JavaScript 二进制转文件

关于在javascript下，如何将二进制转换成相应的文件并下载。

首先， 我们需要得到二进制的数据以及相应的文件格式，没有相应的格式也可以，可以通过二进制来判断，但相对会麻烦很多，所以建议可以要求后端提供文件的名字来得到相应的文件格式。

http://blog.csdn.net/sdomain/article/details/4636197 这是一个二进制判断文件类型的博客 有兴趣可以看看

首先 我们拿到了二进制的数据。 在这里，我拿到的是一个对象two_object.

var two_obj = {"0":137,"1":80,"2":78,"3":71,"4":13,"5":10,"6":26,"7":10,"8":0,"9":0,"10":0,"11":13,"12":73,"13":72,"14":68,"15":82,"16":0,"17":0,"18":0,"19":38,"20":0,"21":0,"22":0,"23":38,"24":8,"25":6,"26":0,"27":0,"28":0,"29":168,"30":61,"31":233,"32":174,"33":0,"34":0,"35":0,"36":1,"37":115,"38":82,"39":71,"40":66,"41":0,"42":174,"43":206,"44":28,"45":233,"46":0,"47":0,"48":3,"49":217,"50":73,"51":68,"52":65,"53":84,"54":88,"55":9,"56":237,"57":88,"58":61,"59":104,"60":83,"61":81,"62":20,"63":206,"64":75,"65":155,"66":168,"67":196,"68":132,"69":42,"70":116,"71":113,"72":139,"73":161,"74":53,"75":33,"76":54,"77":17,"78":28,"79":170,"80":110,"81":130,"82":32,"83":88,"84":12,"85":85,"86":220,"87":28,"88":237,"89":228,"90":32,"91":34,"92":14,"93":106,"94":93,"95":181,"96":14,"97":90,"98":138,"99":131,"100":96,"101":81,"102":55,"103":87,"104":193,"105":150,"106":58,"107":137,"108":14,"109":130,"110":216,"111":193,"112":161,"113":169,"114":37,"115":49,"116":181,"117":20,"118":44,"119":20,"120":116,"121":168,"122":145,"123":40,"124":104,"125":210,"126":31,"127":191,"128":239,"129":113,"130":239,"131":243,"132":229,"133":253,"134":228,"135":221,"136":247,"137":218,"138":102,"139":234,"140":133,"141":147,"142":115,"143":207,"144":185,"145":231,"146":124,"147":231,"148":123,"149":247,"150":231,"151":253,"152":36,"153":20,"154":218,"155":105,"156":59,"157":51,"158":96,"159":159,"160":129,"161":249,"162":249,"163":249,"164":93,"165":20,"166":251,"167":136,"168":127,"169":143,"170":230,"171":63,"172":229,"173":127,"174":198,"175":236,"176":236,"177":108,"178":110,"179":125,"180":125,"181":253,"182":188,"183":166,"184":105,"185":103,"186":224,"187":77,"188":109,"189":108,"190":108,"191":236,"192":231,"193":40,"194":236,"195":21,"196":168,"197":5,"198":216,"199":175,"200":194,"201":225,"202":240,"203":139,"204":190,"205":190,"206":190,"207":34,"208":253,"209":126,"210":90,"211":32,"212":98,"213":32,"214":148,"215":65,"216":209,"217":123,"218":144,"219":130,"220":74,"221":49,"222":16,"223":157,"224":128,"225":220,"226":0,"227":193,"228":146,"229":74,"230":60,"231":99,"232":124,"233":19,"234":155,"235":153,"236":153,"237":25,"238":66,"239":222,"240":35,"241":72,"242":68,"243":7,"244":208,"245":180,"246":63,"247":32,"248":248,"249":26,"250":133,"251":167,"252":33,"253":203,"254":244,"255":193,"256":62,"257":0,"258":233,"259":135,"260":125,"261":10,"262":122,"263":55,"264":125,"265":104,"266":13,"267":200,"268":229,"269":124,"270":62,"271":255,"272":68,"273":183,"274":60,"275":126,"276":124,"277":17,"278":3,"279":169,"280":187,"281":192,"282":187,"283":73,"284":76,"285":20,"286":253,"287":5,"288":185,"289":31,"290":137,"291":68,"292":70,"293":211,"294":233,"295":116,"296":205,"297":169,"298":78,"299":185,"300":92,"301":142,"302":55,"303":26,"304":141,"305":107,"306":32,"307":119,"308":29,"309":178,"310":87,"311":196,"312":140,"313":128,"314":220,"315":45,"316":167,"317":120,"318":179,"319":79,"320":153,"321":24,"322":150,"323":239,"324":18,"325":246,"326":147,"327":126,"328":181,"329":32,"330":84,"331":130,"332":156,"333":197,"334":210,"335":44,"336":152,"337":193,"338":220,"339":250,"340":200,"341":229,"342":254