先粘上以下插件，在别的图片上传功能说不定各位能用的上。

1、jQuery File Upload

Demo地址：http://blueimp.github.io/jQuery-File-Upload/
优点是使用jquery进行图片的异步上传，可控性好，可根据自己的需求任意定制；
缺点是在IE9等一些浏览器中，不支持图片预览，图片选择框中不支持多文件选择（这点是我抛弃它的原因）；

2、CFUpdate

Demo地址：http://www.access2008.cn/update/
优点：使用js+flash实现，兼容所有浏览器，优点界面效果还可以，支持批量上传、支持预览、进度条、删除等功能，作为图片的上传控件非常好用；
缺点：定制型插件，只能修改颜色，样式已经固定死了；

3、SWFUpload

下载地址：http://code.google.com/p/swfupload/
中文文档帮助地址：http://www.phptogether.com/swfuploadoc/#uploadError
本文所使用的就是此插件，使用flash+jquery实现，可以更改按钮及各种样式；监听事件也很全。

以下贴出源码及设计思路，主要功能点包括：
1、图片的上传预览（先将图片上传至服务器，然后再返回地址预览，目前抛开html5比较靠谱的预览方式）
2、缩略图的产生（等比例缩放后再截取中间区域作为缩略图，类似QQ空间的做法，不过貌似QQ空间加入了人脸识别的功能）

以下是此次实现的功能截图：
 
1、Thumbnail.cs
代码如下:

public class Thumbnial 
{ 
/// <summary> 
/// 生成缩略图 
/// </summary> 
/// <param name="imgSource">原图片</param> 
/// <param name="newWidth">缩略图宽度</param> 
/// <param name="newHeight">缩略图高度</param> 
/// <param name="isCut">是否裁剪（以中心点）</param> 
/// <returns></returns> 
public static Image GetThumbnail(System.Drawing.Image imgSource, int newWidth, int newHeight, bool isCut) 
{ 
int rWidth = 0; // 等比例缩放后的宽度 
int rHeight = 0; // 等比例缩放后的高度 
int sWidth = imgSource.Width; // 原图片宽度 
int sHeight = imgSource.Height; // 原图片高度 
double wScale = (double)sWidth / newWidth; // 宽比例 
double hScale = (double)sHeight / newHeight; // 高比例 
double scale = wScale < hScale ? wScale : hScale; 
rWidth = (int)Math.Floor(sWidth / scale); 
rHeight = (int)Math.Floor(sHeight / scale); 
Bitmap thumbnail = new Bitmap(rWidth, rHeight); 
try 
{ 
// 如果是截取原图，并且原图比例小于所要截取的矩形框，那么保留原图 
if (!isCut && scale <= 1) 
{ 
return imgSource; 
} 
using (Graphics tGraphic = Graphics.FromImage(thumbnail)) 
{ 
tGraphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; /* new way */ 
Rectangle rect = new Rectangle(0, 0, rWidth, rHeight); 
Rectangle rectSrc = new Rectangle(0, 0, sWidth, sHeight); 
tGraphic.DrawImage(imgSource, rect, rectSrc, GraphicsUnit.Pixel); 
} 
if (!isCut) 
{ 
return thumbnail; 
} 
else 
{ 
int xMove = 0; // 向右偏移（裁剪） 
int yMove = 0; // 向下偏移（裁剪） 
xMove = (rWidth - newWidth) / 2; 
yMove = (rHeight - newHeight) / 2; 
Bitmap final_image = new Bitmap(newWidth, newHeight); 
using (Graphics fGraphic = Graphics.FromImage(final_image)) 
{ 
fGraphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; /* new way */ 
Rectangle rect1 = new Rectangle(0, 0, newWidth, newHeight); 
Rectangle rectSrc1 = new Rectangle(xMove, yMove, newWidth, newHeight); 
fGraphic.DrawImage(thumbnail, rect1, rectSrc1, GraphicsUnit.Pixel); 
} 
thumbnail.Dispose(); 
return final_image; 
} 
} 
catch (Exception e) 
{ 
return new Bitmap(newWidth, newHeight); 
} 
} 
} 
 
2、图片上传处理程序Upload.ashx 
 代码如下:

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.Drawing; 
namespace Mood 
{ 
/// <summary> 
/// Upload 的摘要说明 
/// </summary> 
public class Upload : IHttpHandler 
{ 
Image thumbnail; 
public void ProcessRequest(HttpContext context) 
{ 
context.Response.ContentType = "text/plain"; 
try 
{ 
string id = System.Guid.NewGuid().ToString(); 
HttpPostedFile jpeg_image_upload = context.Request.Files["Filedata"]; 
Image original_image = System.Drawing.Image.FromStream(jpeg_image_upload.InputStream); 
original_image.Save(System.Web.HttpContext.Current.Server.MapPath("~/Files/" + id + ".jpg")); 
int target_width = 200; 
int target_height = 150; 
string path = "Files/Files200/" + id + ".jpg"; 
string saveThumbnailPath = System.Web.HttpContext.Current.Server.MapPath("~/" + path); 
thumbnail = Thumbnial.GetThumbnail(original_image, target_width, target_height, true); 
thumbnail.Save(saveThumbnailPath); 
context.Response.Write(path); 
} 
catch (Exception e) 
{ 
// If any kind of error occurs return a 500 Internal Server error 
context.Response.StatusCode = 500; 
context.Response.Write("上传过程中出现错误!"); 
} 
finally 
{ 
if (thumbnail != null) 
{ 
thumbnail.Dispose(); 
} 
} 
} 
public bool IsReusable 
{ 
get 
{ 
return false; 
} 
} 
} 
} 
 
