文件的上傳和下架功能（servlet）
上傳原理：
- 使用IO將文件存入指定文件夾，然後在數據庫中存入文件的絕對路徑
需要導入的依賴：
<!-- 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>
工具類
- 在工具類裏，我直接在文件處理的同時把文件的絕對路徑也添加到數據庫中
package com.lxs.util;
import com.lxs.pojo.Upload;
import com.lxs.service.UploadServiceImpl;
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.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.SQLException;
import java.util.List;
import java.util.UUID;
public class FileUtil {
public static DiskFileItemFactory gteDiskFileItemFactory(File file) {
//1、創建DiskFileItemFactory對象，處理文件上傳路徑或限制文件大小
DiskFileItemFactory factory = new DiskFileItemFactory();
//通過這個工廠設置一個緩衝區，當上傳的文件大小大於緩衝區的時候，將它放到我們的文件中；
factory.setSizeThreshold(1024 * 1024);//緩衝區大小爲1M
factory.setRepository(file);
return factory;
}
public static ServletFileUpload getServletFileUpload(DiskFileItemFactory factory) throws IOException {
//2、獲取ServletFileUpload
ServletFileUpload upload = new ServletFileUpload(factory);
return upload;
}
public static String uploadParseRequest(ServletFileUpload upload, HttpServletRequest request, String uploadpath) throws
IOException, FileUploadException, SQLException {
request.setCharacterEncoding("utf-8");
String msg = "文件上傳失敗";
//3、處理上傳文件
//把前端的請求解析，封裝成一個FileItem對象
List<FileItem> fileItems = upload.parseRequest(request);
for (FileItem fileItem : fileItems) {
if (fileItem.isFormField()) {
//判斷是普通表單還是帶文件的表單
//getFieldName指的是前端表單控件的name
String name = fileItem.getFieldName();
String value = fileItem.getString("UTF-8");//處理亂碼
System.out.println(name + ":" + value);
} else {//判斷它是帶文件的表單
//======================處理文件=======================//
//拿到文件的名字
String uploadFileName = fileItem.getName();
System.out.println("上傳的文件名：" + uploadFileName);
if (uploadFileName.trim().equals("") || uploadFileName == null) {
continue;
}
//獲得上傳的文件名，例如/img/lxs/123.jpg
String fileName = uploadFileName.substring(uploadFileName.lastIndexOf("/") + 1);
//獲得文件的後綴名
String fileExtName = uploadFileName.substring(uploadFileName.lastIndexOf(".") + 1);
System.out.println("文件信息【文件名：" + fileName + "文件類型：" + fileExtName + "】");
//可以使用UUID(唯一通用識別碼)來保證文件名的統一
String uuidFileName = UUID.randomUUID().toString();
//=======================傳輸文件=========================//
//獲得文件上傳的流
InputStream inputStream = fileItem.getInputStream();
//創建一個文件輸出流
String path=uploadpath + "/" + uuidFileName + "." + fileExtName;
FileOutputStream fos = new FileOutputStream(uploadpath + "/" + uuidFileName + "." + fileExtName);
//######################################################
//添加文件的路徑到數據庫
Upload up = new Upload();
UploadServiceImpl uploadService = new UploadServiceImpl();
up.setName(uuidFileName + "." + fileExtName);
System.out.println("aaaaa"+uploadFileName);
up.setPath(path);
System.out.println(path);
uploadService.addUpload(up);
//########################################################
//創建一個緩衝區
byte[] buffer = new byte[1024 * 1024];
//判斷是否讀取完畢
int len = 0;
//如果大於0，說明還存在數據
while ((len = inputStream.read(buffer)) > 0) {
fos.write(buffer, 0, len);
}
//關閉流
fos.close();
inputStream.close();
msg = "文件上傳成功！";
fileItem.delete();//上傳成功，清除臨時文件
}
}
return msg;
}
//刪除文件
public static void deleteFiles(File file){
if (file.isDirectory()) {
File[] files=file.listFiles();
for (int i = 0; i < files.length; i++) {
if (files[i].isDirectory()) {
deleteFiles(files[i]);
}else {
System.out.println("裏層文件："+files[i].getName()+"--------"+files[i].delete());
}
}
}
System.out.println("外層文件："+file.getName()+"--------"+file.delete());
}
}
FileServlet
package com.lxs.servlet;
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.sql.SQLException;
import com.lxs.util.FileUtil;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class FileServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws javax.servlet.ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
request.setCharacterEncoding("utf-8");
//判斷上傳的表單是普通表單還是帶文件的表單，是返回true,否返回false；
//如果這是一個普通文件我們直接返回
//如果通過了這個if，說明我們的表單是帶文件上傳的
if (!ServletFileUpload.isMultipartContent(request)) {
return;
}
//創建上傳文件的保存目錄，在WEB-INF目錄下是安全的，用戶無法訪問
/*String uploadpath = this.getServletContext().getRealPath("WEB-INF/Upload");*/
//獲取上傳文件的保存路徑
String uploadpath="D:/idea/Upload";
// File uploadfile = new File("D:/idea/Upload");
System.out.println(uploadpath);
File uploadfile = new File(uploadpath);
if (!uploadfile.exists()) {
uploadfile.mkdir();//如果目錄不存在就創建這樣一個目錄
}
try {
//1、創建DiskFileItemFactory對象，處理文件上傳路徑或限制文件大小
DiskFileItemFactory factory = FileUtil.gteDiskFileItemFactory(uploadfile);
//2、獲取ServletFileUpload
ServletFileUpload upload = FileUtil.getServletFileUpload(factory);
//3、處理上傳文件
String msg = FileUtil.uploadParseRequest(upload, request, uploadpath);
//Servlet請求轉發消息
request.setAttribute("msg", msg);
request.getRequestDispatcher("jsp/info.jsp").forward(request, response);
} catch (FileUploadException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
}