一、如何实现文件上传

*上传*

1.文件上传，创建项目开发

2.创建UploadServlet类主要用于获取表单及其上传文件的信息

3.index.jsp页面的代码如下:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>


      
    
  
  
  	
    

    	名称： 

    	上传文件：

    	   
    	
    
    
  

二、文件上传的相关API

message.jsp代码:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>


  
    
  
  
   	
上传文件成功!
  

UploadServlet代码:

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.FileUtils;


public class UploadServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doPost(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		DiskFileItemFactory sf= new DiskFileItemFactory();//实例化磁盘被文件列表工厂
		String path = request.getRealPath("/upload");//得到上传文件的存放目录
		sf.setRepository(new File(path));//设置文件存放目录
		sf.setSizeThreshold(1024*1024);//设置文件上传小于1M放在内存中
		String rename = "";//文件新生成的文件名
		String fileName = "";//文件原名称
		String name = "";//普通field字段
		//从工厂得到servletupload文件上传类
		ServletFileUpload sfu = new ServletFileUpload(sf);
		
		try {
			List lst = sfu.parseRequest(request);//得到request中所有的元素
			for (FileItem fileItem : lst) {
				if(fileItem.isFormField()){
					if("name".equals(fileItem.getFieldName())){
						name = fileItem.getString("UTF-8");
					}
				}else{
					//获得文件名称
					fileName = fileItem.getName();
					fileName = fileName.substring(fileName.lastIndexOf("\")+1);
					String houzhui = fileName.substring(fileName.lastIndexOf("."));
					rename = UUID.randomUUID()+houzhui;
					fileItem.write(new File(path, rename));
				}
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		response.sendRedirect("message.jsp");
		out.flush();
		out.close();
	}
}

web的配置文件：

三、实现文件上传

上传页面：

文件上传成功：

四、实现文件下载

        前端实现下载代码：

                
    下载
    

    var excel_param;
    excel_param = {
        'start_time' : $("#start_time").val(),
        'end_time' : $("#end_time").val(),
        'order_uuids' : order_uuids
    };

    function download() {
        postDownLoadFile({
            url : '/ces/ces.do',
            data: excel_param,
            method : 'post'
        });
        $('#excel_modal').modal('hide');
    }

    var postDownLoadFile = function(options) {
        var config = $.extend(true, {
            method : 'post'
        }, options);
        var $iframe = $('