php做图片上传功能

今天来做一个图片上传功能的插件，首先做一个html文件：text.php

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>

<body>
<h1>文件上传</h1><div id="divPreview">        <img id="imgHeadPhoto" src="noperson.jpg" style="width: 160px; height: 170px; border: solid 1px #d2e2e2;"            alt="" /></div>
<!--enctype 属性规定在发送到服务器之前应该如何对表单数据进行编码,"multipart/form-data"在使用包含文件上传控件的表单时，必须使用该值。-->
<form action="upload.php" method="post" enctype="multipart/form-data">
<!--file定义输入字段和 "浏览"按钮，供文件上传。-->
    <input type="file" name="file" onchange="PreviewImage(this,'imgHeadPhoto','divPreview');" size="20" />
    <input  type="submit" value="上传"/>

</form>
</body><script type="text/javascript">        //js本地图片预览，兼容ie[6-9]、火狐、Chrome17+、Opera11+、Maxthon3        function PreviewImage(fileObj, imgPreviewId, divPreviewId) {            var allowExtention = ".jpg,.bmp,.gif,.png"; //允许上传文件的后缀名document.getElementById("hfAllowPicSuffix").value;            var extention = fileObj.value.substring(fileObj.value.lastIndexOf(".") + 1).toLowerCase();            var browserVersion = window.navigator.userAgent.toUpperCase();            if (allowExtention.indexOf(extention) > -1) {                if (fileObj.files) {//HTML5实现预览，兼容chrome、火狐7+等                    if (window.FileReader) {                        var reader = new FileReader();                        reader.onload = function (e) {                            document.getElementById(imgPreviewId).setAttribute("src", e.target.result);                        }                        reader.readAsDataURL(fileObj.files[0]);                    } else if (browserVersion.indexOf("SAFARI") > -1) {                        alert("不支持Safari6.0以下浏览器的图片预览!");                    }                } else if (browserVersion.indexOf("MSIE") > -1) {                    if (browserVersion.indexOf("MSIE 6") > -1) {//ie6                        document.getElementById(imgPreviewId).setAttribute("src", fileObj.value);                    } else {//ie[7-9]                        fileObj.select();                        if (browserVersion.indexOf("MSIE 9") > -1)                            fileObj.blur(); //不加上document.selection.createRange().text在ie9会拒绝访问                        var newPreview = document.getElementById(divPreviewId + "New");                        if (newPreview == null) {                            newPreview = document.createElement("div");                            newPreview.setAttribute("id", divPreviewId + "New");                            newPreview.style.width = document.getElementById(imgPreviewId).width + "px";                            newPreview.style.height = document.getElementById(imgPreviewId).height + "px";                            newPreview.style.border = "solid 1px #d2e2e2";                        }                        newPreview.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='scale',src='" + document.selection.createRange().text + "')";                        var tempDivPreview = document.getElementById(divPreviewId);                        tempDivPreview.parentNode.insertBefore(newPreview, tempDivPreview);                        tempDivPreview.style.display = "none";                    }                } else if (browserVersion.indexOf("FIREFOX") > -1) {//firefox                    var firefoxVersion = parseFloat(browserVersion.toLowerCase().match(/firefox\/([\d.]+)/)[1]);                    if (firefoxVersion < 7) {//firefox7以下版本                        document.getElementById(imgPreviewId).setAttribute("src", fileObj.files[0].getAsDataURL());                    } else {//firefox7.0+                                            document.getElementById(imgPreviewId).setAttribute("src", window.URL.createObjectURL(fileObj.files[0]));                    }                } else {                    document.getElementById(imgPreviewId).setAttribute("src", fileObj.value);                }            } else {                alert("仅支持" + allowExtention + "为后缀名的文件!");                fileObj.value = ""; //清空选中文件                if (browserVersion.indexOf("MSIE") > -1) {                    fileObj.select();                    document.selection.clear();                }                fileObj.outerHTML = fileObj.outerHTML;            }            return fileObj.value;    //返回路径        }    </script>
</html>

做完后的效果：

这样可以点击浏览选择图片，然后上传，现在我们再做怎样把选择的图片传到我们新建的img文件里来，在做一个php处理页面：upload.php

<?php
//var_dump($_FILES["file"]);
//array(5) { ["name"]=> string(17) "56e79ea2e1418.jpg" ["type"]=> string(10) "image/jpeg" ["tmp_name"]=> string(43) "C:\Users\asus\AppData\Local\Temp\phpD07.tmp" ["error"]=> int(0) ["size"]=> int(454445) } 
//1.限制文件的类型，防止注入php或其他文件，提升安全
//2.限制文件的大小，减少内存压力
//3.防止文件名重复，提升用户体验
    //方法一：  修改文件名    一般为:时间戳+随机数+用户名
    // 方法二:建文件夹
    
//4.保存文件

//判断上传的文件是否出错,是的话，返回错误
if($_FILES["file"]["error"])
{
    echo $_FILES["file"]["error"];    
}
else
{
    //没有出错
    //加限制条件
    //判断上传文件类型为png或jpg且大小不超过1024000B
    if(($_FILES["file"]["type"]=="image/png"||$_FILES["file"]["type"]=="image/jpeg")&&$_FILES["file"]["size"]<1024000)
    {
            //防止文件名重复
            $filename ="./img/".time().$_FILES["file"]["name"];
            //转码，把utf-8转成gb2312,返回转换后的字符串， 或者在失败时返回 FALSE。
            $filename =iconv("UTF-8","gb2312",$filename);
             //检查文件或目录是否存在
            if(file_exists($filename))
            {
                echo"该文件已存在";
            }
            else
            {  
                //保存文件,   move_uploaded_file 将上传的文件移动到新位置  
                move_uploaded_file($_FILES["file"]["tmp_name"],$filename);//将临时地址移动到指定地址    
            }        
    }
    else
    {
        echo"文件类型不对";
    }
}

现在我们看看效果怎么样：