JAVAWeb+JSP+servlet实现文件的上传和下载
准备工作：
导入jar包
- 文件上传依赖包： commons-fileupload-1.3.3.jar 和 commons-io-2.6.jar
- jsp标准标签库： jstl.jar 和 standard.jar
导入jquery-3.4.1.js
文件上传
FileUpload.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
文件上传
上传后的消息显示
message.jsp （此处加入了服务器保存的文件查看的超链接）
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
文件上传结果
${message}
文件查看
文件上传功能转自https://www.runoob.com/jsp/jsp-file-uploading.html
文件查看和下载部分
js中实现了文件的下载（post请求 以表单形式提交文件信息 : 文件名和文件绝对路径 ）
FileSelect.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
下载
文件名
${fileInfo.filename}
文件路径
${fileInfo.filepath}
下载
删除
文件下载是否成功的提示
success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
Title
${message}
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
Title
${message}
web.xml中的配置
UpLoad
com.lly.Fileupload
UpLoad
/fileupload
selectFile
com.lly.FileSelect
selectFile
/selectFile
fileHandle
com.lly.fileHandle
fileHandle
/fileHandle
后台servlet编写
文件上传 Fileupload.class
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
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.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
@WebServlet(name = "Fileupload")
public class Fileupload extends HttpServlet {
private static final long serialVersionUID = 1L; //序列号
// 上传文件存储目录
public static final String UPLOAD_DIRECTORY = "LLYSpace";
// 上传配置
private static final int MEMORY_THRESHOLD = 1024 * 1024 * 30; // 30MB //内存阈值
private static final int MAX_FILE_SIZE = 1024 * 1024 * 400; // 400MB //最大文件大小
private static final int MAX_REQUEST_SIZE = 1024 * 1024 * 500; // 500MB //最大请求大小
/**
* 上传数据及保存文件
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
FileUpload(request, response);
}
private synchronized void FileUpload(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
response.setContentType("text/html; charset=utf-8");
//设置字符集编码用于支持汉字显示
request.setCharacterEncoding("utf-8");
// 检测是否为多媒体上传
if (!ServletFileUpload.isMultipartContent(request)) {
// 如果不是则停止
PrintWriter writer = response.getWriter();
writer.println("Error: 表单必须包含 enctype=multipart/form-data");
writer.flush();
return;
}
// 配置上传参数 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload
DiskFileItemFactory factory = new DiskFileItemFactory();
// 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
factory.setSizeThreshold(MEMORY_THRESHOLD);
// 设置临时存储目录（）
factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
// 用以上工厂实例化上传组件
ServletFileUpload upload = new ServletFileUpload(factory);
// 设置最大文件上传值
upload.setFileSizeMax(MAX_FILE_SIZE);
// 设置最大请求值 (包含文件和表单数据)
upload.setSizeMax(MAX_REQUEST_SIZE);
// 中文处理
upload.setHeaderEncoding("UTF-8");
// 构造临时路径来存储上传的文件
// 这个路径相对当前应用的目录
String uploadPath = getServletContext().getRealPath("/") + File.separator + UPLOAD_DIRECTORY;
System.out.println(uploadPath); //打印文件夹路径
// 如果目录不存在则创建
File uploadDir = new File(uploadPath);
if (!uploadDir.exists()) {
uploadDir.mkdir();
}
try {
// 解析请求的内容提取文件数据
@SuppressWarnings("unchecked")
List
if (formItems != null && ((List) formItems).size() > 0) {
// 迭代表单数据
for (FileItem item : formItems) {
// 处理不在表单中的字段
if (!item.isFormField()) {
String fileName = new File(item.getName()).getName();
String filePath = uploadPath + File.separator + fileName;
File storeFile = new File(filePath);
// 保存文件到硬盘
item.write(storeFile);
request.setAttribute("message", "文件上传成功!");
}
}
}
} catch (Exception ex) {
request.setAttribute("message", "错误信息: " + ex.getMessage());
}
// 跳转到 message.jsp
getServletContext().getRequestDispatcher("/message.jsp").forward(request, response);
}
}
文件查看 FileSelect.class 此处用到了文件信息对象，所有要创建一个FileInfo类存储文件信息
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class FileSelect extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String uploadPath = getServletContext().getRealPath("/") + File.separator + Fileupload.UPLOAD_DIRECTORY; //文件夹路径
