node中的读取流createReadStream、写入流createWriteStream和管道流pipe

梦里梦外; 2021-07-25 13:27 1122阅读 0赞

## 一、读取流createReadStream ##

现在在data目录下有input.txt文件，其内容很多，如下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 1][]

## 二、写入流createWriteStream ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 2][]

结果如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 3][]

const fs = require('fs')
    
    let str = ""
    for (let i = 0; i < 500; i++){
        str+='这是写入流输出的数据\n'
    }
    
    let writeStream = fs.createWriteStream('./data/output.txt');
    
    writeStream.write(str)
    
    writeStream.end();//只有添上这句代码，下面的finish事件才能被监听
    
    writeStream.on('finish', () => {
        console.log('写入完成')
    })

## 三、管道流pipe ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 4][]

const fs = require('fs')
    
    let readStream = fs.createReadStream('./data/input.txt');
    let writeStream = fs.createWriteStream('./data/output.txt');
    
    //读取input.txt文件内容，并将内容写入到output.txt文件中(原内容会被替换)
    readStream.pipe(writeStream)
    
    console.log('程序执行完毕')

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 5][]

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