Java-WEB文件上传下载例程

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页面html代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>上传文件</title>
</head>
<body>
	<font color="red" size="3px"><b>${error}</b></font>
	<table border="1" width="60%">
		<tr>
			<th>用户名</th>
			<th>性别</th>
			<th>头像</th>
			<th>IP地址</th>
			<th>上传文件名</th>
			<th>操作</th>
		</tr>
		<c:forEach items="${list}" var="user">
			<tr>
				<td>${user.name}</td>
				<td>${user.sex==true?"男":"女"}</td>
				<td><img src="${user.pic}" height="120"></td>
				<td>${user.ip}</td>
				<td>${user.fileName}</td>
				<td><a href="/upload?mode=download&id=${user.id}">下载</a></td>
			</tr>
		</c:forEach>
	</table>
	<form action="/upload?mode=upload" method="post">
		<input type="submit" value="去上传..."/>
	</form>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>上传文件</title>
<script type="text/javascript">
	var tag = true;
	function go(){
		if(tag){
			document.forms[0].submit();
			tag = false;
		}else{
			alert("正在提交中，请勿重复提交请求……");
		}
	}
</script>
</head>
<body>
	<font color="red" size="3px"><b>${error}</b></font>
	<form action="/upload?mode=add" method="post" enctype="multipart/form-data">
		<input type="hidden" name="randomName" value="${randomName}"/>
		<input type="hidden" name="randomValue" value="${randomValue}"/>
		<table>
			<tr>
				 <td>用户名：</td>
				 <td><input type="text" name="name"/></td>
			</tr>	
			<tr>
				 <td>性 别：</td>
				 <td><input type="radio" name="sex" value="true"/>男
				 	 <input type="radio" name="sex" value="false"/>女
				 </td>
			</tr>	
			<tr>
				 <td>头 像：</td>
				 <td><input type="file" name="pic"/></td>
			</tr>	
			<!-- <tr>
				 <td>IP地址：</td>
				 <td><input type="text" name="ip"/></td>
			</tr> -->	
			<tr>
				 <td>文件名：</td>
				 <td><input type="file" name="fileName"/></td>
			</tr>	
			<tr>
				<!-- <td colspan="2" align="center"><input type="button" value="提交" onclick="go()"/></td> -->
				<td colspan="2" align="center"><input type="submit" value="提交""/>
			</tr>
		</table>
	</form>
</body>
</html>

java代码：

package cn.itcast.cd.domain;

public class User {
	private Long id;
	private String name;
	private Boolean sex;
	private String pic;
	private String ip;
	private String fileName;
	private String filePath;
	private long fileSize;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Boolean getSex() {
		return sex;
	}

	public void setSex(Boolean sex) {
		this.sex = sex;
	}

	public String getFileName() {
		return fileName;
	}

	public void setFileName(String fileName) {
		this.fileName = fileName;
	}

	public String getFilePath() {
		return filePath;
	}

	public void setFilePath(String filePath) {
		this.filePath = filePath;
	}

	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}

	public String getIp() {
		return ip;
	}

	public void setIp(String ip) {
		this.ip = ip;
	}

	public String getPic() {
		return pic;
	}

	public void setPic(String pic) {
		this.pic = pic;
	}

	public long getFileSize() {
		return fileSize;
	}

	public void setFileSize(long fileSize) {
		this.fileSize = fileSize;
	}

	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", sex=" + sex + ", pic="
				+ pic + ", ip=" + ip + ", fileName=" + fileName + ", filePath="
				+ filePath + ", fileSize=" + fileSize + "]";
	}
}

package cn.itcast.cd.dao;

import java.util.List;

import cn.itcast.cd.domain.User;

public interface IUserDAO {
	void add(User user);
	List<User> list();
	User get(Long id);
}


package cn.itcast.cd.daoImpl;

import java.sql.SQLException;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;

import cn.itcast.cd.Utils.Utils;