,"343":155,"344":132,"345":100,"346":24,"347":131,"348":125,"349":55,"350":132,"351":220,"352":167,"353":110,"354":241,"355":244,"356":43,"357":17,"358":43,"359":22,"360":139,"361":105,"362":128,"363":114,"364":3,"365":71,"366":72,"367":42,"368":30,"369":143,"370":159,"371":72,"372":38,"373":147,"374":213,"375":86,"376":192,"377":214,"378":177,"379":197,"380":197,"381":197,"382":174,"383":90,"384":173,"385":246,"386":158,"387":228,"388":128,"389":81,"390":199,"391":120,"392":62,"393":151,"394":203,"395":149,"396":173,"397":113,"398":210,"399":14,"400":203,"401":142,"402":135,"403":30,"404":193,"405":56,"406":247,"407":212,"408":239,"409":142,"410":142,"411":142,"412":130,"413":95,"414":82,"415":196,"416":102,"417":14,"418":115,"419":137,"420":1,"421":114,"422":81,"423":104,"424":98,"425":186,"426":54,"427":79,"428":98,"429":115,"430":115,"431":115,"432":89,"433":0,"434":13,"435":18,"436":1,"437":87,"438":250,"439":32,"440":155,"441":205,"442":126,"443":113,"444":69,"445":243,"446":24,"447":96,"448":46,"449":49,"450":24,"451":70,"452":76,"453":98,"454":187,"455":165,"456":120,"457":18,"458":91,"459":91,"460":91,"461":59,"462":199,"463":100,"464":78,"465":127,"466":44,"467":22,"468":27,"469":117,"470":3,"471":82,"472":245,"473":19,"474":67,"475":44,"476":101,"477":72,"478":98,"479":59,"480":229,"481":122,"482":18,"483":67,"484":210,"485":0,"486":19,"487":113,"488":133,"489":111,"490":82,"491":169,"492":212,"493":79,"494":39,"495":16,"496":63,"497":62,"498":98,"499":16,"500":75,"501":228,"502":240,"503":198,"504":236,"505":216,"506":60,"507":137,"508":1,"509":228,"510":160,"511":200,"512":156,"513":118,"514":68,"515":8,"516":230,"517":148,"518":88,"519":18,"520":219,"521":134,"522":226,"523":74,"524":12,"525":132,"526":34,"527":75,"528":75,"529":75,"530":123,"531":48,"532":237,"533":221,"534":204,"535":194,"536":17,"537":255,"538":70,"539":223,"540":86,"541":8,"542":224,"543":190,"544":11,"545":38,"546":221,"547":172,"548":65,"549":76,"550":97,"551":27,"552":202,"553":118,"554":187,"555":192,"556":173,"557":225,"558":34,"559":70,"560":31,"561":34,"562":88,"563":127,"564":238,"565":25,"566":145,"567":219,"568":220,"569":193,"570":4,"571":240,"572":249,"573":122,"574":5,"575":183,"576":144,"577":231,"578":44,"579":213,"580":52,"581":99,"582":32,"583":211,"584":9,"585":121,"586":220,"587":110,"588":82,"589":36,"590":194,"591":154,"592":162,"593":118,"594":167,"595":141,"596":88,"597":165,"598":82,"599":233,"600":130,"601":51,"602":198,"603":129,"604":0,"605":109,"606":21,"607":87,"608":253,"609":142,"610":130,"611":220,"612":213,"613":0,"614":249,"615":76,"616":137,"617":9,"618":14,"619":33,"620":157,"621":93,"622":64,"623":16,"624":35,"625":13,"626":100,"627":248,"628":172,"629":60,"630":137,"631":101,"632":248,"633":72,"634":39,"635":182,"636":195,"637":81,"638":168,"639":183,"640":152,"641":129,"642":56,"643":237,"644":32,"645":173,"646":105,"647":41,"648":177,"649":193,"650":29,"651":31,"652":198,"653":10,"654":192,"655":99,"656":146,"657":20,"658":99,"659":69,"660":127,"661":76,"662":33,"663":207,"664":22,"665":34,"666":57,"667":52,"668":17,"669":235,"670":233,"671":233,"672":249,"673":43,"674":54,"675":161,"676":45,"677":161,"678":149,"679":3,"680":51,"681":243,"682":213,"683":58,"684":238,"685":228,"686":179,"687":198,"688":88,"689":109,"690":214,"691":38,"692":7,"693":250,"694":155,"695":136,"696":209,"697":1,"698":64,"699":253,"700":157,"701":138,"702":