javascript以post方式实现文件的导出或下载
当用GET方式来实现文件（excel、pdf、doc）导出或下载的时候，传参比较简单直接放到url里面，常用的导出方法有：
1>window.open(url参数)，来实现文件的导出。
2>动态添加a标签,来实现文件的导出。
当使用post来实现文件导出或下载的时候传参是一个问题，要知道不管是window.open还是a标签只能get方式请求，在网上查找了关于用post实现传参来导出文件或下载，然而并没有合适的解决办法。查了javascript权威指南结合自己的项目，找到了一种非常非常非常好的方法来实现文件以GET方式导出。长话短说，下面是解决方案：
所有浏览器都支持XMLHttpRequest对象（不了解的童鞋查看javascript权威指南），它定义了用脚本操作HTTP的API。这个API包含实现POST请求的能力。XHR2还定义了一种将URL指定的内容以Blob（二进制）的形式下载下来。
例子：使用XMLHttpRequest下载Blob
function(){
var
xhr =
new
XMLHttpRequest();
//创建新的XHR对象 xhr
.
open
(
'post'
,
url
);
//指定获取数据的方式和url地址 xhr.
setRequestHeader(
'Content-Type',
'application/json;
charset=UTF-8') xhr.
responseType =
'blob';
//以blob的形式接收数据，一般文件内容比较大 xhr.
onload =
function(
e) { var
blob =
this.
response;
//Blob数据 if (
this.
status ==
200) { if (
blob &&
blob.
size >
0) { saveAs(
blob,
fileName);
//处理二进制数据，让浏览器认识它 } } };
xhr.send(params) //post请求传的参数
}
那么问题来了saveAs是个什么东东呢，点击打开链接简而言支，有人贡献了一份js来处理二进制数据，里面有个文件FileSiver.js里面的方法saveAs()来处理二进制数据来实现文件导出。直接引用这个js文件然后调用就行。
附saveAs()方法内容（重要哦）
/* FileSaver.js
* A saveAs() FileSaver implementation.
* 1.3.8
* 2018-03-22 14:03:47
*
* By Eli Grey, https://eligrey.com
* License: MIT
*See https://github.com/eligrey/FileSaver.js/blob/master/LICENSE.md
*/
/*global self */
/*jslint bitwise: true, indent: 4, laxbreak: true, laxcomma: true, smarttabs: true, plusplus: true */
/*! @source http://purl.eligrey.com/github/FileSaver.js/blob/master/src/FileSaver.js */
var saveAs = saveAs || (function(view) {
"use strict";
// IE <10 is explicitly unsupported
if (typeof view === "undefined" || typeof navigator !== "undefined" && /MSIE [1-9]\./.test(navigator.userAgent)) {
return;
}
var
doc = view.document
// only get URL when necessary in case Blob.js hasn't overridden it yet
, get_URL = function() {
return view.URL || view.webkitURL || view;
}
, save_link = doc.createElementNS("http://www.w3.org/1999/xhtml", "a")
, can_use_save_link = "download" in save_link
, click = function(node) {
var event = new MouseEvent("click");
node.dispatchEvent(event);
}
, is_safari = /constructor/i.test(view.HTMLElement) || view.safari
, is_chrome_ios =/CriOS\/[\d]+/.test(navigator.userAgent)
, setImmediate = view.setImmediate || view.setTimeout
, throw_outside = function(ex) {
setImmediate(function() {
throw ex;
}, 0);
}
, force_saveable_type = "application/octet-stream"
// the Blob API is fundamentally broken as there is no "downloadfinished" event to subscribe to
, arbitrary_revoke_timeout = 1000 * 40 // in ms
, revoke = function(file) {
var revoker = function() {
if (typeof file === "string") { // file is an object URL
get_URL().revokeObjectURL(file);
} else { // file is a File
file.remove();
}
};
setTimeout(revoker, arbitrary_revoke_timeout);
}
, dispatch = function(filesaver, event_types, event) {
event_types = [].concat(event_types);
var i = event_types.length;
while (i--) {
var listener = filesaver["on" + event_types[i]];
if (typeof listener === "function") {
try {
listener.call(filesaver, event || filesaver);
} catch (ex) {
throw_outside(ex);
}
}
}
}
, auto_bom = function(blob) {
// prepend BOM for UTF-8 XML and text/* types (including HTML)
