使用Google Guava实现定时缓存功能

喜欢ヅ旅行 2022-08-20 10:16 424阅读 0赞

一：加入maven依赖

<dependency>
    	<groupId>com.google.guava</groupId>
    	<artifactId>guava</artifactId>
    	<version>19.0</version>
    </dependency>

二：使用缓存

方法一：

package com.test.guava;
    
    import java.util.concurrent.TimeUnit;
    
    import com.google.common.cache.Cache;
    import com.google.common.cache.CacheBuilder;
    
    public class UserService
    {
    	private final Cache<String, String> cache;
    	
    	public UserService()
    	{
    		/**
    		 * 5秒自动过期
    		 */
    		cache = CacheBuilder.newBuilder().expireAfterWrite(5, TimeUnit.SECONDS).build();
    	}
    	
    	public String getUserName(String id) throws Exception
    	{
    		return cache.get(id, () -> {
    			System.out.println("method invoke2");
    			//这里执行查询数据库，等其他复杂的逻辑
    			return "User:" + id;
    		});
    	}
    }

方法二：

package com.test.guava;
    
    import java.util.concurrent.TimeUnit;
    
    import com.google.common.cache.CacheBuilder;
    import com.google.common.cache.CacheLoader;
    import com.google.common.cache.LoadingCache;
    
    public class UserService
    {
    	private final LoadingCache<String, String> cache;
    	
    	public UserService()
    	{
    		/**
    		 * 5秒自动过期
    		 */
    		cache = CacheBuilder.newBuilder().expireAfterWrite(5, TimeUnit.SECONDS).build(new CacheLoader<String, String>() {
        		public String load(String id) throws Exception
        		{
        			System.out.println("method inovke");
        			//这里执行查询数据库，等其他复杂的逻辑
        	        return "User:" + id;
        		}
        	});
    	}
    	
    	public String getUserName(String id) throws Exception
    	{
    		return cache.get(id);
    	}
    }

三：测试代码：

package com.test.guava;
    
    import java.util.concurrent.TimeUnit;
    
    public class GuavaCacheTest
    {
    	public static void main(String[] args)throws Exception
    	{
    		UserService us = new UserService();
    		for(int i=0;i<20;i++)
    		{
    			System.out.println(us.getUserName("1001"));
    			TimeUnit.SECONDS.sleep(1);
    		}
    	}
    }

执行测试代码，输出如下：

![Center][]

[Center]: /images/20220731/40ae7ef4f21444d5b2b53285efd140f1.png