使用Fileupload实现文件的上传（上传到本地）

 
        
            javax.servlet
            javax.servlet-api
            4.0.1
            provided
        
        
            org.junit.jupiter
            junit-jupiter-api
            ${junit.version}
            test
        
        
            org.junit.jupiter
            junit-jupiter-engine
            ${junit.version}
            test
        

        
            javax.servlet.jsp
            jsp-api
            2.2
        

        
            org.apache.taglibs
            taglibs-standard-spec
            1.2.1
        
        
            org.apache.taglibs
            taglibs-standard-impl
            1.2.1
        



        
            commons-fileupload
            commons-fileupload
            1.3.1
        
        
            commons-io
            commons-io
            2.4
        

    

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

import javax.servlet.ServletException;
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;

public class UploadServlet extends HttpServlet {
    //用来处理文件上传
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        //isMultipartContent这个方法返回true表示有文件的上传，false为普通表单
        if (ServletFileUpload.isMultipartContent(req)) {
            //创建FileItemFactory工厂的实现类.
            FileItemFactory fileItemFactory = new DiskFileItemFactory();
            //创建用于解析上传的工具类ServletFileUpload
            ServletFileUpload servletFileUpload = new ServletFileUpload(fileItemFactory);
            try {
                //解析上传的数据，得到每一个表单项FileItem
                List list = servletFileUpload.parseRequest(req);
                //循环判断每一个表单项是普通表单还是上传的文件
                for (FileItem fileItem : list) {
                    if (fileItem.isFormField()) {
                        System.out.println("表单项name属性：" + fileItem.getFieldName());
                        //参数UTF-8解决乱码问题
                        System.out.println("表单项value属性：" + fileItem.getString("UTF-8"));
                    } else {
                        //上传的文件
                        System.out.println("表单项name属性：" + fileItem.getFieldName());
                        System.out.println("上传的文件名：" + fileItem.getName());
                        fileItem.write(new File("c:\idea\" + fileItem.getName()));
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }
}