使用实例
3.1介绍
目前支持所有的memcached 文本协议(二进协议正在开发中，预计在1.2中会出现) ，现包括了 get/gets、set、add、replace、delete、append、prepend、cas、multi get/gets、incr、decr、version、stats、flush_all等。
3.2 简单实例
MemcachedClient client;
try {
client = new XMemcachedClient("localhost",11211);//默认端口
// store a value for one hour(synchronously).
String someObject = "缓存这个一个小时可以吗？";
client.set("key", 3600, someObject);
// Retrieve a value.(synchronously).
Object getSomeObject = client.get("key");
// delete
client.delete("key");
System.out.println(getSomeObject.toString());
} catch (TimeoutException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (MemcachedException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
以上代码是没有经过Spring管理的，XMemcachedClient是一个常驻程序。所以可以考虑将它置入到Spring中，配置方式前面已讲过。
private MemcachedClient memcachedClient;
public void setMemcachedClient(MemcachedClient memcachedClient) {
this.memcachedClient = memcachedClient;
注入后直接可使用。3.3 监听服务器映射
Xmemcached源代码中XMemcachedClientMBean的setServerWeight(String server, int weight)方法可以将被监听服务器进行编号。具体使用方式可以用：
MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:12000 localhost:12001"),new int[]{1,3}); //编号为1,3
MemcachedClient memcachedClient=builder.build();
3.4动态改变被监听服务器
Xmemcached支持动态的增加或者删除监听服务器，方式如下：
MemcachedClient client=new XMemcachedClient(AddrUtil.getAddresses("server1:11211 server2:11211"));
//Add two new memcached nodes
client.addServer("server3:11211 server4:11211");
//Remove memcached servers
client.removeServer("server1:11211 server2:11211");
3.5 使用CAS更新缓存
CASOperation需要先gets获取cas值，然后再调用cas方法更新，XMemcached提供了一个包装类可以帮你搞定这两步。以下是一个使用实例：
class CASThread extends Thread {
static final class IncrmentOperation implements CASOperation<Integer> {
*Max repeat times.if repeat times is great than this value,
*xmemcached will throw a TimeoutException.
@Override
public int getMaxTries() {
return Integer.MAX_VALUE;
}
//increase current value
@Override
public Integer getNewValue(long currentCAS, Integer currentValue) {
return currentValue + 1; // 当前值+1
}
private XMemcachedClient mc;
private CountDownLatch cd;
public CASThread(XMemcachedClient mc, CountDownLatch cdl) {
super();
this.mc = mc;
this.cd = cdl;
}
public void run() {
try {
//do the cas operation
if (mc.cas("a", 0, new IncrmentOperation()))
this.cd.countDown();
} catch (Exception e) {
e.printStackTrace();
}
}
public class CASTest {
public static void main(String[] args) throws Exception {
if (args.length < 2) {
System.err.println("Usage:java CASTest [threadNum] [server]");
System.exit(1);
//threads num
int NUM = Integer.parseInt(args[0]);
XMemcachedClient mc = new XMemcachedClient(AddrUtil.getAddresses(args[1]));
//initial value is 0
mc.set("a", 0, 0);
CountDownLatch cdl = new CountDownLatch(NUM);
long start = System.currentTimeMillis();
//start NUM threads to increment the value
for (int i = 0; i < NUM; i++)
new CASThread(mc, cdl).start();
cdl.await();
System.out.println("test cas,timed:"
+ (System.currentTimeMillis() - start));
System.out.println("result=" + mc.get("a"));
mc.shutdown();
}