Google Guava Cache 示列

绝地灬酷狼 2022-07-16 06:45 214阅读 0赞

### google guava cache ###

##### 引用maven依赖 #####

<dependency>
        <groupId>com.google.guava</groupId>
        <artifactId>guava</artifactId>
        <version>18.0</version>
    </dependency>

##### java代码 #####

import com.google.common.cache.CacheBuilder;
    import com.google.common.cache.CacheLoader;
    import com.google.common.cache.LoadingCache;
    
    import java.util.concurrent.ExecutionException;
    import java.util.concurrent.TimeUnit;
    
    /** * Created by zhengyong on 16/10/9. */
    public class GuavaCacheTest { 
    
        private static LoadingCache<String, String> graphs = null;
    
        public static void main(String[] args) {
            loadDataToCache();
            // 第一次从数据源获取,并缓存
            String value1 = getValue("mykey");
            // 第二次从缓存获取
            String value2 = getValue("mykey");
            // 过期重新从数据源加载进缓存
            try {
                Thread.sleep(10);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            String value3 = getValue("mykey");
            String value4 = getValue("mykey");
            String value5 = getValue("mykey2");
            String value6 = getValue("mykey2");
        }
    
        /** * 根据key获取值 * * @param key 查询条件key * @return 返回value值 */
        private static String getValue(String key) {
            String resultVal = null;
            try {
                resultVal = graphs.get(key);
            } catch (ExecutionException e) {
                e.printStackTrace();
            }
            System.out.println(String.format("get key=%s return value=%s", key, resultVal));
            return resultVal;
        }
    
        /** * 声明加载数据源方式 */
        private static void loadDataToCache() {
    
            graphs = CacheBuilder.newBuilder().maximumSize(1000).expireAfterWrite(10, TimeUnit.MILLISECONDS).build(new CacheLoader<String, String>() {
    
              public String load(String key) {
                  // 这里是key根据实际去取值的方法
                  System.out.println(String.format("load '%s' from database...",
                                                   key));
                  return "value_" + key;
              }
          });
        }
    }

##### 运行结果 #####

load 'mykey' from database... get key=mykey return value=value_mykey get key=mykey return value=value_mykey load 'mykey' from database... get key=mykey return value=value_mykey get key=mykey return value=value_mykey load 'mykey2' from database... get key=mykey2 return value=value_mykey2 get key=mykey2 return value=value_mykey2