狂神 - javaweb - 文件上传

系统管理员 2023-02-10 03:56 3阅读 0赞

记录一下，以免以下几个包导错

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;

**源码：**

FileSerlvet类

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());
    		
    		// 判断上传的文件普通表单还是带文件的表单
    		if (!ServletFileUpload.isMultipartContent(request)) { 
    			return;//终止方法运行,说明这是一个普通的表单,直接返回
    		}
    	    //创建上传文件的保存路径,建议在WEB-INF路径下,安全,用户无法直接访间上传的文件;
    	    String uploadPath =this.getServletContext().getRealPath("/WEB-INF/upload");
    	    File uploadFile = new File(uploadPath);
    	    if (!uploadFile.exists()){ 
    	    uploadFile.mkdir(); //创建这个月录
    	    }
    		
    		// 创建上传文件的保存路径，建议在WEB-INF路径下，安全，用户无法直接访问上传的文件
    		String tmpPath = this.getServletContext().getRealPath("/WEB-INF/tmp");
    		File file = new File(tmpPath);
    		if (!file.exists()) { 
    			file.mkdir();//创建临时目录
    		}
    
    		// 处理上传的文件,一般都需要通过流来获取,我们可以使用 request, getInputstream(),原生态的文件上传流获取,十分麻烦
    		// 但是我们都建议使用 Apache的文件上传组件来实现, common-fileupload,它需要旅 commons-io组件;
    		try { 
    			// 创建DiskFileItemFactory对象，处理文件路径或者大小限制
    			DiskFileItemFactory factory = getDiskFileItemFactory(file);
    			/* * //通过这个工厂设置一个缓冲区,当上传的文件大于这个缓冲区的时候,将他放到临时文件 factory.setSizeThreshold(1024 * * 1024); //缓存区大小为1M factory.setRepository (file);//临时目录的保存目录,需要一个File */
    
    			// 2、获取ServletFileUpload
    			ServletFileUpload upload = getServletFileUpload(factory);
    
    			// 3、处理上传文件
    			// 把前端请求解析，封装成FileItem对象，需要从ServletFileUpload对象中获取
    			String msg = uploadParseRequest(upload, request, uploadPath);
    			
    			// Servlet请求转发消息
    			System.out.println(msg);
    			if(msg == "文件上传成功!") { 
    				// Servlet请求转发消息
    				request.setAttribute("msg",msg);
    				request.getRequestDispatcher("info.jsp").forward(request, response);
    			}else { 
    				msg ="请上传文件";
    				request.setAttribute("msg",msg);
    				request.getRequestDispatcher("info.jsp").forward(request, response);
    			}
    
    		} catch (FileUploadException e) { 
    			// TODO 自动生成的 catch 块
    			e.printStackTrace();
    		}
    	}
    
    	public static DiskFileItemFactory getDiskFileItemFactory(File file) { 
    		DiskFileItemFactory factory = new DiskFileItemFactory();
    		// 通过这个工厂设置一个缓冲区,当上传的文件大于这个缓冲区的时候,将他放到临时文件中;
    		factory.setSizeThreshold(1024 * 1024);// 缓冲区大小为1M
    		factory.setRepository(file);// 临时目录的保存目录,需要一个file
    		return factory;
    	}
    
    	public static ServletFileUpload getServletFileUpload(DiskFileItemFactory factory) { 
    		ServletFileUpload upload = new ServletFileUpload(factory);
    		// 监听长传进度
    		upload.setProgressListener(new ProgressListener() { 
    
    			// pBYtesRead:已读取到的文件大小
    			// pContextLength:文件大小
    			public void update(long pBytesRead, long pContentLength, int pItems) { 
    				System.out.println("总大小：" + pContentLength + "已上传：" + pBytesRead);
    			}
    		});
    
    		// 处理乱码问题
    		upload.setHeaderEncoding("UTF-8");
    		// 设置单个文件的最大值
    		upload.setFileSizeMax(1024 * 1024 * 10);
    		// 设置总共能够上传文件的大小
    		// 1024 = 1kb * 1024 = 1M * 10 = 10м
    
    		return upload;
    	}
    
    	public static String uploadParseRequest(ServletFileUpload upload, HttpServletRequest request, String uploadPath)
    			throws FileUploadException, IOException { 
    
    		String msg = "";
    		
    		// 把前端请求解析，封装成FileItem对象
    		List<FileItem> fileItems = upload.parseRequest(request);
    		for (FileItem fileItem : fileItems) { 
    			if (fileItem.isFormField()) { // 判断上传的文件是普通的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 { // 判断它是上传的文件
    				
    				// ============处理文件==============
    
    				// 拿到文件名
    				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/images/girl/paojie.png
    				String fileName = uploadFileName.substring(uploadFileName.lastIndexOf("/") + 1);
    				// 获得文件的后缀名
    				String fileExtName = uploadFileName.substring(uploadFileName.lastIndexOf(".") + 1);
    
    				/* * 如果文件后缀名fileExtName不是我们所需要的 就直按return.不处理,告诉用户文件类型不对。 */
    
    				System.out.println("文件信息[件名: " + fileName + " ---文件类型" + fileExtName + "]");
    				// 可以使用UID（唯一识别的通用码),保证文件名唯
    				// 0UID. randomUUID(),随机生一个唯一识别的通用码;
    				String uuidPath = UUID.randomUUID().toString();
    				
    				// ================处理文件完毕==============
    
    				// 存到哪? uploadPath
    				// 文件真实存在的路径realPath
    				String realPath = uploadPath + "/" + uuidPath;
    				// 给每个文件创建一个对应的文件夹
    				File realPathFile = new File(realPath);
    				if (!realPathFile.exists()) { 
    					realPathFile.mkdir();
    				}
    				// ==============存放地址完毕==============
    				
    				
    				// 获得文件上传的流
    				InputStream inputStream = fileItem.getInputStream();
    				// 创建一个文件输出流
    				// realPath =真实的文件夹;
    				// 差了一个文件;加上翰出文件的名产"/"+uuidFileName
    				FileOutputStream fos = new FileOutputStream(realPath + "/" + fileName);
    
    				// 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
    				//=============文件传输完成=============
    			}
    		}
    		return msg;
    
    	}
    }

注册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>

导入依赖的jar包

<dependency>
    			<groupId>commons-fileupload</groupId>
    			<artifactId>commons-fileupload</artifactId>
    			<version>1.4</version>
    		</dependency>
    	
    		<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：上传文件大小有限制
    		POST：上传文件大小没有限制
    		 ${pageContext.request.contextPath}
    		 --%>
    		<form action="upload.do" enctype="multipart/form-data" method="post">
    			上传用户：<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>