文件上传-前后端(HTML+Servelt)

1.引入包

实现文件上传需要使用到SmartUpload组件，需要引入对应jar包：

SmartUpload.jar

2.代码实现

前端

form标签必须加上 method="post" enctype="multipart/form-data" ，否则无法上传到servlet

<form id="booksAdd_form" method="post" enctype="multipart/form-data"					action="${pageContext.request.contextPath}/books/BooksAddServlet">
							<table class="table table-bordered text-center">
								<tr>
									<th style="vertical-align: middle;">书籍封面</th>
									<td style="vertical-align: middle;">
								
									<div class="input-group">
									<input id="bookImg" type="file" class="form-control" name="bookImg" style="align:center">
									
									</div>	
										
									</td>
								</tr>

							</table>
						</form>

后端

• servlet层

public class BooksAddServlet extends HttpServlet {
       
	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//创建SmartUpload
		SmartUpload su=new SmartUpload();
		String filename=null;//文件名
		//初始化对象，规定写法，无需理解
		su.initialize(this.getServletConfig(), request, response);
		//生成文件名，ip+当前时间戳+三位随机数（保证文件名唯一）
		filename="/upload/"+new UploadDao().uploadPicture(su,request);
		//将二进制内容转回正常的request
		Request req=su.getRequest();
		//将文件路径存入数据库
		Books book=new Books();
		book.setImg(filename);
		int result=new BooksDao().addBooks(book);
		request.getRequestDispatcher("BooksServlet").forward(request, response);
	}
}

• service层

public class UploadService {
//定义服务器保存文件的路径
	static final String filePath = "E:/Code/EclipseEEWorkspace/books_manager/WebContent/WEB-INF/upload/";

	// 上传图书封面
	public String uploadPicture(SmartUpload su, HttpServletRequest request) {
		String filename = null;

		try {
		//上传准备
			su.upload();
		} catch (ServletException | IOException | SmartUploadException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		//获取文件
		Files fs = su.getFiles();
		File f = fs.getFile(0);
		//获取自定义的文件名称
		filename = this.getUploadFilename(request, f);
		try {
		//另存为定义的路径
			su.getFiles().getFile(0).saveAs(filePath + filename);
//					su.save(filePath);
		} catch (IOException | SmartUploadException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return filename;

	}