文件的上传

package com.chy.servlet;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
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.util.List;

/** 用来处理文件上传数据
 * @author Snickerman
 * @create 2021-04-24 14:38
 * @Description
 */
public class UploadServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        System.out.println("文件上传过来了");
        //客户端以流的形式发送，不能用原来的getParameter()来接受
//        ServletInputStream inputStream = req.getInputStream();
//
//        byte[] buffer = new byte[1024];
//        int read = inputStream.read(buffer);
//        System.out.println(new String(buffer,0,read));

        //1.判断上传的数据是否是多段数据(只有是多段的数据，才是文件上传的)
        if(ServletFileUpload.isMultipartContent(req)){
            //创建 FileItemFactory工厂实现类
            FileItemFactory fileItemFactory = new DiskFileItemFactory();
            //创建用于解析上传数据的工具类ServletFileUpload类
            ServletFileUpload servletFileUpload = new ServletFileUpload(fileItemFactory);

            try {
                List<FileItem> list = servletFileUpload.parseRequest(req);
            //循环判断每一个表单项，是普通类型还是上传的文件
                for (FileItem fileItem : list){
                    if (fileItem.isFormField()){
                        //普通表单项
                        System.out.println("表单项的name属性值"+fileItem.getFieldName());
                        //参数UTF-8解决乱码问题
                        System.out.println("表单项的value属性值" + fileItem.getString("UTF-8"));

                    }else{
                        //上传的文件
                        System.out.println("表单项的name属性值" + fileItem.getFieldName());
                        System.out.println("上传的文件名" + fileItem.getName());

                        try {
                            fileItem.write(new File("e:\\" + fileItem.getName()));
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                }

            } catch (FileUploadException e) {
                e.printStackTrace();
            }
        }

    }

}