文件上传

文件上传：
 ???????文件上传，对流操作
 ???????将文件通过表单上传到服务器，服务器从request中将文件读取到输入流
 ???????在将输入流中的数据 通过输出流写入目的文件夹下即可

 ???????javaweb项目的lib文件夹 应该创建在web---- WEB-INF

 ???????fileupload：文件上传
 ???????commons-io：通用的io相关的工具jar包

 ??文件上传的步骤
 ???????????1、创建fileupload.html
 ???????????2、创建fileuploadServlet
 ???????????3、导入jar包
 ???????????4、编码

 ???????fileuplaod.html:
 ????????????注意：
 ???????????????1、文件上传请求方式只能用post
 ???????????????2、enctype="multipart/form-data"

 ???????fileuploadservlet:
 ???????见代码

 ?上传了的文件 如何访问？
 ??????1、配置tomcat虚拟路径
 ???????????<Context docBase="E:\file" ?path="/upload"/>
 ???????2、通过idea设置tomcat 勾选Deploy……

例如：
封装类：

public class FileUtils {

 ???/**
 ????* 获取真实的文件名
 ????* @param name
 ????* @return
 ????*/
 ???public static String getRealFileName(String name){
 ???????int index = name.lastIndexOf("\\");
 ???????return name.substring(index+1);
 ???}

 ???/**
 ????* 生成文件名
 ????* @param name
 ????* @return
 ????*/
 ???public static String getUUIDFileName(String name){
 ???????UUID uuid = UUID.randomUUID();
 ???????String s = uuid.toString().replaceAll("-", "");
 ???????return s+name;
 ???}
}

上传类：

@WebServlet(value = "/fileUploadServlet",name = "FileUploadServlet")
public class FileUploadServlet extends HttpServlet {
 ???protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 ???????//1、设置编码格式
 ???????request.setCharacterEncoding("utf-8");
 ???????response.setContentType("text/html;charset=utf-8");
 ???????//2、创建文件上传核心对象DiskFileItemFactory
 ???????DiskFileItemFactory factory = new DiskFileItemFactory();
 ???????//3、文件上传对象
 ???????ServletFileUpload upload = new ServletFileUpload(factory);
 ???????//设置相关参数
 ???????upload.setHeaderEncoding("utf-8");//防止中文名乱码
 ???????upload.setFileSizeMax(1024*1024*5);//单位：b
 ???????//4、解析request，将请求中的数据封装成FileItem
 ???????try {
 ???????????List<FileItem> list = upload.parseRequest(request);
 ???????????//遍历集合解析数据
 ???????????for (FileItem item : list) {
 ???????????????if(item.isFormField()){//普通字段

 ???????????????}else{//表示是文件
 ???????????????????//文件上传
 ???????????????????//获取文件名
 ???????????????????String filename = item.getName();

 ???????????????????filename = FileUtils.getRealFileName(filename);
 ???????????????????filename = FileUtils.getUUIDFileName(filename);
 ???????????????????//确定存储路径
 ???????????????????String filepath = "E:\\file";
 ???????????????????File file = new File(filepath);
 ???????????????????if(!file.exists()){
 ???????????????????????file.mkdirs();
 ???????????????????}
 ???????????????????//拼接上传路径
 ???????????????????filepath = filepath+File.separator+filename;
 ???????????????????System.out.println(filepath);
 ???????????????????//获取输入流
 ???????????????????InputStream in = item.getInputStream();
 ???????????????????//获取输出流
 ???????????????????FileOutputStream out = new FileOutputStream(filepath);
 ???????????????????//复制
 ???????????????????IOUtils.copy(in, out);
 ???????????????????out.close();
 ???????????????????in.close();
 ???????????????}
 ???????????}
 ???????} catch (Exception e) {
 ???????????e.printStackTrace();
 ???????}

 ???}

 ???protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 ???????doPost(request,response );
 ???}
}

文件上传

原文地址：https://www.cnblogs.com/wzhsc/p/10326630.html