Java BufferedWriter和OutputStream .close（）方法

Question

我是java的新手，有一個關於BufferedWriter和OutputStream關閉的問題。

我有一些邏輯，使用try-with-resources很不方便：

public static void writeFile(String fileName, String encoding, String payload) {

    BufferedWriter writer = null;
    OutputStream stream = null;

    try {
        boolean needGzip = payload.getBytes(encoding).length > gzipZize;

        File output = needGzip ? new File(fileName + ".gz") : new File(fileName);
        stream = needGzip ? new GZIPOutputStream(new FileOutputStream(output)) : new FileOutputStream(output);

        writer = new BufferedWriter(new OutputStreamWriter(stream, encoding));
        writer.write(payload);

    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            writer.close();
            stream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

所以，我必須自己關閉所有資源。 我應該關閉OutputStream和BufferedWriter嗎？ 或者可以關閉BufferedWriter？

我的代碼一切正常嗎？

Answer 1

可以關閉BufferedWriter. 如果您遵循Javadoc，您將看到它關閉所有嵌套流。

Answer 2

如果關閉BufferedWriter，它的流也將被關閉，但BufferedWriter和OutputStream都實現了Closeable。 因此，如果您想要，您可以使用try with resource來處理關閉

例如 ：

public static void writeFile(String fileName, String encoding, String payload) {
    File output = new File(fileName);
    try (OutputStream stream = new FileOutputStream(output);
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(stream, encoding))) {
        writer.write(payload);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

編輯：添加getStream以檢查是否需要gzip流或否

注意：這個答案只是代碼的“更新”，我不確定你一般要做什么，所以它可能不是你程序的最佳解決方案

public static void writeFile(String fileName, String encoding, String payload) {
    try (BufferedWriter writer = new BufferedWriter(
            new OutputStreamWriter(getStream(fileName, encoding, payload), encoding))) {
        writer.write(payload);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public static OutputStream getStream(String fileName, String encoding, String payload) throws IOException {
    boolean needGzip = payload.getBytes(encoding).length > gzipZize;
    File output = needGzip ? new File(fileName + ".gz") : new File(fileName);
    return needGzip ? new GZIPOutputStream(new FileOutputStream(output)) : new FileOutputStream(output);
}

Answer 3

不，把它留給Java，讓它來處理它：

public static void writeFile(String fileName, String encoding,
            String payload) {
        boolean needGzip = payload.getBytes(Charset.forName(encoding)).length > gzipZize;
        File output = needGzip ? new File(fileName + ".gz")
                : new File(fileName);
        try (OutputStream stream = needGzip ? new GZIPOutputStream(
                new FileOutputStream(output)) : new FileOutputStream(output);
                BufferedWriter writer = new BufferedWriter(
                        new OutputStreamWriter(stream, encoding))) {
            writer.write(payload);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }