【狂神說Java】JavaWeb-檔案上傳
阿新 • • 發佈：2020-08-23
記錄一下，以免以下幾個包導錯
import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.FileUploadException; import org.apache.commons.fileupload.ProgressListener; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload;
原始碼：
FileSerlvet類
package com.chen; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.List; import java.util.UUID; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.FileUploadException; import org.apache.commons.fileupload.ProgressListener; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; /** * Servlet implementation class FileSerlvet */ public class FileSerlvet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse * response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub // response.getWriter().append("Served at: ").append(request.getContextPath()); // 判斷上傳的檔案普通表單還是帶檔案的表單 if (!ServletFileUpload.isMultipartContent(request)) { return;//終止方法執行,說明這是一個普通的表單,直接返回 } //建立上傳檔案的儲存路徑,建議在WEB-INF路徑下,安全,使用者無法直接訪間上傳的檔案; String uploadPath =this.getServletContext().getRealPath("/WEB-INF/upload"); File uploadFile = new File(uploadPath); if (!uploadFile.exists()){ uploadFile.mkdir(); //建立這個月錄 } // 建立上傳檔案的儲存路徑，建議在WEB-INF路徑下，安全，使用者無法直接訪問上傳的檔案 String tmpPath = this.getServletContext().getRealPath("/WEB-INF/tmp"); File file = new File(tmpPath); if (!file.exists()) { file.mkdir();//建立臨時目錄 } // 處理上傳的檔案,一般都需要通過流來獲取,我們可以使用 request, getInputstream(),原生態的檔案上傳流獲取,十分麻煩 // 但是我們都建議使用 Apache的檔案上傳元件來實現, common-fileupload,它需要旅 commons-io元件; try { // 建立DiskFileItemFactory物件，處理檔案路徑或者大小限制 DiskFileItemFactory factory = getDiskFileItemFactory(file); /* * //通過這個工廠設定一個緩衝區,當上傳的檔案大於這個緩衝區的時候,將他放到臨時檔案 factory.setSizeThreshold(1024 * * 1024); //快取區大小為1M factory.setRepository (file);//臨時目錄的儲存目錄,需要一個File */ // 2、獲取ServletFileUpload ServletFileUpload upload = getServletFileUpload(factory); // 3、處理上傳檔案 // 把前端請求解析，封裝成FileItem物件，需要從ServletFileUpload物件中獲取 String msg = uploadParseRequest(upload, request, uploadPath); // Servlet請求轉發訊息 System.out.println(msg); if(msg == "檔案上傳成功!") { // Servlet請求轉發訊息 request.setAttribute("msg",msg); request.getRequestDispatcher("info.jsp").forward(request, response); }else { msg ="請上傳檔案"; request.setAttribute("msg",msg); request.getRequestDispatcher("info.jsp").forward(request, response); } } catch (FileUploadException e) { // TODO 自動生成的 catch 塊 e.printStackTrace(); } } public static DiskFileItemFactory getDiskFileItemFactory(File file) { DiskFileItemFactory factory = new DiskFileItemFactory(); // 通過這個工廠設定一個緩衝區,當上傳的檔案大於這個緩衝區的時候,將他放到臨時檔案中; factory.setSizeThreshold(1024 * 1024);// 緩衝區大小為1M factory.setRepository(file);// 臨時目錄的儲存目錄,需要一個file return factory; } public static ServletFileUpload getServletFileUpload(DiskFileItemFactory factory) { ServletFileUpload upload = new ServletFileUpload(factory); // 監聽長傳進度 upload.setProgressListener(new ProgressListener() { // pBYtesRead:已讀取到的檔案大小 // pContextLength:檔案大小 public void update(long pBytesRead, long pContentLength, int pItems) { System.out.println("總大小：" + pContentLength + "已上傳：" + pBytesRead); } }); // 處理亂碼問題 upload.setHeaderEncoding("UTF-8"); // 設定單個檔案的最大值 upload.setFileSizeMax(1024 * 1024 * 10); // 設定總共能夠上傳檔案的大小 // 1024 = 