文件的上传和下架功能（servlet）
上传原理：
- 使用IO将文件存入指定文件夹，然后在数据库中存入文件的绝对路径
需要导入的依赖：
<!-- 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>
工具类
- 在工具类里，我直接在文件处理的同时把文件的绝对路径也添加到数据库中
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、创建DiskFileItemFactory对象，处理文件上传路径或限制文件大小
DiskFileItemFactory factory = new DiskFileItemFactory();
//通过这个工厂设置一个缓冲区，当上传的文件大小大于缓冲区的时候，将它放到我们的文件中；
factory.setSizeThreshold(1024 * 1024);//缓冲区大小为1M
factory.setRepository(file);
return factory;
}
public static ServletFileUpload getServletFileUpload(DiskFileItemFactory factory) throws IOException {
//2、获取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 = "文件上传失败";
//3、处理上传文件
//把前端的请求解析，封装成一个FileItem对象
List<FileItem> fileItems = upload.parseRequest(request);
for (FileItem fileItem : fileItems) {
if (fileItem.isFormField()) {
//判断是普通表单还是带文件的表单
//getFieldName指的是前端表单控件的name
String name = fileItem.getFieldName();
String value = fileItem.getString("UTF-8");//处理乱码
System.out.println(name + ":" + value);
} else {
//判断它是带文件的表单
//======================处理文件=======================//
//拿到文件的名字
String uploadFileName = fileItem.getName();
System.out.println("上传的文件名：" + uploadFileName);
if (uploadFileName.trim().equals("") || uploadFileName == null) {
continue;
}
//获得上传的文件名，例如/img/lxs/123.jpg
String fileName = uploadFileName.substring(uploadFileName.lastIndexOf("/") + 1);
//获得文件的后缀名
String fileExtName = uploadFileName.substring(uploadFileName.lastIndexOf(".") + 1);
System.out.println("文件信息【文件名：" + fileName + "文件类型：" + fileExtName + "】");
//可以使用UUID(唯一通用识别码)来保证文件名的统一
String uuidFileName = UUID.randomUUID().toString();
//=======================传输文件=========================//
//获得文件上传的流
InputStream inputStream = fileItem.getInputStream();
//创建一个文件输出流
String path=uploadpath + "/" + uuidFileName + "." + fileExtName;
FileOutputStream fos = new FileOutputStream(uploadpath + "/" + uuidFileName + "." + fileExtName);
//######################################################
//添加文件的路径到数据库
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);
//########################################################
//创建一个缓冲区
byte[] buffer = new byte[1024 * 1024];
//判断是否读取完毕
int len = 0;
//如果大于0，说明还存在数据
while ((len = inputStream.read(buffer)) > 0) {
fos.write(buffer, 0, len);
}
//关闭流
fos.close();
inputStream.close();
msg = "文件上传成功！";
fileItem.delete();//上传成功，清除临时文件
}
}
return msg;
}
//删除文件
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("里层文件："+files[i].getName()+"--------"+files[i].delete());
}
}
}
System.out.println("外层文件："+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");
//判断上传的表单是普通表单还是带文件的表单，是返回true,否返回false；
//如果这是一个普通文件我们直接返回
//如果通过了这个if，说明我们的表单是带文件上传的
if (!ServletFileUpload.isMultipartContent(request)) {
return;
}
//创建上传文件的保存目录，在WEB-INF目录下是安全的，用户无法访问
/*String uploadpath = this.getServletContext().getRealPath("WEB-INF/Upload");*/
//获取上传文件的保存路径
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();//如果目录不存在就创建这样一个目录
}
try {
//1、创建DiskFileItemFactory对象，处理文件上传路径或限制文件大小
DiskFileItemFactory factory = FileUtil.gteDiskFileItemFactory(uploadfile);
//2、获取ServletFileUpload
ServletFileUpload upload = FileUtil.getServletFileUpload(factory);
//3、处理上传文件
String msg = FileUtil.uploadParseRequest(upload, request, uploadpath);
//Servlet请求转发消息
request.setAttribute("msg", msg);
request.getRequestDispatcher("jsp/info.jsp").forward(request, response);
} catch (FileUploadException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
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