php base64图片上传

<img src="{$list.img}" id="input_img" class="max-width:200px;">
<input type="hidden"  name="img" id="input_imgName" value="">
<input type="hidden" id="oldImg" value="{$list.img}">

<input type="file" id="file_img"/>

<script>
function readFile(){
var file = this.files[0];
if(!/image\/\w+/.test(file.type)){
alert("只能上传图片");
return false;

var reader = new FileReader();
reader.readAsDataURL(file);
reader.onload = function(e){
var postData = {
'result':this.result,
'oldImg':$('#oldImg').val()
}
$.post("{:U('Banner/saveBase64Img')}",postData,function(data){
console.log(data);
$('#input_img').attr('src','/'+data.data).css({'max-width':'200px'});
$('#input_imgName').val('/'+data.data);
img_area.style.maxWidth = "200px";
});
}
}

$(function(){
if ( typeof(FileReader) === 'undefined' ){
result = "请使用现代浏览器操作";
alert(result);
$('#input_img').attr('disabled','disabled');
} else {
$('#input_img').addEventListener( 'change',readFile,false );
}
});

public function saveBase64Img(){
$oldImg = I('oldImg');
if(empty($oldImg)){
if(file_exists($file)){
if (unlink($file)){
return true;
}
}
}
$base64_image_content = I('result');
header('Content-type:text/html;charset=utf-8');
//匹配出图片的格式
if (preg_match('/^(data:\s*image\/(\w+);base64,)/', $base64_image_content, $result)){
$type = $result[2];
$new_file = "./Public/Uploads/".time().".{$type}";
if (file_put_contents($new_file, base64_decode(str_replace($result[1], '', $base64_image_content)))){
$this->ajaxReturn(array('code'=>2000,'msg'=>'upload img ok','data'=>$new_file));
}
}
}