Servlet 上传文件

最新推荐文章于 2025-04-21 20:37:30 发布

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最新推荐文章于 2025-04-21 20:37:30 发布

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分类专栏： java web 文章标签： servlet 上传文件 MultiPartRequestWrapper 纯servlet 上传压缩包

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java web中在不使用第三方jar的情况下如何使用servlet 上传文件呢？

（1）上传表单，文件名为upload_servlet.jsp，内容如下：

<?xml version="1.0" encoding="UTF-8" ?>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://"
			+ request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!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>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>servlet upload file</title>
</head>
<body>
<center>
<form action="<%=basePath %>servlet/upload.servlet" enctype="multipart/form-data"
			method="post"  >
<input type="file" name="file2"  />
<br />
<input type="submit" value="上传" />
</form>
<br />
<a href="../index.jsp">index</a>
</center>
</body>
</html>

注意：上传文件表单必须指定 enctype="multipart/form-data" 和method="post"

（2）后台servlet，名称是UploadFileServlet，代码如下：

package com.shop.jn.web.servlet;

import java.io.File;
import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.dispatcher.multipart.MultiPartRequestWrapper;

import com.common.util.SystemHWUtil;
import com.common.web.servlet.upload.SUploadServlet;

/**
 * Servlet implementation class UploadFileServlet
 */
public class UploadFileServlet extends SUploadServlet {
	private static final long serialVersionUID = 1L;
       
    

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("UploadFileServlet");
		if(request instanceof MultiPartRequestWrapper){
			MultiPartRequestWrapper mp=(MultiPartRequestWrapper)request;
			Enumeration<String> multi=mp.getFileParameterNames();
			String formFileTagName=null;//"file2"
			for( ;multi.hasMoreElements();){
				String element=multi.nextElement();
				formFileTagName=element;//表单中标签的名称：file标签的名称

				break;
			}
			String fileName=mp.getFileNames(formFileTagName)[0];//上传的文件名
			//保存到哪儿
			File savedFile=super.getUploadedFilePath(request, "upload", fileName);//D:\eclipse\workspace\shop_goods\ upload
			
			File[]files=mp.getFiles(formFileTagName);
			File uploadFile=files[0];//上传的文件
			SystemHWUtil.copyFile(uploadFile, savedFile/*new File("D:\\Temp\\a\\a\\c.zip")*/);
			uploadFile.delete();
		}
		response.sendRedirect("../upload_download/upload_servlet.jsp");

				
	}

}

说明：上传的文件保存到项目根目录下的upload文件夹中。

注意：上述servlet只能处理单文件上传。

servlet在web.xml中的配置如下：

 <servlet>
    <servlet-name>UploadFileServlet</servlet-name>
    <servlet-class>com.shop.jn.web.servlet.UploadFileServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>UploadFileServlet</servlet-name>
    <url-pattern>/servlet/upload.servlet</url-pattern>
  </servlet-mapping>

UploadFileServlet 中使用的方法的源码

SystemHWUtil.copyFile（jar io0007-find_progess_中的类com.common.util.SystemHWUtil）：

/**
	 * 
	 * @param srcFile
	 *            :must be regular file,can not be folder;
	 * @param targetFile
	 *            :must be regular file,can not be folder;
	 * @throws IOException
	 */
	public static void copyFile(File srcFile, File targetFile)
			throws IOException {
		FileInputStream in = new FileInputStream(srcFile);

		FileOutputStream out = new FileOutputStream(targetFile);
		copyFile(in, out);

	}

	public static void copyFile(InputStream in, FileOutputStream target)
			throws IOException {
		// File targetFile = new File(targetFileName);
		// FileOutputStream target = null;
		// if (targetFile.isDirectory())
		// {
		// targetFile = new File(targetFile, simpleName);
		// }
		try {
			// target = new FileOutputStream(targetFile);
			byte[] buffer = new byte[BUFF_SIZE];
			int byteNum;

			while ((byteNum = in.read(buffer)) != NEGATIVE_ONE) {
				target.write(buffer, 0, byteNum);

			}
			System.out.println("[SystemUtil:copyFile]:file copy successfully!");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (in != null) {
				in.close();
				in = null;
			}
			if (target != null) {
				target.close();
				target = null;
			}
		}
	}

WebServletUtil.getUploadedPath（jar io0007-find_progess_中的类com.common.util.WebServletUtil）：

/***
	 * java web //
	 * D:\xxx\eclipse\workspace\.metadata\.plugins\org.eclipse.wst.server
	 * .core\tmp0\wtpwebapps\shop_goods\images //
	 * D:\xxx\eclipse\workspace\shop_goods\ upload
	 * 
	 * @param uploadFolderName
	 * @param projectName
	 * @param sContext
	 * @return
	 */
	public static String getUploadedPath(String uploadFolderName,
			String projectName, ServletContext sContext) {
		String uploadFolder_tmp = null;
		if (uploadFolderName.startsWith("/")) {
			uploadFolder_tmp = uploadFolderName;
		} else {
			uploadFolder_tmp = "/" + uploadFolderName;// "/upload"
		}
		String realpath = sContext.getRealPath(uploadFolder_tmp);
		// project name ,eg.shop_goods
		projectName = SystemHWUtil.deleteFrontSlash(projectName);
		realpath = SystemHWUtil.getRealPath(realpath, projectName);
		return realpath;
	}

注意：

（1）使用的容器是tomcat，不是jetty；

（2）没有使用第三方上传jar包

依赖的jar见附件