Java中使用Closeable接口自動關(guān)閉資源詳解

更新時間：2023年12月02日 08:34:47 作者：nuomizhende45

這篇文章主要介紹了Java中使用Closeable接口自動關(guān)閉資源詳解,Closeable接口繼承于AutoCloseable,主要的作用就是自動的關(guān)閉資源,其中close()方法是關(guān)閉流并且釋放與其相關(guān)的任何方法,如果流已被關(guān)閉,那么調(diào)用此方法沒有效果,需要的朋友可以參考下

Closeable接口自動關(guān)閉資源

Closeable接口繼承于AutoCloseable，主要的作用就是自動的關(guān)閉資源，其中close()方法是關(guān)閉流并且釋放與其相關(guān)的任何方法，如果流已被關(guān)閉，那么調(diào)用此方法沒有效果，像 InputStream和OutputStream類都實現(xiàn)了該接口，源碼如下

/*
 * 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，我們通過try{} finally{} 在finally中釋放資源。

2.對于實現(xiàn)AutoCloseable接口的類的實例，將其放到try后面（我們稱之為：帶資源的try語句），在try結(jié)束的時候，會自動將這些資源關(guān)閉（調(diào)用close方法）。

test1方法是最常規(guī)的try{}catch{}finally{}

test2是使用closeable自動釋放資源

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 處理邏輯");
        } catch (Exception e) {
            System.out.println("test1方法 異常處理");
        } finally {
            System.out.println("test1方法 釋放資源");
        }
    }
    public static void test2() {
        try (CloseableTest c = new CloseableTest()) {
            System.out.println("test2方法 處理邏輯");
        } catch (Exception e) {
            System.out.println("test2方法 處理異常");
        }
    }
    @Override
    public void close() throws IOException {
        System.out.println("test2方法這里自動釋放資源");
    }
    public static void main(String[] args) {
        test1();
        test2();
    }
}

運行結(jié)果如下