/**
* Created by Administrator on 2016/3/21.
*/
var fs = require('fs');
var fruitBowl = ['apple', 'orange', 'banana', 'grapes'];
function writeFruit(fd){
if (fruitBowl.length){
var fruit = fruitBowl.pop() + " ";
// fs.write(fd, buffer, offset, length[, position], callback);
// fs.write(fd, string[, position[, encoding]], callback);
// fs.write = function(fd, buffer, offset, length, position, callback)
fs.write(fd, fruit, null, null, function(err, bytes){
if (err){
console.log("File Write Failed.");
} else {
console.log("Wrote: %s %dbytes", fruit, bytes);
writeFruit(fd);
}
});
} else {
fs.close(fd);
ayncRead();
}
}
fs.open('data/fruit.txt', 'w', function(err, fd){
writeFruit(fd);
});
function ayncRead()
{
var fs = require('fs');
function readFruit(fd, fruits){
var buf = new Buffer(5);
buf.fill();
//fs.read = function(fd, buffer, offset, length, position, callback)
fs.read(fd, buf, 0, 5, null, function(err, bytes, data){
if ( bytes > 0) {
console.log("read %dbytes", bytes);
fruits += data;
readFruit(fd, fruits);
} else {
fs.close(fd);
console.log ("Fruits: %s", fruits);
}
});
}
fs.open('data/fruit.txt', 'r', function(err, fd){
readFruit(fd, "");
});
}
"C:Program Files (x86)JetBrainsWebStorm 11.0.3binrunnerw.exe" F:nodejsnode.exe asyncReadWrite.js
Wrote: grapes 7bytes
Wrote: banana 7bytes
Wrote: orange 7bytes
Wrote: apple 6bytes
read 5bytes
read 5bytes
read 5bytes
read 5bytes
read 5bytes
read 2bytes
Fruits: grapes banana orange apple Process finished with exit code 0
4.流式读写
/**
* Created by Administrator on 2016/3/21.
*/
var fs = require('fs');
var grains = ['wheat', 'rice', 'oats'];
var options = { encoding: 'utf8', flag: 'w' };
//从下面的系统api可以看到 createWriteStream 就是创建了一个writable流
//fs.createWriteStream = function(path, options) {
// return new WriteStream(path, options);
//};
//
//util.inherits(WriteStream, Writable);
//fs.WriteStream = WriteStream;
//function WriteStream(path, options)
var fileWriteStream = fs.createWriteStream("data/grains.txt", options);
fileWriteStream.on("close", function(){
console.log("File Closed.");
//流式读
streamRead();
});
while (grains.length){
var data = grains.pop() + " ";
fileWriteStream.write(data);
console.log("Wrote: %s", data);
}
fileWriteStream.end();//流式读
function streamRead()
