java - 尝试内和尝试后返回位置时的不同行为

Question

我有以下两个代码块，我用它们来压缩字符串。

代码1

public static String compressResponse(String response) throws IOException {

    Deflater deflater = new Deflater(Deflater.DEFLATED, true);
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    DeflaterOutputStream deflaterOutputStream = new DeflaterOutputStream(byteArrayOutputStream, deflater);
    try {
        deflaterOutputStream.write(response.getBytes(StandardCharsets.UTF_8));
        return Base64.encodeBytes(byteArrayOutputStream.toByteArray(), Base64.DONT_BREAK_LINES);
    } finally {
        deflaterOutputStream.close();
    }
}

代码2

 public static String compressResponse(String response) throws IOException {

    Deflater deflater = new Deflater(Deflater.DEFLATED, true);
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    DeflaterOutputStream deflaterOutputStream = new DeflaterOutputStream(byteArrayOutputStream, deflater);
    try {
        deflaterOutputStream.write(response.getBytes(StandardCharsets.UTF_8));
    } finally {
        deflaterOutputStream.close();
    }
    return Base64.encodeBytes(byteArrayOutputStream.toByteArray(), Base64.DONT_BREAK_LINES);
}

只有第二种方法可以正常工作，而第一种方法始终返回空字符串。我理解这种不同的行为是由于返回 block 相对于finally block 的不同放置而发生的。其具体行为是什么？

Answer 1

在第二个示例中，byteArrayOutputStream 被填充，因为 deflaterOutputStream 已关闭并刷新。