当我关闭BufferedInputStream时，底层的InputStream是否也关闭了？ [重复]

Question

这个问题在这里已有答案：

• Closing inputstreams in Java 6个答案

InputStream in = SomeClass.getInputStream(...);
BufferedInputStream bis = new BufferedInputStream(in);

try {
    // read data from bis
} finally {
    bis.close();
    in.close();    
}

BufferedInputStream.close()的javadoc未提及底层流是否已关闭：

关闭此输入流并释放与该流关联的所有系统资源。关闭流后，进一步的read（），available（），reset（）或skip（）调用将抛出IOException。关闭先前关闭的流无效。

是否必须明确调用in.close()，还是应该通过调用bis.close()来关闭它？

Answer 1

来自BufferedInputStream的源代码：

public void close() throws IOException {
    byte[] buffer;
    while ( (buffer = buf) != null) {
        if (bufUpdater.compareAndSet(this, buffer, null)) {
            InputStream input = in;
            in = null;
            if (input != null)
                input.close();
            return;
        }
        // Else retry in case a new buf was CASed in fill()
    }
}

所以答案是：是的

Answer 2

BufferedInputStream本身不包含任何系统资源;它只是包含一个保存这些资源的InputStream。因此，BufferedInputStream将关闭操作转发到包装的InputStream，然后将释放其资源。

Answer 3

当您关闭BufferedInputStream时，基础InputStream确实也已关闭。 :)

Answer 4

是。底层流将被关闭。

Answer 5

这是Java实现

/**
 * Closes this input stream and releases any system resources
 * associated with the stream.
 * Once the stream has been closed, further read(), available(), reset(),
 * or skip() invocations will throw an IOException.
 * Closing a previously closed stream has no effect.
 *
 * @exception  IOException  if an I/O error occurs.
 */
public void close() throws IOException {
    byte[] buffer;
    while ( (buffer = buf) != null) {
        if (bufUpdater.compareAndSet(this, buffer, null)) {
            InputStream input = in;
            in = null;
            if (input != null)
                input.close();
            return;
        }
        // Else retry in case a new buf was CASed in fill()
    }
}

因此，流将被关闭