125,"703":213,"704":6,"705":192,"706":211,"707":214,"708":88,"709":39,"710":159,"711":53,"712":198,"713":106,"714":155,"715":107,"716":219,"717":136,"718":1,"719":80,"720":249,"721":45,"722":83,"723":2,"724":3,"725":240,"726":2,"727":222,"728":213,"729":174,"730":74,"731":155,"732":125,"733":250,"734":164,"735":173,"736":170,"737":205,"738":181,"739":157,"740":136,"741":77,"742":168,"743":2,"744":153,"745":227,"746":0,"747":122,"748":92,"749":218,"750":230,"751":190,"752":244,"753":169,"754":104,"755":228,"756":25,"757":181,"758":109,"759":196,"760":112,"761":165,"762":83,"763":0,"764":9,"765":122,"766":220,"767":85,"768":234,"769":187,"770":197,"771":172,"772":138,"773":218,"774":250,"775":184,"776":141,"777":24,"778":78,"779":212,"780":15,"781":140,"782":24,"783":204,"784":221,"785":80,"786":182,"787":193,"788":255,"789":82,"790":212,"791":118,"792":38,"793":70,"794":47,"795":166,"796":116,"797":24,"798":170,"799":157,"800":179,"801":198,"802":155,"803":243,"804":109,"805":157,"806":145,"807":248,"808":177,"809":205,"810":24,"811":253,"812":96,"813":94,"814":70,"815":224,"816":51,"817":115,"818":160,"819":66,"820":63,"821":143,"822":165,"823":208,"824":132,"825":28,"826":81,"827":136,"828":55,"829":66,"830":88,"831":139,"832":53,"833":13,"834":7,"835":58,"836":182,"837":135,"838":184,"839":28,"840":20,"841":239,"842":232,"843":31,"844":80,"845":232,"846":144,"847":244,"848":41,"849":232,"850":79,"851":34,"852":230,"853":176,"854":66,"855":172,"856":30,"857":2,"858":82,"859":159,"860":241,"861":13,"862":113,"863":44,"864":105,"865":249,"866":134,"867":112,"868":37,"869":198,"870":172,"871":82,"872":169,"873":212,"874":91,"875":175,"876":215,"877":249,"878":238,"879":196,"880":103,"881":232,"882":118,"883":180,"884":106,"885":52,"886":26,"887":237,"888":207,"889":100,"890":50,"891":21,"892":43,"893":184,"894":227,"895":82,"896":202,"897":32,"898":38,"899":224,"900":138,"901":6,"902":97,"903":87,"904":165,"905":111,"906":11,"907":117,"908":149,"909":216,"910":78,"911":164,"912":88,"913":163,"914":229,"915":140,"916":73,"917":18,"918":98,"919":230,"920":38,"921":97,"922":247,"923":74,"924":223,"925":102,"926":52,"927":151,"928":15,"929":31,"930":202,"931":5,"932":55,"933":82,"934":196,"935":110,"936":57,"937":99,"938":178,"939":56,"940":1,"941":18,"942":137,"943":4,"944":63,"945":249,"946":199,"947":225,"948":219,"949":204,"950":105,"951":229,"952":233,"953":27,"954":231,"955":158,"956":106,"957":69,"958":138,"959":117,"960":149,"961":102,"962":76,"963":18,"964":164,"965":22,"966":31,"967":191,"968":119,"969":208,"970":229,"971":55,"972":162,"973":234,"974":107,"975":19,"976":47,"977":134,"978":127,"979":172,"980":12,"981":91,"982":79,"983":31,"984":252,"985":142,"986":205,"987":55,"988":49,"989":137,"990":2,"991":130,"992":251,"993":80,"994":104,"995":0,"996":167,"997":182,"998":0,"999":225,"1000":215,"1001":53,"1002":255,"1003":72,"1004":209,"1005":95,"1006":199,"1007":209,"1008":95,"1009":65,"1010":127,"1011":25,"1012":154,"1013":127,"1014":37,"1015":76,"1016":160,"1017":63,"1018":101,"1019":190,"1020":121,"1021":74,"1022":140,"1023":182,"1024":233,"1025":173,"1026":252,"1027":227,"1028":174,"1029":109,"1030":164,"1031":253,"1032":22,"1033":250,"1034":7,"1035":195,"1036":1,"1037":181,"1038":72,"1039":49,"1040":32,"1041":229,"1042":123,"1043":0,"1044":0,"1045":0,"1046":0,"1047":73,"1048":69,"1049":78,"1050":68,"1051":174,"1052":66,"1053":96,"1054":130}

