Javaweb实现文件上传
JavaWeb实现文件上传
- 首先配置文件上传的jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>文件上传</title> </head> <body> <%-- method 必须是post get没法得到大数据的文件 enctype="multipart/form-data" 表示表单中存在上传数据 --%> <form action="${pageContext.request.contextPath}/file" enctype="multipart/form-data" method="post"> <p>上传用户：<input type="text" name="userName"></p> <p>选择文件：<input type="file" name="uploadFile"></p> <p><input type="submit"></p> </form> </body> </html>
- 配置index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>$Title$</title> </head> <body> <a href="${pageContext.request.contextPath}/fileup.jsp">上传文件</a> </body> </html>
- 配置文件上传的servlet
import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.FileUploadException; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; import javax.servlet.http.HttpServletRequest; import java.io.*; import java.util.List; import java.util.UUID; public class UpLoadServlet extends javax.servlet.http.HttpServlet { protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException { doGet(request, response); } protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException { //判断上传的文件是普通的文本表单仍是文件表单 //若是是文件表单则返回true,这里取反，说明是普通表单 if (!ServletFileUpload.isMultipartContent(request)) { return; } //若是if为false，则说明咱们的表单是带文件上传的 //建立一个上传文件的保存路径 建议在WEB-INF路径下 安全，用户没法直接访问上传的文件 String uploadPath = this.getServletContext().getRealPath("/WEB-INF/upload"); File file1 = new File(uploadPath); if (!file1.exists()){ file1.mkdir(); } //加入文件超过预期大小，咱们把它放到一个临时文件中，过几天自动删除 或者提示用户保存永久 String tmpPath = this.getServletContext().getRealPath("/WEB-INF/tmp"); File file2 = new File(tmpPath); if (!file2.exists()) { file2.mkdir(); } //处理上传的文件，经过工厂来获取 DiskFileItemFactory factory = getDiskFileItemFactory(file2); //获取ServletFileUpload对象 文件上传解析器 ServletFileUpload upload = getServletFileUpload(factory); //把前端请求解析，封装成一个FileItem对象 try { //得到文件上传是否成功的消息 String msg = getMSG(uploadPath,upload,request); request.setAttribute("msg",msg); request.getRequestDispatcher("info.jsp").forward(request,response); } catch (FileUploadException e) { e.printStackTrace(); } } public DiskFileItemFactory getDiskFileItemFactory(File file) { //处理上传的文件 //1. 建立一个DiskFileItemFactory对象 DiskFileItemFactory factory = new DiskFileItemFactory(); //2.设置缓冲区，当上传的文件大于缓冲区时，放到临时文件中 factory.setSizeThreshold(1024 * 1024);//1MB //3.设置临时目录的保存文件 factory.setRepository(file); return factory; } public ServletFileUpload getServletFileUpload(DiskFileItemFactory factory) { ServletFileUpload upload = new ServletFileUpload(factory); //监听文件上传进度 upload.setProgressListener((long l, long l1, int i)-> { System.out.println("总大小：" + l1 + "已上传" + l); } ); //设置文件编码格式，防止乱码 upload.setHeaderEncoding("utf-8"); //设置单个文件的最大值 upload.setFileSizeMax(1024 * 1024);//1MB //设置总共能上传文件的大小 upload.setSizeMax(1024 * 1024 * 10);//10MB return upload; } public String getMSG(String uploadPath, ServletFileUpload upload, HttpServletRequest request) throws IOException, FileUploadException { String msg = ""; List<FileItem> list = upload.parseRequest(request); for (FileItem fileItem : list) { //判断是文件仍是表单 if (fileItem.isFormField()) { //得到上传文件的用户名字 getFieldName指的是前端表单控件的name String name = fileItem.getFieldName(); //将上传文件用户的名字的编码格式改成utf-8，防止乱码 String value = fileItem.getString("utf-8"); System.out.println(name + ":" + value); } else { //拿到文件名 String fileName = fileItem.getName(); System.out.println("上传的文件名：" + fileName); if (fileName.trim().equals("") || fileName == null) { msg = "文件不存在，没法保存"; return msg;//文件不存在 没法保存 } //得到文件名 web/resources/1.png String name = fileName.substring(fileName.lastIndexOf("/") + 1); //得到文件后缀 String fileExtName = fileName.substring(fileName.lastIndexOf(".") + 1); System.out.println("文件名：" + name + "文件类型" + fileExtName); //防止图片名字重复 UUID（惟一识别的） String uuidFileName = UUID.randomUUID().toString() + "_" + name; //文件真实存在的路径 String realPath = uploadPath + "/" + uuidFileName; //给路径建立一个文件夹 File realPathFile = new File(realPath); if (!realPathFile.exists()) { realPathFile.mkdir(); } //[================================================ //得到文件上传的流 InputStream inputStream = fileItem.getInputStream(); //用流写入文件中 FileOutputStream fos = new FileOutputStream(realPath+"/"+name); byte[] b = new byte[1024]; int len = 0; while ((len = inputStream.read(b)) != -1) { fos.write(b, 0, len); } msg = "文件上传成功！"; //关闭流 fos.close(); inputStream.close(); } } return msg; } }
- 配置上传成功的jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>上传成功</title> </head> <body> <h1> ${msg} </h1> </body> </html>
- 配置web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> <servlet> <servlet-name>UpLoadServlet</servlet-name> <servlet-class>com.baidu.servlet.UpLoadServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>UpLoadServlet</servlet-name> <url-pattern>/file</url-pattern> </servlet-mapping> </web-app>
用tomcat把项目跑一遍，再查看out路径下，就会有你上传的文件
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