3、前台界面Mood.aspx 
 代码如下:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Mood.aspx.cs" Inherits="Mood.Mood" %> 
<!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 runat="server"> 
<script src="SwfUpload/swfupload.js" type="text/javascript"></script> 
<script src="jquery-1.7.1.js" type="text/javascript"></script> 
<link href="Style/Mood.css" rel="stylesheet" type="text/css" /> 
<title></title> 
<script type="text/javascript"> 
$().ready(function () { 
SetSwf(); 
$("#btnReply").click(function () { 
$("#divImgs").hide(); 
}); 
}); 
var swfu; 
function SetSwf() { 
swfu = new SWFUpload({ 
// Backend Settings 
upload_url: "Upload.ashx", 
// File Upload Settings 
file_size_limit: "20 MB", 
file_types: "*.jpg;*.png;*jpeg;*bmp", 
file_types_description: "JPG;PNG;JPEG;BMP", 
file_upload_limit: "0", // Zero means unlimited 
file_queue_error_handler: fileQueueError, 
file_dialog_complete_handler: fileDialogComplete, 
upload_progress_handler: uploadProgress, 
upload_error_handler: uploadError, 
upload_success_handler: uploadSuccess, 
upload_complete_handler: uploadComplete, 
// Button settings 
button_image_url: "/Style/Image/4-16.png", 
button_placeholder_id: "divBtn", 
button_width: 26, 
button_height: 26, 
// Flash Settings 
flash_url: "/swfupload/swfupload.swf", 
custom_settings: { 
upload_target: "divFileProgressContainer" 
}, 
// Debug Settings 
debug: false 
}); 
} 
// 文件校验 
function fileQueueError(file, errorCode, message) { 
try { 
switch (errorCode) { 
case SWFUpload.QUEUE_ERROR.ZERO_BYTE_FILE: 
alert("上传文件有错误！"); 
break; 
case SWFUpload.QUEUE_ERROR.FILE_EXCEEDS_SIZE_LIMIT: 
alert("上传文件超过（20M）！"); 
break; 
case SWFUpload.QUEUE_ERROR.ZERO_BYTE_FILE: 
case SWFUpload.QUEUE_ERROR.INVALID_FILETYPE: 
default: 
alert("文件出现错误！"); 
break; 
} 
} catch (ex) { 
this.debug(ex); 
} 
} 
// 文件选择完毕时触发 
function fileDialogComplete(numFilesSelected, numFilesQueued) { 
try { 
if (numFilesQueued > 0) { 
$("#divImgs").show(); 
for (var i = 0; i < numFilesQueued; i++) { 
$("#ulUpload").append('<li id="li' + i + '"><img class="imgload" src="https://www.gxlcms.com/style/image/loading.gif" " /></li>'); 
} 
this.startUpload(); 
} 
} catch (ex) { 
this.debug(ex); 
} 
} 
// 滚动条的处理方法 暂时没写 
function uploadProgress(file, bytesLoaded) { 
} 
// 每个文件上传成功后的处理 
function uploadSuccess(file, serverData) { 
try { 
var index = file.id.substr(file.id.lastIndexOf('_') + 1); 
$("#li" + index).html(""); 
$("#li" + index).html('<img src="' + serverData + '" "/>'); 
index++; 
} catch (ex) { 
this.debug(ex); 
} 
} 
// 上传完成后，触发下一个文件的上传 
function uploadComplete(file) { 
try { 
if (this.getStats().files_queued > 0) { 
this.startUpload(); 
} 
} catch (ex) { 
this.debug(ex); 
} 
} 
// 单个文件上传错误时处理 
function uploadError(file, errorCode, message) { 
var imageName = "imgerror.png"; 
try { 
var index = file.id.substr(file.id.lastIndexOf('_') + 1); 
$("#li" + index).html(""); 
$("#li" + index).html('<img src="https://www.gxlcms.com/style/image/imgerror.png" "/>'); 
index++; 
} catch (ex3) { 
this.debug(ex3); 
} 
} 
</script> 
</head> 
<body> 
<form id="form1" runat="server"> 
<div style="width: 600px;"> 
<div class="divTxt"> 
文本框 
</div> 
<div style="height: 30px; line-height: 30px;"> 
<div id="divBtn" style="float: left; width: 26px; height: 26px;"> 
</div> 
<div style="float: right;"> 
<input id="btnReply" type="button" value="发表" /> 
</div> 
</div> 
<div id="divImgs" style="border: 1px solid #cdcdcd; display: none;"> 
<div> 
上传图片</div> 
<ul id="ulUpload" class="ulUpload"> 
</ul> 
</div> 
</div> 
</form> 
</body> 
</html> 
 
使用Vs2010开发，以下为项目源码地址
 
 




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