我需要创建一个程序来读取文档,对其进行加密,然后将结果写入另一个文档。所有这些都应该使用转换流来完成。这是我的代码:
"use strict";
const fs = require("fs");
const crypto = require("crypto");
const Transform = require("stream").Transform;
// Make read and write streams
const input = fs.createReadStream("./logs/data.txt");
let output = fs.createWriteStream("./logs/newdata.txt");
// 2 functions that encrypt data and transform it
class CT extends Transform {
constructor() {
super();
}
// Encryption function
makeHash(err, data) {
if (err) throw err;
return crypto.createHash("md5").update(data).digest("hex")
}
// Encryption function will be passed as a callback
_transform(data, encoding, callback) {
callback(null, data);
}
}
let data;
// Make transform stream
let tr = new CT;
input.on("readable", () => {
while (data = input.read()) {
tr._transform(data, "utf8", tr.makeHash);
console.log(data.toString());
console.log(tr.makeHash(null, data));
output.write(data, "utf8", () => {
output.end();
console.log("Done writing the file");
});
}
});
input.on("error", (err) => {
console.error(`Unexpected ${err}`);
});
input.on("end", () => {
console.log("Done reading the file");
});
当我运行该程序时,控制台向我显示:
TextInfo
a0b5dfe30f8028ab86b1bb48b8f42ebb
Done reading the file
Done writing the file
这意味着它最初会读写文档,但结果未加密(“ TextInfo”)-而是看起来像这样的“ a0b5dfe30f8028ab86b1bb48b8f42ebb”。我确定转换流逻辑中有一个错误。
任何帮助将不胜感激!
最佳答案
我的错误#1是我创建了一个读取流-相反,我应该只声明读取文件的变量输入,并且在回调函数中擅长使用转换流来写入其内容。
错误#2是我错误地实现了功能makeHash:现在,它完美地加密并写入了文件。因此,此函数称为_transform函数的回调。
这是工作代码:
"use strict";
const fs = require("fs");
const crypto = require("crypto");
const Transform = require("stream").Transform;
const input = fs.readFile("./logs/data.txt", "utf8", (err, content) => {
if (err) throw err;
tr.write(content);
});
let output = fs.createWriteStream("./logs/newdata.txt");
class CT extends Transform {
constructor() {
super();
}
// Function declares cData - encrypted input text and writes it to the file
makeHash(err, data) {
let cData = crypto.createHash("md5").update(data).digest("hex");
output.write(cData, "utf8", () => {
output.end();
console.log("Done writing the file");
});
}
_transform(chunk, encoding, callback) {
callback(null, chunk);
}
}
let tr = new CT;
tr.on("data", (chunk) => tr._transform(chunk, "utf8", tr.makeHash));
tr.on("error", (err) => {
console.error(`Unexpected ${err}`);
});