Java中使用Closeable接口自动关闭资源详解
作者:nuomizhende45
这篇文章主要介绍了Java中使用Closeable接口自动关闭资源详解,Closeable接口继承于AutoCloseable,主要的作用就是自动的关闭资源,其中close()方法是关闭流并且释放与其相关的任何方法,如果流已被关闭,那么调用此方法没有效果,需要的朋友可以参考下
Closeable接口自动关闭资源
Closeable接口继承于AutoCloseable,主要的作用就是自动的关闭资源,其中close()方法是关闭流并且释放与其相关的任何方法,如果流已被关闭,那么调用此方法没有效果,像 InputStream和OutputStream类都实现了该接口,源码如下
/* * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.io; import java.io.IOException; /** * A {@code Closeable} is a source or destination of data that can be closed. * The close method is invoked to release resources that the object is * holding (such as open files). * * @since 1.5 */ public interface Closeable extends AutoCloseable { /** * Closes this stream and releases any system resources associated * with it. If the stream is already closed then invoking this * method has no effect. * * <p> As noted in {@link AutoCloseable#close()}, cases where the * close may fail require careful attention. It is strongly advised * to relinquish the underlying resources and to internally * <em>mark</em> the {@code Closeable} as closed, prior to throwing * the {@code IOException}. * * @throws IOException if an I/O error occurs */ public void close() throws IOException; }
Closeable用法
1.在1.7之前,我们通过try{} finally{} 在finally中释放资源。
2.对于实现AutoCloseable接口的类的实例,将其放到try后面(我们称之为:带资源的try语句),在try结束的时候,会自动将这些资源关闭(调用close方法)。
test1方法是最常规的try{}catch{}finally{}
test2是使用closeable自动释放资源
package com.canal.demo; import java.io.Closeable; import java.io.IOException; public class CloseableTest implements Closeable { public static void test1() { try { System.out.println("test1方法 处理逻辑"); } catch (Exception e) { System.out.println("test1方法 异常处理"); } finally { System.out.println("test1方法 释放资源"); } } public static void test2() { try (CloseableTest c = new CloseableTest()) { System.out.println("test2方法 处理逻辑"); } catch (Exception e) { System.out.println("test2方法 处理异常"); } } @Override public void close() throws IOException { System.out.println("test2方法这里自动释放资源"); } public static void main(String[] args) { test1(); test2(); } }
运行结果如下
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