Memcached的incr 和 decr命令用于增加现有键的数值递减。如果键未找到或如果关键的不是数字,则返回NOT_FOUND。那么CLIENT_ERROR不能增加或返回递减非数值错误。
memcached的incr命令的基本语法如下所示:
incr key increment_value
set visitors 0 900 2 10 STORED get visitors VALUE visitors 0 2 10 END incr visitors 5 15 get visitors VALUE visitors 0 2 15 END
在上面的例子中,我们已经使用visitors为一个键,并设置10为初始值,之后为visitors增量5。
memcached的decr命令的基本语法如下所示:
decr key decrement_value
set visitors 0 900 2 10 STORED get visitors VALUE visitors 0 2 10 END decr visitors 5 5 get visitors VALUE visitors 0 1 5 END
要在memcached服务器增加,减小数据,需要使用memcached的incr, decr方法。
import net.spy.memcached.MemcachedClient; public class MemcachedJava { public static void main(String[] args) { //Connecting to Memcached server on localhost MemcachedClient mcc = new MemcachedClient(new InetSocketAddress("127.0.0.1", 11211)); System.out.println("Connection to server sucessfully"); System.out.println("set status:"+mcc.set("count", 900, "5").isDone()); //Get value from cache System.out.println("Get from Cache:"+mcc.get("count")); // now increase the stored value System.out.println("Increment value:"+mcc.incr("count", 2)); // now decrease the stored value System.out.println("Decrement value:"+mcc.decr("count", 1)); // now get the final stored value System.out.println("Get from Cache:"+mcc.get("count")); } }
当上述程序编译和运行,它提供了以下的输出:
Connection to server successfully set status:true Get from Cache:5 Increment value:7 Decrement value:6 Get from Cache:6