这是一张png的图片 。 他的MIME类型是 image/png       MIME类型参考

拿到了相应的MIME类型 和 二进制数据后，就可以开始转换文件了，先把对象转成数组，

在这里 我们需要了解一下 ArrayBuffer和  Unit8Array等数组类型，我们最终需要得到一个ArrayBuffer类型的二进制数组。

这里不能使用普通数组的原因是我们接下来需要将二进制数组转成Blob对象，而Blob构造函数明确要求：

   传入的第一个参数array 是一个由ArrayBuffer, ArrayBufferView, Blob, DOMString 等对象构成的 Array ，或者其他类似对象的混合体，它将会被放进 Blob.

相关代码：

// 首先将对象转换成普通数组 得到长度
var cacheArr = new Array();
    for (let i in two_obj){
        cacheArr[i] = two_obj[i];
    }
    var len = cacheArr.length;
// 构造ArrayBuffer 并通过Uint8Array的实例来对其修改 将普通的数组转成ArrayBuffer数组
    var buffer = new ArrayBuffer(len);
    var arr = new Uint8Array(buffer);

    for (var i = 0;i<len;i++){
        arr[i] = cacheArr[i];
    }

第一步完成后，下一步就是真正的转换了，首先把得到的二进制数组转成相应的Blob对象，然后由window.URL.createObjectURL将该对象转成一个链接，然后就可以通过创建一个a标签来下载相应的文件啦。

下载完成后记得用window.URL.revokeObjectURL释放这个链接。

相关代码：

       var data = new Blob([arr],{type:"image/png"});
        var downloadUrl = window.URL.createObjectURL(data);
        var result=document.getElementById("result");
        var anchor = document.createElement("a");
        anchor.href = downloadUrl;
        anchor.download = "fsdfds.png";
        anchor.click();
        window.URL.revokeObjectURL(data); 