public class BaseDao {
	// 使用DbUtils中的QueryRunner对象.
	private QueryRunner queryRunner = new QueryRunner(Utils.getDataSource());
	/*
	 * 执行修改
	 */
	public void exeUpdate(String sql, Object... params) {
		try {
			queryRunner.update(sql, params);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	/*
	 * 执行查询
	 */
	public <T> T exeQuery(String sql, ResultSetHandler<T> rsh, Object... params) {
		try {
			return queryRunner.query(sql, rsh, params);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return null;
	}
}

package cn.itcast.cd.daoImpl;

import java.util.List;

import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;

import cn.itcast.cd.dao.IUserDAO;
import cn.itcast.cd.domain.User;

public class UserDAOImpl extends BaseDao implements IUserDAO {

	@Override
	public void add(User user) {
		String sql = "insert into user values(null, ?, ?, ?, ?, ?, ?)";
		Object[] params = { user.getName(), user.getSex(), user.getPic(), user.getIp(),
				user.getFileName(), user.getFilePath() };
		exeUpdate(sql, params);
	}

	@Override
	public List<User> list() {
		String sql = "select * from user";
		return exeQuery(sql, new BeanListHandler<User>(User.class));
	}

	@Override
	public User get(Long id) {
		String sql = "select * from user where id=?";
		return exeQuery(sql, new BeanHandler<User>(User.class), id);
	}
}


package cn.itcast.cd.servlet;

import java.io.IOException;
import java.lang.reflect.Method;

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

import org.apache.commons.lang3.StringUtils;

public class BaseServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;

	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		req.setCharacterEncoding("UTF-8");
		String mode = req.getParameter("mode");

		if (StringUtils.isNotBlank(mode)) {
			try {
				Method method = this.getClass().getMethod(mode,
						HttpServletRequest.class, HttpServletResponse.class);
				method.invoke(this, req, resp);
			} catch (Exception e) {
				e.printStackTrace();
			}
		} else {
			doMethod(req, resp); // 默认调用
		}
	}

	protected void doMethod(HttpServletRequest req, HttpServletResponse resp) {

	}
}

package cn.itcast.cd.servlet;

import java.io.File;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.FilenameUtils;

import cn.itcast.cd.Utils.MyException;
import cn.itcast.cd.Utils.UploadFileInfo;

public class MyHttpServletRequest extends HttpServletRequestWrapper {
	// 装在普通表单元素的map
	private Map<String, String> formFiledMap = new HashMap<String, String>();

	// 装在上传表单元素的Map
	private Map<String, FileItem> uploadFieldMap = new HashMap<String, FileItem>();

	Boolean isMultipartContent = false;

	public MyHttpServletRequest(HttpServletRequest request) {
		super(request);
		// 检查是否是文件上传请求
		isMultipartContent = ServletFileUpload.isMultipartContent(request);
		if (isMultipartContent) {
			// 创建工程，设置上传最大的内存空间和临时文件存放位置.
			FileItemFactory factory = new DiskFileItemFactory(1024 * 1024 * 10,
					new File("D:/tmp"));
			ServletFileUpload fileUpload = new ServletFileUpload(factory);
			fileUpload.setFileSizeMax(1024 * 1024); // 设置单个文件上传的最大值为1M.
			fileUpload.setSizeMax(1024 * 1024 * 5); // 设置整个表单的文件上传最大值为5M.
			try {
				List<FileItem> fileItems = fileUpload.parseRequest(request);
				for (FileItem fileItem : fileItems) {
					// 是否是普通表单元素，即type不为file的表单元素
					if (fileItem.isFormField()) {
						formFiledMap.put(fileItem.getFieldName(),
								fileItem.getString("UTF-8"));
					} else {
						if (fileItem.getSize() > 0) {
							uploadFieldMap.put(fileItem.getFieldName(),
									fileItem);
						}
					}
				}
			} catch (SizeLimitExceededException e) {
				throw new MyException("上传文件的大小超过限制！");
			} catch (FileUploadException e) {
				e.printStackTrace();
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
		}
	}

	// 包装原来的方法
	@Override
	public String getParameter(String name) {
		// 是上传文件的表单，要得到参数值，直接根据name，取存在map中的值.
		if (isMultipartContent) {
			return formFiledMap.get(name);
		} else {
			return super.getParameter(name);
		}
	}

