Closeable接口优雅方便的自动关闭资源

Dear 丶 2023-02-20 05:58 97阅读 0赞

转载自：[https://blog.csdn.net/nuomizhende45/article/details/105924637][https_blog.csdn.net_nuomizhende45_article_details_105924637]

## 叙述 ##

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

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L251b21pemhlbmRlNDU_size_16_color_FFFFFF_t_70][]

[https_blog.csdn.net_nuomizhende45_article_details_105924637]: https://blog.csdn.net/nuomizhende45/article/details/105924637
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L251b21pemhlbmRlNDU_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200505111318732.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L251b21pemhlbmRlNDU=,size_16,color_FFFFFF,t_70