1、文件流寫入
const fs = require("fs");
const ws = fs.createWriteStream("test.txt",{
flags:"w",
encoding:"utf-8"
});
for(let i = 0;i < 10000;i++){
ws.write("第"+i+"行\r\n",{
encoding:"utf-8"
},(err)=>{
if(err) console.log("文件寫入失敗");
console.log("正在寫入...");
});
}
ws.end();//標記文件寫入完成
ws.on("open",()=>{
console.log("文件被打開");
})
ws.on("ready",()=>{
console.log("文件已準備就緒,即將開始寫入");
})
ws.on("close",()=>{//文件寫入完成後會觸發
console.log("文件關閉,禁止寫入");
});
ws.on("error",()=>{
console.log("文件寫入失敗");
});
2、文件流讀取
const fs = require("fs");
const rs = fs.createReadStream("test.txt",{flags:"r",encoding:"utf-8"});//創建讀取文件入口
let str = "";
rs.on("data",(chunk)=>{//監聽數據的流入
str += chunk;
});
rs.on("open",()=>{
console.log("文件已打開");
}).on("ready",()=>{
console.log("文件已準備就緒,即將讀取");
}).on("end",()=>{
console.log(str);
console.log("文件流讀取完成");
}).on("error",()=>{
console.log("讀取文件失敗");
});
3、讀取某個文件,寫入到另一個文件中
const fs = require("fs");
const rs = fs.createReadStream("test.txt");
const ws = fs.createWriteStream("testcopy.txt",{encoding:"utf-8"});
rs.on("data",(chunk)=>{
console.log(chunk.length);
ws.write(chunk);
});
rs.on("close",()=>{
console.log("文件流讀取完成");
ws.end();
}).on("error",()=>{
console.log("文件流讀取出錯");
});
ws.on("close",()=>{
console.log("文件寫入完成");
});
4、使用pipe可實現第三個案例,pipe的原理類似於第三個案例
rs.pipe(ws);