我什么都不说，上代码：
<!DOCTYPE html><html><head><title>pc和手机端的图片上传处理</title><meta charset="utf-8" /><meta name="viewport" content="width=device-width" /></head><body><p>选择:</p><p><input type="file" accept="image/*" id="upload" name="upload"></p><div><button id="surebtn">确定上传</button></div><p>图片预览：</p><p id="preview"></p><script type="text/javascript">var upload = document.getElementById('upload'),preview = document.getElementById('preview'),surebtn = document.getElementById('surebtn'),imgurl = '';upload.addEventListener('change',handleFile,false);surebtn.addEventListener('click',upLoadFile,false);function handleFile(){window.URL = window.URL || window.webkitURL;var sUserAgent= navigator.userAgent.toLowerCase();var selected_file = upload.files[0];if(sUserAgent.match(/android/i) == "android"){ var img = new Image(); img.src = window.URL.createObjectURL(selected_file); preview.innerHTML = ''; preview.appendChild(img); var reader = new FileReader(); reader.onload = function(e) { imgurl = e.target.result; }; reader.readAsDataURL(selected_file);}else{//判断文件类型是否为图片 var imageType = /image.*/; if (!selected_file.type.match(imageType)) { return false; } var img = document.createElement('img'); img.file = selected_file; preview.innerHTML = ''; preview.appendChild(img); img.onload = function(){ imgurl = img.src; } var reader = new FileReader(); reader.onload = function(e) { img.src = e.target.result; }; reader.readAsDataURL(selected_file);}}function upLoadFile(){var start = imgurl.indexOf(',')+1;dataurl = imgurl.substr(start);var xmlhttp = new XMLHttpRequest();xmlhttp.open('post','todo.php',true);xmlhttp.setRequestHeader('Content-Type','application/x-www-form-urlencoded;charset=utf-8');xmlhttp.setRequestHeader('X_Requested-With','XMLHttpRequest');xmlhttp.send('dataurl='+encodeURIComponent(dataurl));xmlhttp.onreadystatechange=function(){if (xmlhttp.readyState==4 && xmlhttp.status==200){console.log(xmlhttp.responseText)}}}</script></body></html>
我已经传到了github上，地址是：https://github.com/fonglezen/mbUploadImg
主要是解决某些浏览器存在base64编码显示不出图片来，而是blob二进制编码的问题。
预览网址：http://www.fonglezen.com/project/mbUploadImg/