总结一下， 具体的思路就是：

1.将二进制转成ArrayBuffer数组，方便Blob使用，

2.将得到的Blob对象，利用window.URL.createObjectURL()来创建一个链接指向它。

3.创建A标签元素 download属性指向该链接，通过点击来下载它。

4.释放创建的链接。

最后放上例子代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>

</head>
<body>
<script type="text/javascript">  

</script>
    <input type="button" value="下载文件" onclick="readAsBinaryString()" />
<div id="result" name="result"></div>
</body>
</html>
<script type="text/javascript">
    var two_obj = {"0":137,"1":80,"2":78,"3":71,"4":13,"5":10,"6":26,"7":10,"8":0,"9":0,"10":0,"11":13,"12":73,"13":72,"14":68,"15":82,"16":0,"17":0,"18":0,"19":38,"20":0,"21":0,"22":0,"23":38,"24":8,"25":6,"26":0,"27":0,"28":0,"29":168,"30":61,"31":233,"32":174,"33":0,"34":0,"35":0,"36":1,"37":115,"38":82,"39":71,"40":66,"41":0,"42":174,"43":206,"44":28,"45":233,"46":0,"47":0,"48":3,"49":217,"50":73,"51":68,"52":65,"53":84,"54":88,"55":9,"56":237,"57":88,"58":61,"59":104,"60":83,"61":81,"62":20,"63":206,"64":75,"65":155,"66":168,"67":196,"68":132,"69":42,"70":116,"71":113,"72":139,"73":161,"74":53,"75":33,"76":54,"77":17,"78":28,"79":170,"80":110,"81":130,"82":32,"83":88,"84":12,"85":85,"86":220,"87":28,"88":237,"89":228,"90":32,"91":34,"92":14,"93":106,"94":93,"95":181,"96":14,"97":90,"98":138,"99":131,"100":96,"101":81,"102":55,"103":87,"104":193,"105":150,"106":58,"107":137,"108":14,"109":130,"110":216,"111":193,"112":161,"113":169,"114":37,"115":49,"116":181,"117":20,"118":44,"119":20,"120":116,"121":168,"122":145,"123":40,"124":104,"125":210,"126":31,"127":191,"128":239,"129":113,"130":239,"131":243,"132":229,"133":253,"134":228,"135":221,"136":247,"137":218,"138":102,"139":234,"140":133,"141":147,"142":115,"143":207,"144":185,"145":231,"146":124,"147":231,"148":123,"149":247,"150":231,"151":253,"152":36,"153":20,"154":218,"155":105,"156":59,"157":51,"158":96,"159":159,"160":129,"161":249,"162":249,"163":249,"164":93,"165":20,"166":251,"167":136,"168":127,"169":143,"170":230,"171":63,"172":229,"173":127,"174":198,"175":236,"176":236,"177":108,"178":110,"179":125,"180":125,"181":253,"182":188,"183":166,"184":105,"185":103,"186":224,"187":77,"188":109,"189":108,"190":108,"191":236,"192":231,"193":40,"194":236,"195":21,"196":168,"197":5,"198":216,"199":175,"200":194,"201":225,"202":240,"203":139,"204":190,"205":190,"206":190,"207":34,"208":253,"209":126,"210":90,"211":32,"212":98,"213":32,"214":148,"215":65,"216":209,"217":123,"218":144,"219":130,"220":74,"221":49,"222":16,"223":157,"224":128,"225":220,"226":0,"227":193,"228":146,"229":74,"230":60,"231":99,"232":124,"233":19,"234":155,"235":153,"236":153,"237":25,"238":66,"239":222,"240":35,"241":72,"242":68,"243":7,"244":208,"245":180,"246":63,"247":32,"248":248,"249":26,"250":133,"251":167,"252":33,"253":203,"254":244,"255":193,"256":62,"257":0,"258":233,"259":135,"260":125,"261":10,"262":122,"263":55,"264":125,"265":104,"266":13,"267":200,"268":229,"269":124,"270":62,"271":255,"272":68,"273":183,"274":60,"275":126,"276":124,"277":17,"278":3,"279":169,"280":187,"281":192,"282":187,"283":73,"284":76,"285":20,"286":253,"287":5,"288":185,"289":31,"290":137,"291":68,"292":70,"293":211,"294":233,"295":116,"296":205,"297":169,"298":78,"299":185,"300":92,"301":142,"302":55,"303":26,"304":141,"305":107,"306":32,"307":119,"308":29,"309":178,"310":87,"311":196,"312":140,"313":128,"314":220,"315":45,"316":167,"317":120,"318":179,"319":79,"320":153,"321":24,"322":150,"323":239,"324":18,"325":246,"326":147,"327":126,"328":181,"329":32,"330":84,"331":130,"332":156,"333":197,"334":210,"335":44,"336":152,"337":193,"338":220,"339":250,"340":200,"341":229,"342":254,"343":155,"344":132,"345":100,"346":24,"347":131,"348":125,"349":55,"350":132,"351":220,"352":167,"353":110,"354":241,"355":244,"356":43,"