直接上代码，要点就是把base64转成Blob，添加到FormData传递给后台程序，跟选择图片文件上传时一样的了。

 

var dataurl = canvas.toDataURL('image/png'); //base64图片数据var arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1],bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);while(n--){    u8arr[n] = bstr.charCodeAt(n);}var obj = new Blob([u8arr], {type:mime});var fd = new FormData();fd.append("upfile", obj,"image.png");$.ajax({    url: "/file/upfile",    type: "POST",    processData: false,    contentType: false,    data: fd,    success: function (data) {        console.log(data);    }});//canvas保存图片到本地 (function(t){    var dlLink = t || document.createElement("a");    if(!t){        dlLink.id='dlLink';        dlLink.download = '文件名';         document.body.appendChild(dlLink);    }    dlLink.href = dataurl;    dlLink.click();})(document.querySelector("#dlLink"));