Memcached - 删除键

17 Mar 2025 | 阅读 2 分钟

Memcached 的 delete 命令用于从 Memcached 服务器删除现有的键。这意味着如果缓存中存在该项，则将其删除。

语法

此处，

key: 这是存储在 Memcached 中并从中检索的数据键。

noreply: 这是一个可选参数。它用于通知服务器不发送任何回复。

返回值

此命令将返回以下值

DELETED: 表示成功删除。

ERROR: 表示删除数据时出错或语法错误。

NOT_FOUND: 表示键在 Memcached 服务器中不存在。

Ubuntu 中的示例

让我们看一个删除命令的例子。这里我们将使用 'city' 作为键，并将 'bangalore' 存储在其中，过期时间为 900 秒。之后，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

假设 Memcached 服务器在主机 127.0.0.1 和端口 11211 上运行。在这里，我们将使用 delete() 方法从 Memcached 服务器删除数据。

示例 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

示例 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("javatpoint", 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("javatpoint value in cache - " + mcc.get("javatpoint"));

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

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

         // retrieve and check the value from cache
         System.out.println("javatpoint 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
javatpoint value in cache - largest online tutorials library
delete status:true
javatpoint value in cache - null

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