我正在入侵一个Node程序，该程序使用SMTP协议捕获SMTP电子邮件并对邮件数据采取行动。库将邮件数据作为流提供，但我不知道如何将其转换为字符串。
我目前正在用stream.pipe(process. pipe)将其写入标准输出。stdout， {end: false})，但正如我所说的，我需要一个字符串中的流数据，一旦流结束，我就可以使用它。
我如何收集所有的数据从一个Node.js流到一个字符串?
当前回答
你觉得这个怎么样?
async function streamToString(stream) {
// lets have a ReadableStream as a stream variable
const chunks = [];
for await (const chunk of stream) {
chunks.push(Buffer.from(chunk));
}
return Buffer.concat(chunks).toString("utf-8");
}
其他回答
最简洁的解决方案可能是使用“string-stream”包，它将流转换为带有承诺的字符串。
const streamString = require('stream-string')
streamString(myStream).then(string_variable => {
// myStream was converted to a string, and that string is stored in string_variable
console.log(string_variable)
}).catch(err => {
// myStream emitted an error event (err), so the promise from stream-string was rejected
throw err
})
像减流器这样的东西怎么样?
下面是一个使用ES6类的例子如何使用一个。
var stream = require('stream')
class StreamReducer extends stream.Writable {
constructor(chunkReducer, initialvalue, cb) {
super();
this.reducer = chunkReducer;
this.accumulator = initialvalue;
this.cb = cb;
}
_write(chunk, enc, next) {
this.accumulator = this.reducer(this.accumulator, chunk);
next();
}
end() {
this.cb(null, this.accumulator)
}
}
// just a test stream
class EmitterStream extends stream.Readable {
constructor(chunks) {
super();
this.chunks = chunks;
}
_read() {
this.chunks.forEach(function (chunk) {
this.push(chunk);
}.bind(this));
this.push(null);
}
}
// just transform the strings into buffer as we would get from fs stream or http request stream
(new EmitterStream(
["hello ", "world !"]
.map(function(str) {
return Buffer.from(str, 'utf8');
})
)).pipe(new StreamReducer(
function (acc, v) {
acc.push(v);
return acc;
},
[],
function(err, chunks) {
console.log(Buffer.concat(chunks).toString('utf8'));
})
);
你觉得这个怎么样?
async function streamToString(stream) {
// lets have a ReadableStream as a stream variable
const chunks = [];
for await (const chunk of stream) {
chunks.push(Buffer.from(chunk));
}
return Buffer.concat(chunks).toString("utf-8");
}
我更幸运的是这样使用:
let string = '';
readstream
.on('data', (buf) => string += buf.toString())
.on('end', () => console.log(string));
我使用节点v9.11.1, readstream是来自http的响应。回调。
以上这些方法对我都没用。我需要使用Buffer对象:
const chunks = [];
readStream.on("data", function (chunk) {
chunks.push(chunk);
});
// Send the buffer or you can put it into a var
readStream.on("end", function () {
res.send(Buffer.concat(chunks));
});
