Memcached-删除key

本文概述

• Ubuntu中的示例
• Windows中的示例
• 使用Java应用程序删除数据

Memcached delete命令用于从Memcached服务器删除现有密钥。这意味着它将从缓存中删除一个项目(如果存在)。

句法

delete key [noreply]

这里,

key：它是从Memcached存储和检索的密钥数据。

noreply：这是一个可选参数。它用于通知服务器不发送任何答复。

返回值

此命令将返回以下值：

删除：表示删除成功。

错误：删除数据或语法错误时显示错误。

NOT_FOUND：表明该密钥在Memcached服务器中不存在。

Ubuntu中的示例

让我们看一下delete命令的示例。在这里, 我们将使用”城市”作为关键字, 并在900秒的时间到期后将”班加罗尔”存储在其中。此后, 使用delete命令删除键” city”。

set city 0 900 9
bangalore
STORED
get city
VALUE city 0 9
bangalore
END
delete city
DELETED
get city
END
delete city
NOT_FOUND

Windows中的示例

set city 0 900 9
bangalore
STORED
get city
VALUE city 0 9
bangalore
END
delete city
DELETED
get city
END
delete city
NOT_FOUND

Memcached服务器：

Memcached客户端：

使用Java应用程序删除数据

让我们考虑一下Memcached服务器正在主机127.0.0.1和端口11211上运行。在这里, 我们将使用delete()方法从Memcached服务器中删除数据。

例子1

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 successful");
      System.out.println("set status:"+mcc.set("city", 900, "bangalore").done);
      
      // Get value from cache
      System.out.println("Get from Cache:"+mcc.get("city"));
      
      // delete value from cache
      System.out.println("Delete from Cache:"+mcc.delete("city").isDone());
      
      // check whether value exists or not
      System.out.println("Get from Cache:"+mcc.get("city"));
   }
}

输出

Connection to server successful
set status: true
Get from Cache: Bangalore
Delete from Cache: true
Get from Cache: null

例子2

import java.net.InetSocketAddress;
import java.util.concurrent.Future;

import net.spy.memcached.MemcachedClient;

public class MemcachedJava {
   public static void main(String[] args) {
   
      try{
   
         // Connecting to Memcached server on localhost
         MemcachedClient mcc = new MemcachedClient(new InetSocketAddress("127.0.0.1", 11211));
         System.out.println("Connection to server sucessful.");

         // add data to memcached server
         Future fo = mcc.set("srcmini", 900, "largest online tutorials library");

         // print status of set method
         System.out.println("set status:" + fo.get());

         // retrieve and check the value from cache
         System.out.println("srcmini value in cache - " + mcc.get("srcmini"));

         // try to delete data with existing key
         Future fo = mcc.delete("srcmini");

         // print status of delete method
         System.out.println("delete status:" + fo.get());

         // retrieve and check the value from cache
         System.out.println("srcmini value in cache - " + mcc.get("codingground"));

         // Shutdowns the memcached client
         mcc.shutdown();
         
      }catch(Exception ex)
         System.out.println(ex.getMessage());
   }
}

输出

Connection to server successful
set status:true
srcmini value in cache - largest online tutorials library
delete status:true
srcmini value in cache - null