Pure Javascript is Unicode friendly but not nice to binary data. When dealing with TCP streams or the file system, it's necessary to handle octet streams. Node has several strategies for manipulating, creating, and consuming octet streams.
纯Javascript语言是Unicode友好性的，但是难以处理二进制数据。在处理TCP流和文件系统时经常需要操作字节流。Node提供了一些列机制，用于操作、创建、以及消耗（consuming）字节流。
Raw data is stored in instances of the Buffer class. A Buffer is similar
to an array of integers but corresponds to a raw memory allocation outside
the V8 heap. A Buffer cannot be resized.
在实例化的Buffer类中存储了原始数据。Buffer类似于一个整数数组，但Buffer对应了在V8堆（the V8 heap）外的原始存储空间分配。一旦创建了Buffer实例，则无法改变其大小。
The Buffer object is global.
另外，Buffer是一个全局对象。
Converting between Buffers and JavaScript string objects requires an explicit encoding method. Here are the different string encodings;
在缓冲器（Buffers）和JavaScript间进行字符串的转换需要调用特定的编码方法。如下列举了不同的编码方法：
'ascii' - for 7 bit ASCII data only. This encoding method is very fast, and will
strip the high bit if set.
'ascii' - 仅对应7位的ASCII数据。虽然这种编码方式非常迅速，并且如果设置了最高位，则会将其移去。
'utf8' - Multi byte encoded Unicode characters. Many web pages and other document formats use UTF-8.
'utf8' - 对应多字节编码Unicode字符。大量网页和其他文件格式使用这类编码方式。
'ucs2' - 2-bytes, little endian encoded Unicode characters. It can encode
only BMP(Basic Multilingual Plane, U+0000 - U+FFFF).
'ucs2' - 2字节的，低字节序编码Unicode字符。只能编码BMP（第零平面，U+0000 - U+FFFF）字符。
'base64' - Base64 string encoding.
'base64' - Base64 字符串编码.
'binary' - A way of encoding raw binary data into strings by using only
the first 8 bits of each character. This encoding method is depreciated and
should be avoided in favor of Buffer objects where possible. This encoding
will be removed in future versions of Node.
'binary' - 仅使用每个字符的头8位将原始的二进制信息进行编码。在需使用Buffer的情况下，应该尽量避免使用这个已经过时的编码方式。而且，这个编码方式不会出现在未来版本的Node中。
'hex' - Encode each byte as two hexidecimal characters.
'hex' - 将一个字节编码为两个16进制字符。
Allocates a new buffer of size octets.
分配给一个新创建的buffer实例一个大小为size字节的空间。
Allocates a new buffer using an array of octets.
使用array的空间创建一个buffer实例。
Allocates a new buffer containing the given str.
创建一个包含给定str的buffer实例。
Writes string to the buffer at offset using the given encoding. Returns
number of octets written. If buffer did not contain enough space to fit
the entire string, it will write a partial amount of the string. In the case
of 'utf8' encoding, the method will not write partial characters.
通过给定的编码方式把string写入到buffer的offset（偏移地址）中，并且返回写入的字节数。如果当前的buffer没有足够存储空间，字符串会部分地保存在buffer中，而不是整串字符。需要注意的是，如果使用'utf8'进行编码，该方法不会对零散的字符进行编写。
Example: write a utf8 string into a buffer, then print it
例如：将一串utf8格式的字符串写入Buffer，然后输出：
buf = new Buffer(256);
len = buf.write('\u00bd + \u00bc = \u00be', 0);
console.log(len + " bytes: " + buf.toString('utf8', 0, len));
// 12 bytes: ½ + ¼ = ¾Decodes and returns a string from buffer data encoded with encoding
beginning at start and ending at end.
对缓冲器中的以encoding方式编码的，以start标识符开始，以end标识符结尾的缓冲数据进行解码，并输出字符串。
See buffer.write() example, above.
参见上文的buffer.write()例子。
Get and set the octet at index. The values refer to individual bytes,
so the legal range is between 0x00 and 0xFF hex or 0 and 255.
获取或者设置位于index字节的值。由于返回值为单个的字节，因此其范围应该在0x00 到 0xFF（16进制）或者0 and 255（10进制）之间
Example: copy an ASCII string into a buffer, one byte at a time:
例如：通过每次仅输入一个字符的方式将整串ASCII字符录入Buffer中：
str = "node.js";
buf = new Buffer(str.length);
for (var i = 0; i < str.length ; i++) {
buf[i] = str.charCodeAt(i);
}
console.log(buf);
// node.jsTests if obj is a Buffer.
验证obj的类别是否为Buffer类。
Gives the actual byte length of a string. This is not the same as
String.prototype.length since that returns the number of characters in a
string.
返回字符串长度的实际值。与String.prototype.length的区别之处在于该方法返回的是字符串中characters的个数。
Example:
例如：
str = '\u00bd + \u00bc = \u00be';
console.log(str + ": " + str.length + " characters, " +
Buffer.byteLength(str, 'utf8') + " bytes");
// ½ + ¼ = ¾: 9 characters, 12 bytesThe size of the buffer in bytes. Note that this is not necessarily the size
of the contents. length refers to the amount of memory allocated for the
buffer object. It does not change when the contents of the buffer are changed.
返回Buffer占用的字节数。需要注意的是，length并非其内容占的大小，而是指分配给Buffer实例的存储空间的大小，因此该值不会随Buffer内容的变化而变化。
buf = new Buffer(1234);
console.log(buf.length);
buf.write("some string", "ascii", 0);
console.log(buf.length);
// 1234
// 1234Does a memcpy() between buffers.
在两个Buffer之间进行memcpy() 操作。
Example: build two Buffers, then copy buf1 from byte 16 through byte 19
into buf2, starting at the 8th byte in buf2.
例如：创建2个Buffer实例，然后将buf1中第16字节到第19字节间的信息复制到buf2中，并使在buf2中新的字符串首字符位于第8字节：
buf1 = new Buffer(26);
buf2 = new Buffer(26);
for (var i = 0 ; i < 26 ; i++) {
buf1[i] = i + 97; // 97 is ASCII a
buf2[i] = 33; // ASCII !
}
buf1.copy(buf2, 8, 16, 20);
console.log(buf2.toString('ascii', 0, 25));
// !!!!!!!!qrst!!!!!!!!!!!!!Returns a new buffer which references the
same memory as the old, but offset and cropped by the start and end
indexes.
返回一个和原Buffer引用相同存储空间的新Buffer，但是新Buffer中的偏移地址截取了原Buffer偏移地址中自start到end的部分。
Modifying the new buffer slice will modify memory in the original buffer!
特别注意：通过修改新的Buffer切片（slice）中的内容同样会修改存储在原Buffer中的信息！
Example: build a Buffer with the ASCII alphabet, take a slice, then modify one byte from the original Buffer.
例如：建立一个ASCII码型的字母表，再建立一个切片，并在原Buffer中修改一个字节：
var buf1 = new Buffer(26);
for (var i = 0 ; i < 26 ; i++) {
buf1[i] = i + 97; // 97 is ASCII a
}
var buf2 = buf1.slice(0, 3);
console.log(buf2.toString('ascii', 0, buf2.length));
buf1[0] = 33;
console.log(buf2.toString('ascii', 0, buf2.length));
// abc
// !bc