本文主要包含FileReader,html5,读取等相关知识,匿名希望在学习及工作中可以帮助到您
这次给大家带来H5的文件域FileReader怎样分段读取文件上传到服务器，H5的文件域FileReader分段读取文件上传到服务器的注意事项有哪些，下面就是实战案例，一起来看一下。
说明：使用Ajax方式上传，文件不能过大，最好小于三四百兆，因为过多的连续Ajax请求会使后台崩溃，获取InputStream中数据会为空，尤其在Google浏览器测试过程中。
1.简单分段读取文件为Blob，ajax上传到服务器
<div class="container">
<div class="panel panel-default">
<div class="panel-heading">分段读取文件：</div>
<div class="panel-body">
<input type="file" id="file" />
<blockquote style="word-break:break-all;"></blockquote>
</div>
</div>
</div>JS：
/*
* 分段读取文件为blob ，并使用ajax上传到服务器
* 分段上传exe文件会抛出异常
*/
var fileBox = document.getElementById('file');
file.onchange = function () {
//获取文件对象
var file = this.files[0];
var reader = new FileReader();
var step = 1024 * 1024;
var total = file.size;
var cuLoaded = 0;
console.info("文件大小：" + file.size);
var startTime = new Date();
//读取一段成功
reader.onload = function (e) {
//处理读取的结果
var loaded = e.loaded;
//将分段数据上传到服务器
uploadFile(reader.result, cuLoaded, function () {
console.info('loaded:' + cuLoaded + 'current:' + loaded);
//如果没有读完，继续
cuLoaded += loaded;
if (cuLoaded < total) {
readBlob(cuLoaded);
} else {
console.log('总共用时：' + (new Date().getTime() - startTime.getTime()) / 1000);
cuLoaded = total;
}
});
}
//指定开始位置，分块读取文件
function readBlob(start) {
//指定开始位置和结束位置读取文件
//console.info('start:' + start);
var blob = file.slice(start, start + step);
reader.readAsArrayBuffer(blob);
}
//开始读取
readBlob(0);
//关键代码上传到服务器
function uploadFile(result, startIndex, onSuccess) {
var blob = new Blob([result]);
//提交到服务器
var fd = new FormData();
fd.append('file', blob);
fd.append('filename', file.name);
fd.append('loaded', startIndex);
var xhr = new XMLHttpRequest();
xhr.open('post', '../ashx/upload2.ashx', true);
xhr.onreadystatechange = function () {
if (xhr.readyState == 4 && xhr.status == 200) {
// var data = eval('(' + xhr.responseText + ')');
console.info(xhr.responseText);
if (onSuccess)
onSuccess();
}
}
//开始发送
xhr.send(fd);
}
}后台代码：
/// <summary>
/// upload2 的摘要说明
/// </summary>
public class upload2 : IHttpHandler
{
LogHelper.LogHelper _log = new LogHelper.LogHelper();
int totalCount = 0;
public void ProcessRequest(HttpContext context)
{
HttpContext _Context = context;
//接收文件
HttpRequest req = _Context.Request;
if (req.Files.Count <= 0)
{
WriteStr("获取服务器上传文件失败");
return;
}
HttpPostedFile _file = req.Files[0];
//获取参数
// string ext = req.Form["extention"];
string filename = req.Form["filename"];
//如果是int 类型当文件大的时候会出问题 最大也就是 1.9999999990686774G
int loaded = Convert.ToInt32(req.Form["loaded"]);
totalCount += loaded;
string newname = @"F:\JavaScript_Solution\H5Solition\H5Solition\Content\TempFile\";
newname += filename;
//接收二级制数据并保存
Stream stream = _file.InputStream;
if (stream.Length <= 0)
throw new Exception("接收的数据不能为空");
byte[] dataOne = new byte[stream.Length];
stream.Read(dataOne, 0, dataOne.Length);
FileStream fs = new FileStream(newname, FileMode.Append, FileAccess.Write, FileShare.Read, 1024);
try
{
fs.Write(dataOne, 0, dataOne.Length);
}
finally
{
fs.Close();
stream.Close();
}
_log.WriteLine((totalCount + dataOne.Length).ToString());
WriteStr("分段数据保存成功");
}
private void WriteStr(string str)
{
HttpContext.Current.Response.Write(str);
}
public bool IsReusable
{
get
{
return true;
}
}2.分段读取文件为blob ，并使用ajax上传到服务器，追加中止、继续功能操作
<div class="container">
<div class="panel panel-default">
<div class="panel-heading">分段读取文件：</div>
<div class="panel-body">
<input type="file" id="file" />
<br />
<input type="button" value="中止" onclick="stop();" /> 
<input type="button" value="继续" onclick="containue();" />
<br />
<progress id="progressOne" max="100" value="0" style="width:400px;"></progress>
<blockquote id="Status" style="word-break:break-all;"></blockquote>
</div>
</div>
</div>JS:
/*
* 分段读取文件为blob ，并使用ajax上传到服务器
* 使用Ajax方式提交上传数据文件大小应该有限值，最好500MB以内
* 原因短时间过多的ajax请求，Asp.Net后台会崩溃获取上传的分块数据为空
* 取代方式，长连接或WebSocket
*/
var fileBox = document.getElementById('file');
var reader = null; //读取操作对象
var step = 1024 * 1024 * 3.5; //每次读取文件大小
var cuLoaded = 0; //当前已经读取总数
var file = null; //当前读取的文件对象
var enableRead = true;//标识是否可以读取文件
fileBox.onchange = function () {
//获取文件对象
file = this.files[0];
var total = file.size;
console.info("文件大小：" + file.size);
var startTime = new Date();
reader = new FileReader();
//读取一段成功
reader.onload = function (e) {
//处理读取的结果
var result = reader.result;
var loaded = e.loaded;
if (enableRead == false)
return false;
//将分段数据上传到服务器
uploadFile(result, cuLoaded, function () {
console.info('loaded:' + cuLoaded + '----current:' + loaded);
//如果没有读完，继续
cuLoaded += loaded;
if (cuLoaded < total) {
readBlob(cuLoaded);
} else {
console.log('总共用时：' + (new Date().getTime() - startTime.getTime()) / 1000);
cuLoaded = total;
}
//显示结果进度
var percent = (cuLoaded / total) * 100;
document.getElementById('Status').innerText = percent;
document.getElementById('progressOne').value = percent;
});
}
//开始读取
readBlob(0);
//关键代码上传到服务器
function uploadFile(result, startIndex, onSuccess) {
var blob = new Blob([result]);
//提交到服务器
var fd = new FormData();
fd.