Buffer.alloc(size[, fill[, encoding]])： 返回一个指定大小的 Buffer 实例，如果没有设置 fill，则默认填满 0
Buffer.from(array)： 返回一个被 array 的值初始化的新的 Buffer 实例（传入的 array 的元素只能是数字，不然就会自动被 0 覆盖）
写入缓冲区
buf = Buffer.alloc(256);
len = buf.write("www.runoob.com");
console.log("写入字节数 : "+ len);
//$node main.js
//写入字节数 : 14
读取
buf = Buffer.alloc(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
转换json对象
const buf = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5]);
const json = JSON.stringify(buf);
// 输出: {"type":"Buffer","data":[1,2,3,4,5]}
console.log(json);
const copy = JSON.parse(json, (key, value) => {
return value && value.type === 'Buffer' ?
Buffer.from(value.data) :
value;
});
// 输出: <Buffer 01 02 03 04 05>
console.log(copy);
合并
var buffer1 = Buffer.from(('菜鸟教程'));
var buffer2 = Buffer.from(('www.runoob.com'));
var buffer3 = Buffer.concat([buffer1,buffer2]);
console.log("buffer3 内容: " + buffer3.toString());
比较
参数有三个返回值,result
var buffer1 = Buffer.from('ABC');
var buffer2 = Buffer.from('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
拷贝
var buf1 = Buffer.from('abcdefghijkl');
var buf2 = Buffer.from('RUNOOB');
//将 buf2 插入到 buf1 指定位置上
buf2.copy(buf1, 2);
console.log(buf1.toString());
//abRUNOOBijkl
裁剪
var buffer1 = Buffer.from('runoob');
// 剪切缓冲区
var buffer2 = buffer1.slice(0,2);
console.log("buffer2 content: " + buffer2.toString());
//输出buffer2 content: ru
长度
var buffer = Buffer.from('www.runoob.com');
// 缓冲区长度
console.log("buffer length: " + buffer.length);