File file = new File(uploadPath);
ArrayList Arraylist =getAllFiles(file);
List list = new ArrayList<>();
for (File file1 : Arraylist) {
FileInfo fileInformation = new FileInfo();
fileInformation.setFilename(file1.getName());
fileInformation.setFilepath(file1.getAbsolutePath());
fileInformation.setTranspath(file1.getAbsolutePath().replace(File.separator,"%2F"));
list.add(fileInformation);
}
req.setAttribute("list", list);
req.getRequestDispatcher("FileSelect.jsp").forward(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
super.doPost(req, resp);
}
//遍历文件夹下所有文件放入ArrayList集合中
public ArrayList getAllFiles(File file) {
ArrayList list = new ArrayList<>();
File[] files = file.listFiles();
for (int i = 0; i < files.length; i++) {
if (files[i].isDirectory()) {
list.addAll(getAllFiles(files[i]));
} else if (files[i].isFile()) {
list.add(files[i]);
}
}
return list;
} 文件信息类：FileInfo.class
public class FileInfo {
private String filename;
private String filepath;
private String transpath;
public FileInfo() {
}
public FileInfo(String filename, String filepath, String transpath) {
this.filename = filename;
this.filepath = filepath;
this.transpath = transpath;
}
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 String getTranspath() {
return transpath;
}
public void setTranspath(String transpath) {
this.transpath = transpath;
}
@Override
public String toString() {
return "FileInfo{" +
"filename='" + filename + '\'' +
", filepath='" + filepath + '\'' +
", transpath='" + transpath + '\'' +
'}';
}
}文件处理类：fileHandle.class 该类实现了文件的下载和文件的删除功能
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
public class fileHandle extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
String action = req.getParameter("action");
if ("download".equals(action)) {
fileDownLoad(req, resp);
}
if ("delete".equals(action)) {
boolean b = fileDelete(req);
if (b) {
req.setAttribute("message", "文件删除成功");
}else {
req.setAttribute("message","文件删除失败");
}
req.getRequestDispatcher("success.jsp").forward(req, resp);
}
}
private synchronized boolean fileDelete(HttpServletRequest req) throws UnsupportedEncodingException {
String filepath = req.getParameter("path");
filepath = filepath.replace("%2F", File.separator);
File file = new File(filepath);
return file.delete();
}
/**
* System.out.println(System.getProperty("file.encoding")); //打印系统默认字符编码
* resp.addHeader("Content-Disposition", "attachment;filename=" + filename); //设置下载方式和文件名
* 注意此方法中文件名的编码格式是 ISO8859-1 所以需要使用 new String(filename.getBytes("UTF-8"),"ISO8859-1");将文件名进行转码
* 因为servlet设置了过滤器，所以请求的编码格式为 UTF-8 ，而系统的默认的字符编码为GBK，
* 所以要在控制台输出信息就需要使用 new String(str.getBytes("UTF-8"),"GBK");
*
* resp.setContentType("application/octet-stream"); //响应设置为二进制流
* resp.setContentType("application/multipart/form-data"); //设置文件ContentType类型，这样设置，会自动判断下载文件类型
*
*/
private synchronized void fileDownLoad(HttpServletRequest req, HttpServletResponse resp) throws IOException {
String filename = req.getParameter("name");
String filepath = req.getParameter("path");
filepath = filepath.replace("%2F", File.separator); //将路径中的路径符号重新转码为系统默认符号
resp.setCharacterEncoding("utf-8"); //设置响应编码
resp.setContentType("application/multipart/form-data"); //设置文件ContentType类型，这样设置，会自动判断下载文件类型
resp.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes("UTF-8"),"ISO8859-1")); //设置下载方式和文件名
File file = new File(filepath);
InputStream in = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(in); //读取服务器中的文件
BufferedOutputStream ous = new BufferedOutputStream(resp.getOutputStream()); //向客户端响应流文件
byte[] bytes = new byte[1024];
while (bis.read(bytes) != -1) {
ous.write(bytes);
ous.flush();
}
ous.close();
bis.close();
}
}在类中使用了servlet的响应流resp.getOutputStream()