Java 7 个压缩文件

Question

我有一段使用deflate算法压缩文件的代码：

public static File compressOld(File rawFile) throws IOException
{
    File compressed = new File(rawFile.getCanonicalPath().split("\.")[0]
            + "_compressed." + rawFile.getName().split("\.")[1]);

    InputStream inputStream = new FileInputStream(rawFile);
    OutputStream compressedWriter = new DeflaterOutputStream(new FileOutputStream(compressed));
    byte[] buffer = new byte[1000];
    int length;

    while ((length = inputStream.read(buffer)) > 0)
    {
        compressedWriter.write(buffer, 0, length);
    }

    inputStream.close();
    compressedWriter.close();

    return compressed;
}

但是，我对OutputStream copying loop since it's the "outdated" way of writing to streams. Instead, I want to use a Java 7 API method such as Files.copy不满意：

public static File compressNew(File rawFile) throws IOException
{
    File compressed = new File(rawFile.getCanonicalPath().split("\.")[0]
            + "_compressed." + rawFile.getName().split("\.")[1]);

    OutputStream compressedWriter = new DeflaterOutputStream(new FileOutputStream(compressed));
    Files.copy(compressed.toPath(), compressedWriter);

    compressedWriter.close();

    return compressed;
}

但是后一种方法不能正常工作，压缩文件乱七八糟，只复制了几个字节。怎么会？

Answer 1

我主要看到两个问题

您从目标而不是源复制。我认为复制必须更改为 Files.copy(rawFile.toPath(), compressedWriter);.
copy 的 Java 文档说： "Note that if the given output stream is Flushable then its flush method may need to invoked after this method completes so as to flush any buffered output." 所以，你必须在 [=11] 之后调用 OutputStream 的 flush 方法=].

另外还有一点。 Java副本的文档说：

It is strongly recommended that the output stream be promptly closed if an I/O error occurs.

您可以关闭 finally 块中的 OutputStream 以确保它在出现错误时发生。另一种可能性是使用 Java 7.

中引入的 try with resources

Java 7 个压缩文件

Java 7 Deflating Files

java

deflate

java-7