" + um.getUuid();
// 第一件事先获取版本号
GetsResponse<UserModel> 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() throws Exception {
// 操作XMemcached提供的CAS操作
client.cas("k1", new CASOperation<String>() {
// 重试次数
public int getMaxTries() {
return Integer.MAX_VALUE;
}
// 修改内容
public String getNewValue(long cas, String currentValue) {
return "Hi ! "+currentValue + "！！！！！";
}
});
}
- 定义数值操作【incr/decr】方法
public static void showNumChange()throws Exception{
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() throws Exception{
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() throws Exception {
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() throws Exception {
String ns1 = "ns1";
String ns2 = "ns2";
// 赋值操作
client.withNamespace(ns1, new MemcachedClientCallable<String>() {
public String call(MemcachedClient memcachedClient) throws MemcachedException, 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<String>() {
public String call(MemcachedClient memcachedClient) throws MemcachedException, InterruptedException, TimeoutException {
return memcachedClient.get("k10");
}
});
System.out.println("k10="+k10);
String k102 = client.withNamespace(ns2, new MemcachedClientCallable<String>() {
public String call(MemcachedClient memcachedClient) throws MemcachedException, 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：
