guava快速入门（三）

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;

public class LoadingCacheDemo {

	public static void main(String[] args) {
		LoadingCache<String, String> cache = CacheBuilder.newBuilder().maximumSize(100) // 最大缓存数目
				.expireAfterAccess(2, TimeUnit.SECONDS) // 缓存1秒后过期
				.build(new CacheLoader<String, String>() {
					@Override
					public String load(String key) throws Exception {
						return key;
					}
				});
		cache.put("j", "java");
		cache.put("c", "cpp");
		cache.put("s", "scala");
		cache.put("g", "go");
		try {
			System.out.println(cache.get("j"));
			TimeUnit.SECONDS.sleep(1);
			System.out.println(cache.get("s")); // 1秒后 输出scala
			TimeUnit.SECONDS.sleep(2);
			System.out.println(cache.get("s")); // 2秒后 输出s


		} catch (ExecutionException | InterruptedException e) {
			e.printStackTrace();
		}
	}

}

java
scala
s

import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

public class CallbackDemo {

	public static void main(String[] args) {
		Cache<String, String> cache = CacheBuilder.newBuilder().maximumSize(100)
				.expireAfterAccess(1, TimeUnit.SECONDS)
				.build();
		try {
			String result = cache.get("java", () -> "hello java");
			System.out.println(result);
		} catch (ExecutionException e) {
			e.printStackTrace();
		}
	}

}

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;

import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;

public class ListenableFutureDemo {

	public static void main(String[] args) {
		// 将ExecutorService装饰成ListeningExecutorService
		ListeningExecutorService service = MoreExecutors.
				listeningDecorator(Executors.newCachedThreadPool());

		// 通过异步的方式计算返回结果
		ListenableFuture<String> future = service.submit(() -> {
			System.out.println("call execute..");
			return "task success!";
		});

		// 有两种方法可以执行此Future并执行Future完成之后的回调函数
		future.addListener(() -> { // 该方法会在多线程运算完的时候,指定的Runnable参数传入的对象会被指定的Executor执行
			try {
				System.out.println("result: " + future.get());
			} catch (InterruptedException | ExecutionException e) {
				e.printStackTrace();
			}
		}, service);

		Futures.addCallback(future, new FutureCallback<String>() {
			@Override
			public void onSuccess( String result) {
				System.out.println("callback result: " + result);
			}

			@Override
			public void onFailure(Throwable t) {
				System.out.println(t.getMessage());
			}
		}, service);
	}

}

call execute..
result: task success!
callback result: task success!

import java.io.File;
import java.io.IOException;
import java.util.List;

import com.google.common.base.Charsets;
import com.google.common.collect.ImmutableList;
import com.google.common.io.Files;

public class FileDemo {

	public static void main(String[] args) {
		File file = new File(System.getProperty("user.dir"));
		System.out.println(file.getName());
		System.out.println(file.getPath());
	}

	// 写文件
	private void writeFile(String content, File file) throws IOException {
		if (!file.exists()) {
			file.createNewFile();
		}
		Files.write(content.getBytes(Charsets.UTF_8), file);
	}

	// 读文件
	private List<String> readFile(File file) throws IOException {
		if (!file.exists()) {
			return ImmutableList.of(); // 避免返回null
		}
		return Files.readLines(file, Charsets.UTF_8);
	}

	// 文件复制
	private void copyFile(File from, File to) throws IOException {
		if (!from.exists()) {
			return;
		}
		if (!to.exists()) {
			to.createNewFile();
		}
		Files.copy(from, to);
	}

}

collection-others
D:\GITHUB\java\code\test01\collection-others