图片上传格式以及尺寸大小的限制

首先需要上传图片的jsp页面是这样的,从选择文件这里选择图片.

下面是jsp的部分页面.

 <body>
  <div>
   <p style="font-weight: 900; color: red;">${msg }</p>
   <form action="<c:url value='/admin/AdminAddBookServlet'/>" enctype="multipart/form-data" method="post" id="form">
    <div>
	    <ul>
	    	<li>书名：　<input id="bname" type="text" name="bname" value="Spring实战(第3版)（In Action系列中最畅销的Spring图书，近十万读者学习Spring的共同选择）" style="width:500px;"/></li>
	    	<li>大图：　<input id="image_w" type="file" name="image_w"/></li>
	    	<li>小图：　<input id="image_b" type="file" name="image_b"/></li>
	    	<li>当前价：<input id="price" type="text" name="price" value="40.7" style="width:50px;"/></li>
	    	<li>定价：　<input id="currPrice" type="text" name="currPrice" value="59.0" style="width:50px;"/>
	    	折扣：<input id="discount" type="text" name="discount" value="6.9" style="width:30px;"/>折</li>
	    </ul>
		<hr style="margin-left: 50px; height: 1px; color: #dcdcdc"/>
		<table>
			<tr>
				<td colspan="3">
					作者：　　<input type="text" id="author" name="author" value="Craig Walls" style="width:150px;"/>
				</td>
			</tr>
			<tr>
				<td colspan="3">
					出版社：　<input type="text" name="press" id="press" value="人民邮电出版社" style="width:200px;"/>
				</td>
			</tr>
			<tr>
				<td colspan="3">出版时间：<input type="text" id="publishtime" name="publishtime" value="2013-6-1" style="width:100px;"/></td>
			</tr>
			<tr>
				<td>版次：　　<input type="text" name="edition" id="edition" value="1" style="width:40px;"/></td>
				<td>页数：　　<input type="text" name="pageNum" id="pageNum" value="374" style="width:50px;"/></td>
				<td>字数：　　<input type="text" name="wordNum" id="wordNum" value="48700" style="width:80px;"/></td>
			</tr>
			<tr>
				<td width="250">印刷时间：<input type="text" name="printtime" id="printtime" value="2013-6-1" style="width:100px;"/></td>
				<td width="250">开本：　　<input type="text" name="booksize" id="booksize" value="16" style="width:30px;"/></td>
				<td>纸张：　　<input type="text" name="paper" id="paper" value="胶版纸" style="width:80px;"/></td>
			</tr>
			<tr>
				<td>
					一级分类：<select name="pid" id="pid" onchange="loadChildren()">
						<option value="">==请选择1级分类==</option>
			    	<c:forEach items="${parents}" var="parent">
			    		<option value="${parent.cid}">${parent.cname}</option>
			    	</c:forEach>
					</select>
				</td>
				<td>
					二级分类：<select name="cid" id="cid">
						<option value="">==请选择2级分类==</option>
					</select>
				</td>
				<td></td>
			</tr>
			<tr>
				<td>
					<input type="button" id="btn" class="btn" value="新书上架">
				</td>
				<td></td>
				<td></td>
			</tr>
		</table>
	</div>
   </form>
  </div>
  </body>

下面是servlet中的限制图片尺寸,格式的代码.

package cn.itcast.goods.admin.book.web.servlet;

import java.awt.Image;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.swing.ImageIcon;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import cn.itcast.commons.CommonUtils;
import cn.itcast.goods.book.domain.Book;
import cn.itcast.goods.book.service.BookService;
import cn.itcast.goods.category.domain.Category;

public class AdminAddBookServlet extends HttpServlet {

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		
		/*
		 * 1. commons-fileupload的上传三步
		 */
		FileItemFactory factory = new DiskFileItemFactory();		//disk...Factory这个构造器可以给参数(缓存大小 or 缓存目录),不给缓存大小就是 10KB
		/*
		 * 2.创建解析器对象
		 */
		ServletFileUpload sfu = new ServletFileUpload(factory);
		sfu.setFileSizeMax(80 * 1024);			//设置单个上传的文件上限为  80KB
		/*
		 * 3.解析request得到List<FileItem>
		 */
		List<FileItem> fileItemList = null(此处写空Null,不知道为什么浏览器没显示);
		try {
			fileItemList = sfu.parseRequest(request);
		} catch (FileUploadException e) {
			//如果出现这个异常,说明单个文件超出了 80 KB
			error("上传的文件超出了80KB", request, response);
			return;
		}
		
		/*
		 * 4.把List<FileItem>封装到book对象中
		 * 4.1首先把"普通表单字段"放到一个map中,再把map转换成book和category对象,再建立两者的关系.
		 */
		Map<String, Object> map = new HashMap<String, Object>();
		for(FileItem fileItem : fileItemList){
			if(fileItem.isFormField()){				//如果是普通表单字段
			map.put(fileItem.getFieldName(), fileItem.getString("UTF-8"));
			}
		}
		Book book = CommonUtils.toBean(map, Book.class);				//把Map中的大部分数据封装到book对象中
		Category category = CommonUtils.toBean(map, Category.class);	//把map中的cid封装到category中
		book.setCategory(category);
		
		/*
		 * 4.2把上传的图片保存起来
		 *  >获取文件名:截取之
		 *  >给文件添加前缀:使用uuid前缀,为了避免文件同名现象
		 *  >校验文件的扩展名:只能是jpg
		 *  >校验图片的尺寸
		 *  >指定图片的保存路径,这需要使用ServletContext#getRealPath()
		 *  >保存之
		 *  >把图片的路径设置给book对象
		 */
		
