手动实现转换流
stream.Transform 类继承自 stream.Duplex，并且实现了自有的 writable._write() 和 readable._read() 方法。 自定义的转换流必须实现 transform._transform() 方法，transform._flush() 方法是可选的。
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| const crypto = require("crypto");
const fs = require("fs");
const { Transform } = require("stream");
var pwd = "12345678"; //秘钥必须为：8/16/32位
class DecryptFileStream extends Transform {
constructor(aes) {
super();
if (aes) {
const key = Buffer.from(aes, "base64");
const decipher = crypto.createDecipheriv("aes-128-ecb", key, "");
decipher.setAutoPadding(true);
this._decipher = decipher;
} else {
this._decipher = null;
}
}
}
DecryptFileStream.prototype._transform = function (data, encoding, callback) {
if (this._decipher) {
this.push(this._decipher.update(data));
} else {
this.push(data);
}
callback();
};
DecryptFileStream.prototype._flush = function (data, encoding, callback) {
if (this._decipher) {
this.push(this._decipher.final());
}
callback();
};
const readS = fs.createReadStream("./2.jpeg");
const writeS = fs.createWriteStream("./4.jpeg");
const decryptStream = new DecryptFileStream(pwd);
readS.pipe(decryptStream).pipe(writeS);
|