上傳圖片功能源碼

上傳圖片
------
使用apache的上傳附件插件：commons-fileupload.jar
			commons-io.jar
A:創建頁面：upload.jsp
B：編寫servlet:PicUploadServlet.java
c:配置web.xml

jsp
-----------
	<!-- 上傳附件的表單(二進制數據)注意兩點：
		1、post請求，
		2、enctype="multipart/form-data" -->
	<form name="myForm" action="${pageContext.request.contextPath }/picUpload" 
	method="post" enctype="multipart/form-data">
		username:<input type="text" name="username"><br/>
		file:<input type="file" name="file" />
				<input type="submit" value="上傳">
	</form>

servlet
---------
public class PicUploadServlet extends HttpServlet
{
    private File tempPath = null;
    private File uploadPath = null;
    //初始化文件上傳的目錄
    //1、存儲圖片的臨時路徑
    //2、存放（上傳）文件的真實路徑
    @Override
    public void init()
        throws ServletException
    {
        //獲取臨時交換目錄
        tempPath = new File(this.getServletContext().getRealPath("temp"));
        System.out.println(this.getServletContext().getRealPath("temp"));
        if(!tempPath.exists())
        {
            tempPath.mkdir();
        }
        //獲取上傳文件的真實路徑
        uploadPath = new File(this.getServletContext().getRealPath("upload/images"));
        if(!uploadPath.exists())
        {
            //創建多級目錄
            uploadPath.mkdirs();
        }
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException
    {
        DiskFileItemFactory factory = new DiskFileItemFactory();
        //設置文件上傳的大小塊4k
        factory.setSizeThreshold(4096);
        factory.setRepository(tempPath);
        //創建上傳組件
        ServletFileUpload upload = new ServletFileUpload(factory);
        //設置文件上傳大小 4M
        upload.setSizeMax(4096000);
        //得到表單元素列表
        try
        {
            List fileItems = upload.parseRequest(req);
            //遍歷該集合
            Iterator fileItem = fileItems.iterator();
            String username = "";
            while(fileItem.hasNext())
            {
                FileItem item = (FileItem)fileItem.next();
                //判斷該元素是否爲普通表單元素
                if(item.isFormField())
                {
                    if("username".equals(item.getFieldName()))
                    {
                        username = item.getString("utf-8");
                        System.out.println(username);
                    }
                }
                //附件上傳元素
                else
                {
                    String fileName = item.getName();
                    //獲取後綴名
                    String ext = fileName.substring(fileName.lastIndexOf(".")+1, fileName.length());
                    //得到一個不會重複的文件名
                    Calendar c = Calendar.getInstance();
                    fileName = String.valueOf(c.getTimeInMillis());
                    //fileName = c.getTimeInMillis()+"";
                    //拼接一個帶不會重複的文件名的全路徑
                    String fullFilePath = uploadPath+"/"+fileName+"."+ext;
                    //將緩存中的二進制流的附件，寫入該路徑(附件存放在磁盤下的具體路徑)
                    File f = new File(fullFilePath);
                    item.write(f);
                    //將上面的原圖同時生成一張等比例縮放的縮略圖
                    //創建一個縮略圖的全路徑
                    String newurl = uploadPath+"/"+fileName+"_min."+ext;
                    //構建image對象
                    Image src = ImageIO.read(f);
                    //設置目標大小
                    float tagSize = 200;
                    int oldWidth = src.getWidth(null);
                    int oldHeight = src.getHeight(null);
                    //定義新的高度和寬度
                    int newWidth=0;
                    int newHeight=0;
                    //聲明臨時大小
                    float tempDouble=0;
                    //橫放
                    if(oldWidth > oldHeight)
                    {
                        tempDouble = oldWidth/tagSize;
                    }
                    else
                    {
                        tempDouble = oldHeight/tagSize;
                    }
                    //得到新的高度和寬度
                    newWidth = Math.round(oldWidth/tempDouble);
                    newHeight = Math.round(oldHeight/tempDouble);
                    //創建新圖對象
                    BufferedImage tag = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
                    tag.getGraphics().drawImage(src, 0, 0,newWidth,newHeight,null);
                    FileOutputStream newImage = new FileOutputStream(newurl);
                    //創建編碼對象
                    JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(newImage);
                    //JPEG編碼
                    encoder.encode(tag);
                    //關閉流
                    newImage.close();
                }
            }
            req.getRequestDispatcher("success.jsp").forward(req, resp);
        }
        catch (FileUploadException e)
        {
            e.printStackTrace();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}