图片上传

<input id="file-input" type="file"  class="file" accept="image/jpeg,image/gif">
<img id="img" class="file-preview-image" src="">

<script>
$(function(){

        $("#file-input").change(function () {
           var url="http://127.0.0.6/index.php/service/image/?action=upload";
            uploadImg(url,this);
        });  

});
function readURL(input, tmpimg) {   
    if (input.files && input.files[0]) {  
        var reader = new FileReader();  
        reader.onload = function (e) {  
            if (!/image/.test(e.target.result)) {  
                alert('请上传图片格式...');  
                return false;   
            }  
            tmpimg.attr('src', e.target.result);  
        }  
        reader.readAsDataURL(input.files[0]);  
    }  
}  
function uploadImg(url,e){
            
    var file = e.files[0];  　
    $("#img-div").before(str);
    var $img = $("#img"); 
    readURL(e, $img);
    var formData = new FormData();  
    formData.append('picture', file); 
    $.ajax({  
        type: "POST", //必须用post  
        url: url ,  
        crossDomain: true,  
        jsonp: "jsoncallback",  
        data: formData,  
        contentType: false, //必须  
        processData: false,  
        success: function (data) {  
                ……    
        },
        error:function(){
            ……
        }
    });  
}
</script>

 如果要上传的url是跨域的，请在服务端加上

header("Access-Control-Allow-Origin:*");
header('Access-Control-Allow-Credentials:true');