357":17,"358":43,"359":22,"360":139,"361":105,"362":128,"363":114,"364":3,"365":71,"366":72,"367":42,"368":30,"369":143,"370":159,"371":72,"372":38,"373":147,"374":213,"375":86,"376":192,"377":214,"378":177,"379":197,"380":197,"381":197,"382":174,"383":90,"384":173,"385":246,"386":158,"387":228,"388":128,"389":81,"390":199,"391":120,"392":62,"393":151,"394":203,"395":149,"396":173,"397":113,"398":210,"399":14,"400":203,"401":142,"402":135,"403":30,"404":193,"405":56,"406":247,"407":212,"408":239,"409":142,"410":142,"411":142,"412":130,"413":95,"414":82,"415":196,"416":102,"417":14,"418":115,"419":137,"420":1,"421":114,"422":81,"423":104,"424":98,"425":186,"426":54,"427":79,"428":98,"429":115,"430":115,"431":115,"432":89,"433":0,"434":13,"435":18,"436":1,"437":87,"438":250,"439":32,"440":155,"441":205,"442":126,"443":113,"444":69,"445":243,"446":24,"447":96,"448":46,"449":49,"450":24,"451":70,"452":76,"453":98,"454":187,"455":165,"456":120,"457":18,"458":91,"459":91,"460":91,"461":59,"462":199,"463":100,"464":78,"465":127,"466":44,"467":22,"468":27,"469":117,"470":3,"471":82,"472":245,"473":19,"474":67,"475":44,"476":101,"477":72,"478":98,"479":59,"480":229,"481":122,"482":18,"483":67,"484":210,"485":0,"486":19,"487":113,"488":133,"489":111,"490":82,"491":169,"492":212,"493":79,"494":39,"495":16,"496":63,"497":62,"498":98,"499":16,"500":75,"501":228,"502":240,"503":198,"504":236,"505":216,"506":60,"507":137,"508":1,"509":228,"510":160,"511":200,"512":156,"513":118,"514":68,"515":8,"516":230,"517":148,"518":88,"519":18,"520":219,"521":134,"522":226,"523":74,"524":12,"525":132,"526":34,"527":75,"528":75,"529":75,"530":123,"531":48,"532":237,"533":221,"534":204,"535":194,"536":17,"537":255,"538":70,"539":223,"540":86,"541":8,"542":224,"543":190,"544":11,"545":38,"546":221,"547":172,"548":65,"549":76,"550":97,"551":27,"552":202,"553":118,"554":187,"555":192,"556":173,"557":225,"558":34,"559":70,"560":31,"561":34,"562":88,"563":127,"564":238,"565":25,"566":145,"567":219,"568":220,"569":193,"570":4,"571":240,"572":249,"573":122,"574":5,"575":183,"576":144,"577":231,"578":44,"579":213,"580":52,"581":99,"582":32,"583":211,"584":9,"585":121,"586":220,"587":110,"588":82,"589":36,"590":194,"591":154,"592":162,"593":118,"594":167,"595":141,"596":88,"597":165,"598":82,"599":233,"600":130,"601":51,"602":198,"603":129,"604":0,"605":109,"606":21,"607":87,"608":253,"609":142,"610":130,"611":220,"612":213,"613":0,"614":249,"615":76,"616":137,"617":9,"618":14,"619":33,"620":157,"621":93,"622":64,"623":16,"624":35,"625":13,"626":100,"627":248,"628":172,"629":60,"630":137,"631":101,"632":248,"633":72,"634":39,"635":182,"636":195,"637":81,"638":168,"639":183,"640":152,"641":129,"642":56,"643":237,"644":32,"645":173,"646":105,"647":41,"648":177,"649":193,"650":29,"651":31,"652":198,"653":10,"654":192,"655":99,"656":146,"657":20,"658":99,"659":69,"660":127,"661":76,"662":33,"663":207,"664":22,"665":34,"666":57,"667":52,"668":17,"669":235,"670":233,"671":233,"672":249,"673":43,"674":54,"675":161,"676":45,"677":161,"678":149,"679":3,"680":51,"681":243,"682":213,"683":58,"684":238,"685":228,"686":179,"687":198,"688":88,"689":109,"690":214,"691":38,"692":7,"693":250,"694":155,"695":136,"696":209,"697":1,"698":64,"699":253,"700":157,"701":138,"702":125,"703":213,"704":6,"705":192,"706":211,"707":214,"708":88,"709":39,"710":159,"711":53,"712":198,"713":106,"714":155,"715":107,"716":219,"717":136,"718":1,"719":80,"720":249,"721":45,"722":83,"723":2,"724":3,"725":240,"726":2,"727":222,"728":213,"729":174,"730":74,"731":155,"732":125,"733":250,"734":164,"735":173,"736":170,"737":205,"738":181,"739":157,"740":136,"741":77,"742":168,"743":2,"744":153,"745":227,"746":0,"747":122,"748":92,"749":218,"750