		//获取文件名
		FileItem fileItem = fileItemList.get(1);				//获取大图
		String filename = fileItem.getName();
		//截取文件名,因为部分浏览器上传的是绝对路径
		int index = filename.lastIndexOf("\\");
		if(index !=-1){
			filename = filename.substring(index + 1);
		}
		//给文件名添加uuid的前缀,避免文件重名现象
		filename = CommonUtils.uuid() + "_" + filename;
		//校验文件的扩展名
		if(!filename.toLowerCase().endsWith(".jpg")){		//将大写转换成小写进行比较
			error("上传的图片扩展名必须是JPG", request, response);
			return;
		}
		//校验图片的尺寸
		//保存上传的图片,把图片new成图片对象: Image,Icon,ImageIcon,BufferedImage,ImageIO
		/*
		 *保存图片:
		 *1.获取真实路径
		 */
		String savepath = this.getServletContext().getRealPath("/book_img");
		/*
		 * 2.创建目标文件 
		 */
		File destFile = new File(savepath,filename);
		/*
		 * 3.保存文件
		 */
		try {
			fileItem.write(destFile);//它会把临时文件重定向到指定的路径,再删除临时文件
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
		//校验尺寸
		//1.使用文件路径创建ImageIcon
		ImageIcon icon = new ImageIcon(destFile.getAbsolutePath());
		//2.通过ImageIcon得到Image对象
		Image image = icon.getImage();
		//3.获取宽高来进行校验
		if(image.getWidth(null)>350 || image.getHeight(null)>350){
			error("您上传的图片尺寸超出了350*350像素!", request, response);
			destFile.delete();			//删除图片
			return;
		}
		//把图片的路径设置给book对象
		book.setImage_w("book_img/" + filename);
		
		
		//获取文件名
		fileItem = fileItemList.get(2);				//获取小图
		filename = fileItem.getName();
		//截取文件名,因为部分浏览器上传的是绝对路径
		index = filename.lastIndexOf("\\");
		if(index !=-1){
			filename = filename.substring(index + 1);
		}
		//给文件名添加uuid的前缀,避免文件重名现象
		filename = CommonUtils.uuid() + "_" + filename;
		//校验文件的扩展名
		if(!filename.toLowerCase().endsWith(".jpg")){
			error("上传的图片扩展名必须是JPG", request, response);
			return;
		}
		//校验图片的尺寸
		//保存上传的图片,把图片new成图片对象: Image,Icon,ImageIcon,BufferedImage,ImageIO
		/*
		 *保存图片:
		 *1.获取真实路径
		 */
		savepath = this.getServletContext().getRealPath("/book_img");
		/*
		 * 2.创建目标文件 
		 */
		destFile = new File(savepath,filename);
		/*
		 * 3.保存文件
		 */
		try {
			fileItem.write(destFile);//它会把临时文件重定向到指定的路径,再删除临时文件
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
		//校验尺寸
		//1.使用文件路径创建ImageIcon
		icon = new ImageIcon(destFile.getAbsolutePath());
		//2.通过ImageIcon得到Image对象
		image = icon.getImage();
		//3.获取宽高来进行校验
		if(image.getWidth(null)>350 || image.getHeight(null)>350){
			error("您上传的图片尺寸超出了350*350像素!", request, response);
			destFile.delete();			//删除图片
			return;
		}
		//把图片的路径设置给book对象
		book.setImage_b("book_img/" + filename);
		
		
		//调用service完成保存
		book.setBid(CommonUtils.uuid());
		BookService bookService = new BookService();
		bookService.add(book);
		
		//保存成功信息转发到msg.jsp
		request.setAttribute("msg", "添加图书成功!");
		request.getRequestDispatcher("/adminjsps/msg.jsp").forward(request, response);
	}
	
	/*
	 * 保存错误信息,转发到add.jsp
	 */
	private void error(String msg, HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setAttribute("msg", msg);
		request.getRequestDispatcher("/adminjsps/admin/book/add.jsp").forward(request, response);
	}

}

下面是bookservice的添加方法.

public class BookService {
	private BookDao bookDao = new BookDao();
	/**
	 * 添加图书
	 * @param book
	 */
	public void add(Book book){
		try {
			bookDao.add(book);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			throw new RuntimeException(e);
		}
	}
}

下面是bookDao的sql代码.

public class BookDao {
	private QueryRunner qr = new TxQueryRunner();
	/**
	 * 添加图书
	 * @param book
	 * @throws SQLException 
	 */
	public void add(Book book) throws SQLException {
		String sql = "insert into t_book(bid,bname,author,price,currPrice,"+
				"discount,press,publishtime,edition,pageNum,wordNum,printtime,"+
				"booksize,paper,cid,image_w,image_b)"+
				"values(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
		Object[] params = {book.getBid(),book.getBname(),book.getAuthor(),
						   book.getPrice(),book.getCurrPrice(),book.getDiscount(),
						   book.getPress(),book.getPublishtime(),book.getEdition(),
						   book.getPageNum(),book.getWordNum(),book.getPrinttime(),
						   book.getBooksize(),book.getPaper(),book.getCategory().getCid(),
						   book.getImage_w(),book.getImage_b()};
		qr.update(sql,params);
	}
}

图片上传格式以及尺寸大小的限制

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