Node.js 之Buffer缓冲区

如何创建Buffer类

var buf = new Buffer(10);

var buf = new Buffer([10,20,30,40,50]);

var buf = new Buffer("www.runoob.com","utf-8");

如何写入缓冲区

buf.write(string,[,offet][,length][,encoding]);

buf = new Buffer(256);
len = buf.write("www.runoob.com");

console.log("写入字节数 : "+  len);

$node main.js
写入字节数：14

从缓冲区读取数据 语法

buf.toString([encoding][,start][,end])

buf = new Buffer(26);
for (var i = 0 ; i < 26 ; i++) {
buf[i] = i + 97;
}

console.log( buf.toString('ascii'));       // 输出: abcdefghijklmnopqrstuvwxyz
console.log( buf.toString('ascii',0,5));   // 输出: abcde
console.log( buf.toString('utf8',0,5));    // 输出: abcde
console.log( buf.toString(undefined,0,5)); // 使用 'utf8' 编码, 并输出: abcde

abcdefghijklmnopqrstuvwxyz
abcde
abcde
abcde

将Buffer转成为JSON对象

buf.toJSON()

var buf = new Buffer('www.runoob.com');
var json = buf.toJSON();
console.log(json);

{ type: 'Buffer',
data: [ 119, 119, 119, 46, 98, 97, 105, 100, 117, 46, 99, 111, 109 ] }

缓冲区合并

Buffer.concat(list[,totalLength])

var buffer1 = new Buffer("我是菜鸟");
var buffer2 = new Buffer("www.runoob.com");
var buffer3 = Buffer.concat([buffer1,buffer2]);
console.log("buffer3 内容:"+buffer3.toString());

buffer3 内容：我是菜鸟www.runoob.com

缓冲区比较

var buffer1 = new Buffer('ABC');
var buffer2 = new Buffer('ABCD');
var result = buffer1.compare(buffer2);

if(result < 0) {
console.log(buffer1 + " 在 " + buffer2 + "之前");
}else if(result == 0){
console.log(buffer1 + " 与 " + buffer2 + "相同");
}else {
console.log(buffer1 + " 在 " + buffer2 + "之后");
}

ABC在ABCD之前

缓冲区拷贝

buf.copy(targetBuffer[,targetStart][,sourceStart][,sourceEnd])

var buffer1 = new Buffer('ABC');
// 拷贝一个缓冲区
var buffer2 = new Buffer(3);
buffer1.copy(buffer2);
console.log("buffer2 content: " + buffer2.toString());

buffer2 content: ABC

缓冲区裁剪

buf.slice([start][, end])

var buffer1 = new Buffer('runoob');
// 剪切缓冲区
var buffer2 = buffer1.slice(0,2);
console.log("buffer2 content: " + buffer2.toString());

buffer2 content: ru

缓冲区长度

but.length;

var buffer = new Buffer('www.runoob.com');
//  缓冲区长度
console.log("buffer length: " + buffer.length);

buffer length: 14

方法参考手册

var b = new Buffer(6);
b.writeUIntBE(0x1234567890ab, 0, 6);
// <Buffer 12 34 56 78 90 ab>