":230,"751":190,"752":244,"753":169,"754":104,"755":228,"756":25,"757":181,"758":109,"759":196,"760":112,"761":165,"762":83,"763":0,"764":9,"765":122,"766":220,"767":85,"768":234,"769":187,"770":197,"771":172,"772":138,"773":218,"774":250,"775":184,"776":141,"777":24,"778":78,"779":212,"780":15,"781":140,"782":24,"783":204,"784":221,"785":80,"786":182,"787":193,"788":255,"789":82,"790":212,"791":118,"792":38,"793":70,"794":47,"795":166,"796":116,"797":24,"798":170,"799":157,"800":179,"801":198,"802":155,"803":243,"804":109,"805":157,"806":145,"807":248,"808":177,"809":205,"810":24,"811":253,"812":96,"813":94,"814":70,"815":224,"816":51,"817":115,"818":160,"819":66,"820":63,"821":143,"822":165,"823":208,"824":132,"825":28,"826":81,"827":136,"828":55,"829":66,"830":88,"831":139,"832":53,"833":13,"834":7,"835":58,"836":182,"837":135,"838":184,"839":28,"840":20,"841":239,"842":232,"843":31,"844":80,"845":232,"846":144,"847":244,"848":41,"849":232,"850":79,"851":34,"852":230,"853":176,"854":66,"855":172,"856":30,"857":2,"858":82,"859":159,"860":241,"861":13,"862":113,"863":44,"864":105,"865":249,"866":134,"867":112,"868":37,"869":198,"870":172,"871":82,"872":169,"873":212,"874":91,"875":175,"876":215,"877":249,"878":238,"879":196,"880":103,"881":232,"882":118,"883":180,"884":106,"885":52,"886":26,"887":237,"888":207,"889":100,"890":50,"891":21,"892":43,"893":184,"894":227,"895":82,"896":202,"897":32,"898":38,"899":224,"900":138,"901":6,"902":97,"903":87,"904":165,"905":111,"906":11,"907":117,"908":149,"909":216,"910":78,"911":164,"912":88,"913":163,"914":229,"915":140,"916":73,"917":18,"918":98,"919":230,"920":38,"921":97,"922":247,"923":74,"924":223,"925":102,"926":52,"927":151,"928":15,"929":31,"930":202,"931":5,"932":55,"933":82,"934":196,"935":110,"936":57,"937":99,"938":178,"939":56,"940":1,"941":18,"942":137,"943":4,"944":63,"945":249,"946":199,"947":225,"948":219,"949":204,"950":105,"951":229,"952":233,"953":27,"954":231,"955":158,"956":106,"957":69,"958":138,"959":117,"960":149,"961":102,"962":76,"963":18,"964":164,"965":22,"966":31,"967":191,"968":119,"969":208,"970":229,"971":55,"972":162,"973":234,"974":107,"975":19,"976":47,"977":134,"978":127,"979":172,"980":12,"981":91,"982":79,"983":31,"984":252,"985":142,"986":205,"987":55,"988":49,"989":137,"990":2,"991":130,"992":251,"993":80,"994":104,"995":0,"996":167,"997":182,"998":0,"999":225,"1000":215,"1001":53,"1002":255,"1003":72,"1004":209,"1005":95,"1006":199,"1007":209,"1008":95,"1009":65,"1010":127,"1011":25,"1012":154,"1013":127,"1014":37,"1015":76,"1016":160,"1017":63,"1018":101,"1019":190,"1020":121,"1021":74,"1022":140,"1023":182,"1024":233,"1025":173,"1026":252,"1027":227,"1028":174,"1029":109,"1030":164,"1031":253,"1032":22,"1033":250,"1034":7,"1035":195,"1036":1,"1037":181,"1038":72,"1039":49,"1040":32,"1041":229,"1042":123,"1043":0,"1044":0,"1045":0,"1046":0,"1047":73,"1048":69,"1049":78,"1050":68,"1051":174,"1052":66,"1053":96,"1054":130}
    // 首先将对象转换成普通数组 得到长度
    var cacheArr = new Array();
    for (let i in two_obj){
        cacheArr[i] = two_obj[i];
    }
    var len = cacheArr.length;
    // 构造ArrayBuffer 并通过Uint8Array的实例来对其修改 将普通的数组转成ArrayBuffer数组
    var buffer = new ArrayBuffer(len);
    var arr = new Uint8Array(buffer);

    for (var i = 0;i<len;i++){
        arr[i] = cacheArr[i];
    }

    function readAsBinaryString(){
        var data = new Blob([arr],{type:"image/png"});
        var downloadUrl = window.URL.createObjectURL(data);
        var result=document.getElementById("result");
        var anchor = document.createElement("a");
        anchor.href = downloadUrl;
        anchor.download = "fsdfds.png";
        anchor.click();
        window.URL.revokeObjectURL(data);
}
</script>