	// 已经将Map修改了，覆盖原来的方法
	@Override
	public Map getParameterMap() {
		if (isMultipartContent) {
			return formFiledMap;
		} else {
			return super.getParameterMap();
		}
	}

	/**
	 * 上传表单中指定表单元素中的文件.
	 * 
	 * @param formFieldName
	 *            表单中元素的名称
	 * @param tagPath
	 *            上传的目标目录，即服务器上存放上传文件的目录.
	 * 
	 * @return 由于上传成功后，我们需要将上传的文件名和文件地址存放到数据库，
	 *         也即需要返回给Servlet上传的文件信息，故将文件信息封装成一个对象返回.
	 * 
	 */
	public UploadFileInfo upload(String formFieldName, String tagPath) {
		FileItem fileItem = uploadFieldMap.get(formFieldName);
		if (fileItem != null) {
			// 得到文件名fileItem.getName()有些浏览器可能得到的是全路径，而这里只需要文件名
			String srcFileName = FilenameUtils.getName(fileItem.getName()); 
			long fileSize = fileItem.getSize();

			//不同的用户可能上传相同的文件名，不处理就被覆盖，所以这里需要用唯一标示进行文件区分.
			String tagFilePath = tagPath + "/" + UUID.randomUUID().toString() + "." + FilenameUtils.getExtension(srcFileName); 
			
			if (!tagPath.startsWith("/")){
				tagPath = "/" + tagPath;
			}
			
			//判断目录是否存在，不存在就创建
			File dir = new File(getSession().getServletContext().getRealPath("/") + tagPath);
			if (!dir.exists()) {
				dir.mkdirs();
			}
			
			//写到指定目录
			try {
				fileItem.write(new File(getSession().getServletContext().getRealPath("/"), tagFilePath));
			} catch (Exception e) {
				e.printStackTrace();
			}
			return new UploadFileInfo(srcFileName, tagFilePath, fileSize);		
		}
		return null;
	}
}

package cn.itcast.cd.servlet;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.List;
import java.util.UUID;

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

import org.apache.catalina.startup.SetAllPropertiesRule;
import org.apache.commons.lang3.StringUtils;

import cn.itcast.cd.Utils.MyException;
import cn.itcast.cd.Utils.UploadFileInfo;
import cn.itcast.cd.dao.IUserDAO;
import cn.itcast.cd.daoImpl.UserDAOImpl;
import cn.itcast.cd.domain.User;

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

	IUserDAO dao = null;

	@Override
	public void init() throws ServletException {
		dao = new UserDAOImpl();
	}

	public void add(HttpServletRequest request, HttpServletResponse response)
			throws InterruptedException {
		// request不能接收上传文件的表单参数，返回全部为null，所以用MyHttpServletRequest类进行包装，单独处理.

		// Thread.sleep(1000);

		MyHttpServletRequest myRequest = null;
		try {
			myRequest = new MyHttpServletRequest(request);
		} catch (MyException e) { // 捕捉自定义异常，提示用户上传文件的大小限制
			request.setAttribute("error", e.getMessage());
			upload(request, response);
			return;
		}

		/*
		 * 从页面得到标示信息，由于是文件上传的请求，必须用myRequest
		 */
		String randomName = myRequest.getParameter("randomName");
		String randomValue = myRequest.getParameter("randomValue");
		//session中的标示.
		String randomValueInSession = (String) myRequest.getSession().getAttribute(randomName);
		
//		System.out.println(randomName + " " + randomValue + " " + randomValueInSession);
		
		if(StringUtils.isNotBlank(randomValueInSession) && 
					StringUtils.isNotBlank(randomValue) && StringUtils.isNotBlank(randomName)
					&& randomValueInSession.equals(randomValue)){
			// 接收普通表单元素的参数信息
			String name = myRequest.getParameter("name");
			String sex = myRequest.getParameter("sex");

			// 封装对象
			User user = new User();
			user.setName(name);
			user.setSex(Boolean.parseBoolean(sex));