// note: your browser will automatically convert UTF-16 U+FEFF to EF BB BF
if (/^\s*(?:text\/\S*|application\/xml|\S*\/\S*\+xml)\s*;
.*charset\s*=\s*utf-8/i.test(blob.type)) {
return new Blob([String.fromCharCode(0xFEFF), blob], {type: blob.type});
}
return blob;
}
, FileSaver = function(blob, name, no_auto_bom) {
if (!no_auto_bom) {
blob = auto_bom(blob);
}
// First try a.download, then web filesystem, then object URLs
var
filesaver = this
, type = blob.type
, force = type === force_saveable_type
, object_url
, dispatch_all = function() {
dispatch(filesaver, "writestart progress write writeend".split(" "));
}
// on any filesys errors revert to saving with object URLs
, fs_error = function() {
if ((is_chrome_ios || (force && is_safari)) && view.FileReader) {
// Safari doesn't allow downloading of blob urls
var reader = new FileReader();
reader.onloadend = function() {
var url = is_chrome_ios ? reader.result : reader.result.replace(/^data:[^;
]*;
/, 'data:attachment/file;
');
var popup = view.open(url, '_blank');
if(!popup) view.location.href = https://www.it610.com/article/url;
url=undefined;
// release reference before dispatching
filesaver.readyState = filesaver.DONE;
dispatch_all();
};
reader.readAsDataURL(blob);
filesaver.readyState = filesaver.INIT;
return;
}
// don't create more object URLs than needed
if (!object_url) {
object_url = get_URL().createObjectURL(blob);
}
if (force) {
view.location.href = https://www.it610.com/article/object_url;
} else {
var opened = view.open(object_url, "_blank");
if (!opened) {
// Apple does not allow window.open, see https://developer.apple.com/library/safari/documentation/Tools/Conceptual/SafariExtensionGuide/WorkingwithWindowsandTabs/WorkingwithWindowsandTabs.html
view.location.href = https://www.it610.com/article/object_url;
}
}
filesaver.readyState = filesaver.DONE;
dispatch_all();
revoke(object_url);
}
;
filesaver.readyState = filesaver.INIT;
if (can_use_save_link) {
object_url = get_URL().createObjectURL(blob);
setImmediate(function() {
save_link.href = https://www.it610.com/article/object_url;
save_link.download = name;
click(save_link);
dispatch_all();
revoke(object_url);
filesaver.readyState = filesaver.DONE;
}, 0);
return;
}
fs_error();
}
, FS_proto = FileSaver.prototype
, saveAs = function(blob, name, no_auto_bom) {
return new FileSaver(blob, name || blob.name || "download", no_auto_bom);
}
;
// IE 10+ (native saveAs)
if (typeof navigator !== "undefined" && navigator.msSaveOrOpenBlob) {
return function(blob, name, no_auto_bom) {
name = name || blob.name || "download";
if (!no_auto_bom) {
blob = auto_bom(blob);
}
return navigator.msSaveOrOpenBlob(blob, name);
};
}
// todo: detect chrome extensions & packaged apps
//save_link.target = "_blank";
FS_proto.abort = function(){};
FS_proto.readyState = FS_proto.INIT = 0;
FS_proto.WRITING = 1;
FS_proto.DONE = 2;
FS_proto.error =
FS_proto.onwritestart =
FS_proto.onprogress =
FS_proto.onwrite =
FS_proto.onabort =
FS_proto.onerror =
FS_proto.onwriteend =
null;
return saveAs;
}(
typeof self !== "undefined" && self
|| typeof window !== "undefined" && window
|| this
));
【javascript以post方式实现文件的导出或下载】
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