阅读量:0
在Java Servlet中实现文件上传，通常使用Apache Commons FileUpload库。以下是使用该库实现文件上传的步骤：
- 添加依赖
首先，需要在项目中添加Apache Commons FileUpload库的依赖。如果你使用的是Maven，可以在pom.xml文件中添加以下依赖：
<dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.4</version> </dependency> <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.6</version> </dependency> - 创建Servlet
创建一个继承自HttpServlet的类，并重写doPost方法。在doPost方法中，使用ServletFileUpload类检查请求是否为文件上传类型。
import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.io.PrintWriter; import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; @WebServlet("/upload") public class FileUploadServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { if (!ServletFileUpload.isMultipartContent(request)) { response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Request is not multipart, please 'multipart/form-data' enctype for your form."); return; } PrintWriter out = response.getWriter(); response.setContentType("text/html"); response.setCharacterEncoding("UTF-8"); try { List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request); for (FileItem item : items) { if (!item.isFormField()) { // Process the uploaded file here // Save the file to the server or any other storage system // Generate the URL for the uploaded file String fileUrl = "http://example.com/files/" + item.getName(); out.println("<p>File uploaded successfully: " + fileUrl + "</p>"); } } } catch (Exception e) { out.println("<p>Error uploading file: " + e.getMessage() + "</p>"); } finally { out.close(); } } } - 创建上传表单
在HTML文件中创建一个包含文件输入字段的表单，并设置enctype属性为"multipart/form-data"。
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>File Upload</title> </head> <body> <h1>File Upload</h1> <form action="upload" method="post" enctype="multipart/form-data"> <input type="file" name="file" /> <input type="submit" value="Upload" /> </form> </body> </html> 现在，当用户选择一个文件并提交表单时，文件将被上传到服务器。在FileUploadServlet中，你可以处理上传的文件，将其保存到服务器或其他存储系统，并生成文件的URL。