1kb * 1024 = 1M * 10 = 10м return upload; } public static String uploadParseRequest(ServletFileUpload upload, HttpServletRequest request, String uploadPath) throws FileUploadException, IOException { String msg = ""; // 把前端請求解析，封裝成FileItem物件 List<FileItem> fileItems = upload.parseRequest(request); for (FileItem fileItem : fileItems) { if (fileItem.isFormField()) {// 判斷上傳的檔案是普通的表單還是帶檔案的表單 // getFieldName指的是前端表單控制元件的name; String name = fileItem.getFieldName(); String value = fileItem.getString("UTF-8"); // 處理亂碼 System.out.println(name + ": " + value); } else {// 判斷它是上傳的檔案 // ============處理檔案============== // 拿到檔名 String uploadFileName = fileItem.getName(); System.out.println("上傳的檔名: " + uploadFileName); if (uploadFileName.trim().equals("") || uploadFileName == null) { continue; } // 獲得上傳的檔名/images/girl/paojie.png String fileName = uploadFileName.substring(uploadFileName.lastIndexOf("/") + 1); // 獲得檔案的字尾名 String fileExtName = uploadFileName.substring(uploadFileName.lastIndexOf(".") + 1); /* * 如果檔案字尾名fileExtName不是我們所需要的 就直按return.不處理,告訴使用者檔案型別不對。 */ System.out.println("檔案資訊[件名: " + fileName + " ---檔案型別" + fileExtName + "]"); // 可以使用UID（唯一識別的通用碼),保證檔名唯 // 0UID. randomUUID(),隨機生一個唯一識別的通用碼; String uuidPath = UUID.randomUUID().toString(); // ================處理檔案完畢============== // 存到哪? uploadPath // 檔案真實存在的路徑realPath String realPath = uploadPath + "/" + uuidPath; // 給每個檔案建立一個對應的資料夾 File realPathFile = new File(realPath); if (!realPathFile.exists()) { realPathFile.mkdir(); } // ==============存放地址完畢============== // 獲得檔案上傳的流 InputStream inputStream = fileItem.getInputStream(); // 建立一個檔案輸出流 // realPath =真實的資料夾; // 差了一個檔案;加上翰出文件的名產"/"+uuidFileName FileOutputStream fos = new FileOutputStream(realPath + "/" + fileName); // 建立一個緩衝區 byte[] buffer = new byte[1024 * 1024]; // 判斷是否讀取完畢 int len = 0; // 如果大於0說明還存在資料; while ((len = inputStream.read(buffer)) > 0) { fos.write(buffer, 0, len); } // 關閉流 fos.close(); inputStream.close(); msg = "檔案上傳成功!"; fileItem.delete(); // 上傳成功,清除臨時檔案 //=============檔案傳輸完成============= } } return msg; } }
註冊xml
<servlet>
<servlet-name>upload</servlet-name>
<servlet-class>com.chen.FileSerlvet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>upload</servlet-name>
<url-pattern>/upload.do</url-pattern>
匯入依賴的jar包
<!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload --> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.4</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-io/commons-io --> <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.6</version> </dependency>
index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
<%--
GET：上傳檔案大小有限制
POST：上傳檔案大小沒有限制
${pageContext.request.contextPath}
--%>
<form action="upload.do" enctype="multipart/form-data" method="post">
上傳使用者：<input type="text" name="username"><br/>
<P><input type="file" name="file1"></P>
<P><input type="file" name="file1"></P>
<P><input type="submit" value="提交"> | <input type="reset"></P>
</form>
</body>
</html>
info.jsp
<%@ page language="java" contentType="text/html;charset=UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<title>Insert title here</title>
</head>
<body>
<%=request.getAttribute("msg")%>
</body>
</html>