			String ip = request.getRemoteAddr();
			user.setIp(ip);

			// 上传头像信息
			UploadFileInfo picInfo = myRequest.upload("pic", "/headPic");
			if (picInfo != null) {
				user.setPic(picInfo.getTagFilePath());
			}

			UploadFileInfo fileInfo = myRequest.upload("fileName",
					"/WEB-INF/resource");
			if (fileInfo != null) {
				user.setFilePath(fileInfo.getTagFilePath());
				user.setFileName(fileInfo.getSrcFileName());
				user.setFileSize(fileInfo.getFileSize());
			}

			dao.add(user);

			//提交完成移除session中设置的随机标示
			request.getSession().removeAttribute(randomName);
		} else {
			request.setAttribute("error", "重复提交请求……");
		}	
		list(request, response);
	}

	public void list(HttpServletRequest request, HttpServletResponse response) {
		List<User> list = dao.list();
		request.setAttribute("list", list);
		try {
			request.getRequestDispatcher("/WEB-INF/jsp/list.jsp").forward(
					request, response);
		} catch (ServletException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public void upload(HttpServletRequest request, HttpServletResponse response) {
		try {
			//防止重复提交
			String randomName = UUID.randomUUID().toString();
			String randomValue = UUID.randomUUID().toString();
			
			request.setAttribute("randomName", randomName );
			request.setAttribute("randomValue", randomValue);
			//当前产生的标示放到session.
			request.getSession().setAttribute(randomName, randomValue);
			
			request.getRequestDispatcher("/WEB-INF/jsp/upload.jsp").forward(
					request, response);
			
		} catch (ServletException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	@Override
	protected void doMethod(HttpServletRequest request,
			HttpServletResponse response) {
		list(request, response);
	}

	public void download(HttpServletRequest request,
			HttpServletResponse response) {
		String id = request.getParameter("id");
		User user = dao.get(Long.parseLong(id));

		// 发送下载请求给浏览器
		response.setContentType("application/x-msdownload");
		try {
			// 解决下载时文件名乱码问题.
			response.setHeader("Content-Disposition", "attachment;filename="
					+ URLEncoder.encode(user.getFileName(), "utf-8"));
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}

		BufferedOutputStream bos = null;
		BufferedInputStream bis = null;
		try {
			bos = new BufferedOutputStream(response.getOutputStream());
			bis = new BufferedInputStream(new FileInputStream(new File(
					getServletContext().getRealPath("/"), user.getFilePath())));

			byte[] b = new byte[1024];

			int lenth = 0;
			while ((lenth = bis.read(b)) != -1) {
				bos.write(b, 0, lenth);
				bos.flush();
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				bos.close();
				bis.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}


package cn.itcast.cd.Utils;

public class MyException extends RuntimeException {
	public MyException(String message){
		super(message);
	}
}

package cn.itcast.cd.Utils;

public class UploadFileInfo {
	private String srcFileName;
	private String tagFilePath;
	private long fileSize;
	public String getSrcFileName() {
		return srcFileName;
	}
	public void setSrcFileName(String srcFileName) {
		this.srcFileName = srcFileName;
	}
	public String getTagFilePath() {
		return tagFilePath;
	}
	public void setTagFilePath(String tagFilePath) {
		this.tagFilePath = tagFilePath;
	}
	public long getFileSize() {
		return fileSize;
	}
	public void setFileSize(long fileSize) {
		this.fileSize = fileSize;
	}
	public UploadFileInfo(String srcFileName, String tagFilePath, long fileSize) {
		super();
		this.srcFileName = srcFileName;
		this.tagFilePath = tagFilePath;
		this.fileSize = fileSize;
	}
}

package cn.itcast.cd.Utils;

import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSourceFactory;

public class Utils {
	private static DataSource dataSource;
	
	static{
		Properties properties = new Properties();
		try {
			properties.load(Utils.class.getClassLoader().getResourceAsStream("jdbc.properties"));
			dataSource = BasicDataSourceFactory.createDataSource(properties);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public static DataSource getDataSource(){
		return dataSource;
	}
}

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