jquery+php实现ajax单个上传

HTML部分 

<script type="text/javascript" src="jquery.min.js"></script>
<script type="text/javascript" src="jquery.form.js"></script>  
<div class="btn">
     <span>添加附件</span>
     <input id="fileupload" type="file" name="mypic">
</div>
<div class="progress">
    <span class="bar"></span><span class="percent">0%</span >
</div>
<div class="files"></div>
<div id="showimg"></div> 

CSS部分 

.btn{position: relative;overflow: hidden;margin-right: 4px;display:inline-block;
*display:inline;padding:4px 10px 4px;font-size:14px;line-height:18px;
*line-height:20px;color:#fff;
text-align:center;vertical-align:middle;cursor:pointer;background:#5bb75b;
border:1px solid #cccccc;border-color:#e6e6e6 #e6e6e6 #bfbfbf;
border-bottom-color:#b3b3b3;-webkit-border-radius:4px;
-moz-border-radius:4px;border-radius:4px;}
.btn input{position: absolute;top: 0; right: 0;margin: 0;border:solid transparent;
opacity: 0;filter:alpha(opacity=0); cursor: pointer;}
.progress{position:relative; margin-left:100px; margin-top:-24px;  
width:200px;padding: 1px; border-radius:3px; display:none}
.bar {background-color: green; display:block; width:0%; height:20px;  
border-radius:3px; }
.percent{position:absolute; height:20px; display:inline-block;  
top:3px; left:2%; color:#fff }
.files{height:22px; line-height:22px; margin:10px 0}
.delimg{margin-left:20px; color:#090; cursor:pointer} 

js部分 

$(function () {
    var bar = $('.bar');
    var percent = $('.percent');
    var showimg = $('#showimg');
    var progress = $(".progress");
    var files = $(".files");
    var btn = $(".btn span");
    $("#fileupload").wrap("<form id='myupload' action='action.php'  
    method='post' enctype='multipart/form-data'></form>");
    $("#fileupload").change(function(){ //选择文件
        $("#myupload").ajaxSubmit({
            dataType:  'json', //数据格式为json
            beforeSend: function() { //开始上传
                showimg.empty(); //清空显示的图片
                progress.show(); //显示进度条
                var percentVal = '0%'; //开始进度为0%
                bar.width(percentVal); //进度条的宽度
                percent.html(percentVal); //显示进度为0%
                btn.html("上传中..."); //上传按钮显示上传中
            },
            uploadProgress: function(event, position, total, percentComplete) {
                var percentVal = percentComplete + '%'; //获得进度
                bar.width(percentVal); //上传进度条宽度变宽
                percent.html(percentVal); //显示上传进度百分比
            },
            success: function(data) { //成功
                //获得后台返回的json数据，显示文件名，大小，以及删除按钮
                files.html("<b>"+data.name+"("+data.size+"k)</b>  
                <span class='delimg' rel='"+data.pic+"'>删除</span>");
                //显示上传后的图片
                var img = "http://demo./upload/files/"+data.pic;
                showimg.html("<img src='"+img+"'>");
                btn.html("添加附件"); //上传按钮还原
            },
            error:function(xhr){ //上传失败
                btn.html("上传失败");
                bar.width('0');
                files.html(xhr.responseText); //返回失败信息
            }
        });
    });
    ...
});

//接下来，文件上传完成，如果用户想删除上传的文件，可以写个ajax post请求来完成删除操作。

$(function () {
    ...接上面的代码
    $(".delimg").live('click',function(){
        var pic = $(this).attr("rel");
        $.post("action.php?act=delimg",{imagename:pic},function(msg){
            if(msg==1){
                files.html("删除成功.");
                showimg.empty(); //清空图片
                progress.hide(); //隐藏进度条
            }else{
                alert(msg);
            }
        });
    });
}); 

PHP部分 

action.php中需要处理图片上传以及删除图片。图片上传时需要验证格式和大小，然后通过move_uploaded_file()方法上传图片，最后返回json格式的数据。删除图片时使用unlink()即可完成删除操作。 

$action = $_GET['act'];
if($action=='delimg'){ //删除图片
    $filename = $_POST['imagename'];
    if(!empty($filename)){
        unlink('files/'.$filename);
        echo '1';
    }else{
        echo '删除失败.';
    }
}else{ //上传图片
    $picname = $_FILES['mypic']['name'];
    $picsize = $_FILES['mypic']['size'];
    if ($picname != "") {
        if ($picsize > 512000) { //限制上传大小
            echo '图片大小不能超过500k';
            exit;
        }
        $type = strstr($picname, '.'); //限制上传格式
        if ($type != ".gif" && $type != ".jpg") {
            echo '图片格式不对！';
            exit;
        }
        $rand = rand(100, 999);
        $pics = date("YmdHis") . $rand . $type; //命名图片名称
        //上传路径
        $pic_path = "files/". $pics;
        move_uploaded_file($_FILES['mypic']['tmp_name'], $pic_path);
    }
    $size = round($picsize/1024,2); //转换成kb
    $arr = array(
        'name'=>$picname,
        'pic'=>$pics,
        'size'=>$size
    );
    echo json_encode($arr); //输出json数据
}

本文借助了jquery form插件来完成单文