package guavacache;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.TimeUnit;

import com.google.common.cache.CacheBuilder;

import com.google.common.cache.CacheLoader;

import com.google.common.cache.LoadingCache;

import com.google.common.cache.RemovalListener;

import com.google.common.cache.RemovalNotification;

public class cachetest {

	public static class Student {

		private int id;

		public String name;

		public int getId() {

			return id;

		}

		public void setId(int id) {

			this.id = id;

		}

		public String getName() {

			return name;

		}

		public void setName(String name) {

			this.name = name;

		}

		@Override

		public String toString() {

			return id + "| " + name;

		}

	}

	public static void main(String[] args) throws ExecutionException, InterruptedException {

		// 缓存接口这里是LoadingCache，LoadingCache在缓存项不存在时可以自动加载缓存

		LoadingCache<Integer, Student> studentCache

		// CacheBuilder的构造函数是私有的，只能通过其静态方法newBuilder()来获得CacheBuilder的实例

				= CacheBuilder.newBuilder()

						// 设置并发级别为8，并发级别是指可以同时写缓存的线程数

						.concurrencyLevel(8)

						// 设置写缓存后8秒钟过期

						.expireAfterWrite(18, TimeUnit.SECONDS)

						// 设置缓存容器的初始容量为10

						.initialCapacity(2)

						// 设置缓存最大容量为100，超过100之后就会按照LRU最近虽少使用算法来移除缓存项

						.maximumSize(2)

						// 设置要统计缓存的命中率

						.recordStats()

						// 设置缓存的移除通知

						.removalListener(new RemovalListener<Object, Object>() {

							public void onRemoval(RemovalNotification<Object, Object> notification) {

								System.out.println(

										notification.getKey() + " was removed, cause is " + notification.getCause());

							}

						})

						// build方法中可以指定CacheLoader，在缓存不存在时通过CacheLoader的实现自动加载缓存

						.build(new CacheLoader<Integer, Student>() {

							@Override

							public Student load(Integer key) throws Exception {

								System.out.println("load student " + key);

								Student student = new Student();

								student.setId(key);

								student.setName("name " + key);

								return student;

							}

						});

//		for (int i = 0; i < 20; i++) {

//			// 从缓存中得到数据，由于我们没有设置过缓存，所以需要通过CacheLoader加载缓存数据

//			Student student = studentCache.get(i);

//			System.out.println(student);

//			// 休眠1秒

//			TimeUnit.SECONDS.sleep(1);

//		}

		System.out.println("cache stats:");

		// 最后打印缓存的命中率等 情况

		System.out.println(studentCache.stats().toString());

	}

}

		Student student = studentCache.get(1);

		System.out.println(student);

		student = studentCache.get(1);

		System.out.println(student);

		student = studentCache.get(1);

		System.out.println(student);

		student = studentCache.get(2);

		System.out.println(student);

		student = studentCache.get(3);

		System.out.println(student);

    <dependency>

    	<groupId>com.google.guava</groupId>

    	<artifactId>guava</artifactId>

    	<version>18.0</version>

	</dependency>