在node.js中读取二进制数据 [英] Reading binary data in node.js
问题描述
我在读取node.js中的二进制数据时遇到问题.这就是我要做的:
I'm having problems reading binary data in node.js. This is what I do:
$ cat test.js
var fs = require('fs'),
binary = fs.readFileSync('./binary', 'binary').toString('binary');
process.stdout.write(binary.substring(0, 48));
$ xxd binary
00000000: 7f45 4c46 0201 0100 0000 0000 0000 0000 .ELF............
00000010: 0300 3e00 0100 0000 0008 0000 0000 0000 ..>.............
00000020: 4000 0000 0000 0000 10a0 0000 0000 0000 @...............
$ node test.js | xxd
00000000: 7f45 4c46 0201 0100 0000 0000 0000 0000 .ELF............
00000010: 0300 3e00 0100 0000 0008 0000 0000 0000 ..>.............
00000020: 4000 0000 0000 0000 10c2 a000 0000 0000 @...............
00000030: 00 .
$
请注意,使用节点读取时,如何在索引0x29处插入0xc2字节.这是为什么?我已经说过对readFileSync
和toString
都进行了二进制编码.
我也尝试过ascii,但结果却不同,同样错误.
Notice how a 0xc2 byte is inserted at index 0x29 when reading with node. Why is that? I've stated binary encoding both to readFileSync
and toString
.
I've also tried ascii but then I get a different and equally wrong result.
推荐答案
'binary'
编码是'latin1'
的别名,在读取非字符数据时,您显然不希望使用它.
The 'binary'
encoding is an alias for 'latin1'
, which you clearly don't want when reading non-character data.
如果您想要原始数据,完全不要指定编码(或供应null
)*.您将得到一个 Buffer
而不是一个字符串,然后您会想要直接使用而不是在其上使用toString
.
If you want the raw data, don't specify an encoding at all (or supply null
)*. You'll get a Buffer
instead of a string, which you'd then want to use directly rather than using toString
on it.
*(某些API [例如fs.watch
]也接受'buffer'
,但它不在 和readFileSync
的编码列表没有说明.[感谢 Patrick 提供列表链接.])
* (Some APIs [like fs.watch
] also accept 'buffer'
, but it's not on the list of encodings and readFileSync
doesn't say it does. [Thanks Patrick for providing the list link.])
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