java 将二进制文件读入字符串
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Reading a binary file into a string
提问by Sandor
It must be obvious, but I can't figure it out. I spent almost a whole day for this. I'll gladly buy a beer to someone who can lighten me.
这一定很明显，但我无法弄清楚。为此，我几乎花了一整天的时间。我很乐意买一瓶啤酒给能减轻我心情的人。
File file = new File(filePath);
byte[] bytes = new byte[(int)file.length()];
DataInputStream dataInputStream = new DataInputStream(new BufferedInputStream(new FileInputStream(filePath)));
dataInputStream.readFully(bytes);
dataInputStream.close();
return new String(bytes);
This is my code. I see that the byte array size is not OK, but I can't figure out the right size. Besides that the contents are not also incorrect. It seems that only the text characters are OK.
这是我的代码。我看到字节数组大小不正确，但我无法弄清楚正确的大小。除此之外，内容也不正确。似乎只有文本字符是可以的。
It seems get out the data from a binary file is a real pain, I'm really depressed.
从二进制文件中取出数据似乎很痛苦，我真的很郁闷。
One more thing: the file contents are not text, it can be anything like a picture, video, or pdf.
还有一件事：文件内容不是文本，它可以是图片、视频或 pdf 之类的任何内容。
回答by Jon Skeet
If you're reading a binary file you should nottry to treat it as if it were encoded text. It's inappropriate to convert it to a string like this - you should keep it as a byte array. If you reallyneed it as text, you should use base64 or hex to represent the binary data - other approaches are likely to lose data.
如果你正在读一个二进制文件，你应该不尝试把它当作好像它编码的文本。将其转换为这样的字符串是不合适的 - 您应该将其保留为字节数组。如果你真的需要它作为文本，你应该使用 base64 或 hex 来表示二进制数据 - 其他方法可能会丢失数据。
If readFullyreturned without an exception, that shows it's read as much data as you requested, which should be the whole file. You've managed to get the data from a binary file fairly easily (although the close()call should be in a finally block) - it's only converting it to text which is a bad idea.
如果readFully无一例外地返回，则表明它读取的数据与您请求的一样多，这应该是整个文件。您已经设法相当容易地从二进制文件中获取数据（尽管close()调用应该在 finally 块中） - 它只是将其转换为文本，这是一个坏主意。
回答by Pablo Grisafi
As Jon Skeet told you (and you should always listen someone with 347k!), if it is not a text, do not save it in a string and keep it as a byte array. Also, try commons-io and use its helper classes.
正如 Jon Skeet 告诉你的（你应该总是听 347k 的人！），如果它不是文本，不要将它保存在字符串中并将其保存为字节数组。另外，试试 commons-io 并使用它的辅助类。
File file = new File(filePath);
InputStream is = null;
byte[] bytes = null;
try{
bytes = IOUtils.toByteArray(is);
}finally{
IOUtils.closeQuietly(is)
}
