guava cache

    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(8, TimeUnit.SECONDS)
　　　　　　　　　　//设置写缓存后1秒钟刷新
　　　　　　　　　.refreshAfterWrite(1, TimeUnit. SECONDS)
                //设置缓存容器的初始容量为10
                .initialCapacity(10)
                //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(100)
                //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>() {
                    @Override
                    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(1);
            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());
    }

public class CacheModel {
    public Student getStudent(Integer key){
        System.out.println("load student " + key);
        Student student = new Student();
        student.setId(key);
        student.setName("name " + key);
        return student;
    }
    //load Method
    public void loadCacheA() throws Exception{
         LoadingCache<Integer,Student> studentCache= CacheBuilder.newBuilder().concurrencyLevel(8).
                 expireAfterWrite(8, TimeUnit.SECONDS).refreshAfterWrite(1, TimeUnit. SECONDS).initialCapacity(10).maximumSize(100)
                 .recordStats().removalListener(new RemovalListener<Object, Object>() {
                     public void onRemoval(RemovalNotification<Object, Object> notification) {
                                 System.out.println(notification.getKey() + " was removed, cause is " + notification);}
                     }).build(
                    new CacheLoader<Integer, Student>() {
                        @Override
                        public Student load(Integer key) throws Exception {
                            return getStudent(key);
                           }
                        }
          );

         for (int i=0;i<20;i++) {
           Student student = studentCache.get(1);
           System.out.println(student);
           TimeUnit.SECONDS.sleep(1);
         }

         System.out.println("cache stats:");
         System.out.println(studentCache.stats().toString());
         
    }
    //call back Method
    public void loadCacheB(final Integer key) throws Exception{
         Cache<Integer, Student> cache = CacheBuilder.newBuilder().maximumSize(1000).build();  
                 Student resultVal = cache.get(key, new Callable<Student>() {  
                 public Student call() {  
                    return getStudent(key);
                }  
            });   
             for (int i=0;i<20;i++) {
                System.out.println(resultVal);
                TimeUnit.SECONDS.sleep(1);
              }

              System.out.println("cache stats:");
              System.out.println(cache.stats().toString());
    }
    
    public static void main(String[] args) throws Exception {
        CacheModel cache = new CacheModel();
        cache.loadCacheB(2);
    }