一、文件上传

1.1 导入pom依赖

 <commons-fileupload.version>1.3.3</commons-fileupload.version>
   
    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>${commons-fileupload.version}</version>
    </dependency>

1.2 配置文件上传解析器

在spring-mvc.xml文件中添加文件上传解析器。

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!-- 必须和用户JSP 的pageEncoding属性一致，以便正确解析表单的内容 -->
    <property name="defaultEncoding" value="UTF-8"></property>
    <!-- 文件最大大小(字节) 1024*1024*50=50M-->
    <property name="maxUploadSize" value="52428800"></property>
    <!--resolveLazily属性启用是为了推迟文件解析，以便捕获文件大小异常-->
    <property name="resolveLazily" value="true"/>
</bean>

这段代码是一个Spring框架的配置，用于处理文件上传功能。它定义了一个名为multipartResolver的Bean，使用org.springframework.web.multipart.commons.CommonsMultipartResolver类来处理文件上传。其中设置了默认的编码方式为UTF-8，文件的最大大小为50MB，并启用了懒解析模式。这段代码的作用是配置文件上传的相关参数。

1.3 设置文件上传表单

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <base href="${pageContext.request.contextPath }">
    <title>文件上传</title>
</head>
<body>
<form action="/file/upload" method="post" enctype="multipart/form-data">
    <label>编号：</label><input type="text" name="id" readonly="readonly" value="${param.id}"/><br/>
    <label>图片：</label><input type="file" name="imgFile"/><br/>
    <input type="submit" value="上传图片"/>
</form>
</body>
</html>

1.4 实现文件上传

（1） 设计表
在这里插入图片描述
(2) 配置generatorConfig.xml，并生成代码

   <table schema="" tableName="file_upload" domainObjectName="UploadFile"
               enableCountByExample="false" enableDeleteByExample="false"
               enableSelectByExample="false" enableUpdateByExample="false">
        </table>

（3） 创建业务层

（4） 配置resource.properties

#本地路径
dir=D:/upload/
#服务器路径
server=/upload/

(5) 配置文件读取工具类

package com.xqx.utils;
 
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
 

public class PropertiesUtil {
 
    public static String getValue(String key) throws IOException {
        Properties p = new Properties();
        InputStream in = PropertiesUtil.class.getResourceAsStream("/resource.properties");
        p.load(in);
        return p.getProperty(key);
    }
}

（6） 配置项目与映射地址
在这里插入图片描述
(7) 编写控制器

package com.xqx.web;
 
import com.xqx.biz.UploadFileBiz;
import com.xqx.model.UploadFile;
import com.xqx.utils.PageBean;
import com.xqx.utils.PropertiesUtil;
import org.apache.commons.io.FileUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;
 
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.util.List;
 

@Controller
@RequestMapping("/file")
public class UploadFileController {
    @Autowired
    private UploadFileBiz UploadFileBiz;
 
    /*新增方法*/
    @RequestMapping("/add")
    public String save(UploadFile UploadFile, HttpServletRequest request) {
        UploadFileBiz.insertSelective(UploadFile);
        return "redirect:list";
    }
 
    /*删除方法*/
    @RequestMapping("/del/{id}")
    public String del(@PathVariable("id") Integer id) {
        UploadFileBiz.deleteByPrimaryKey(id);
        return "redirect:/file/list";
    }
 
    /*修改方法*/
    @RequestMapping("/edit")
    public String edit(UploadFile UploadFile, HttpServletRequest request) {
        UploadFileBiz.updateByPrimaryKeySelective(UploadFile);
        return "redirect:list";
    }
 
    /*查询方法*/
    @RequestMapping("/list")
    public String list(UploadFile UploadFile, HttpServletRequest request) {
        PageBean pageBean = new PageBean();
        pageBean.setRequest(request);
        List<UploadFile> UploadFiles = UploadFileBiz.listPager(UploadFile, pageBean);
//        ModelAndView modelAndView = new ModelAndView();
//        modelAndView.addObject("UploadFiles", UploadFiles);
//        modelAndView.addObject("pageBean", pageBean);
//        modelAndView.setViewName("UploadFile/list");
        request.setAttribute("UploadFiles", UploadFiles);
        request.setAttribute("pageBean", pageBean);
        return "file/list";
    }
 
    /*数据回显*/
    @RequestMapping("/preSave")
    public String preSave(UploadFile UploadFile, HttpServletRequest request) {
        if (UploadFile != null && UploadFile.getId() != null && UploadFile.getId() != 0) {
            UploadFile img = UploadFileBiz.selectByPrimaryKey(UploadFile.getId());
            request.setAttribute("img", img);
        }
        return "file/edit";
    }
 
    /*图片上传*/
    @RequestMapping("upload")
    public String upload(UploadFile img,MultipartFile imgFile) throws IOException {
        //读取配置文夹本地路径和服务器路径
        String dir = PropertiesUtil.getValue("dir");
        String server = PropertiesUtil.getValue("server");
 
        //利用MultipartFile类接受前端传递到后台的文件
        System.out.println("文件名："+imgFile.getOriginalFilename());
        System.out.println("文件类型："+imgFile.getContentType());
 
        //将文件转成流写入到服务器
        FileUtils.copyInputStreamToFile(imgFile.getInputStream(),new File(dir+imgFile.getOriginalFilename()));
 
        //通过对象将图片保存到数据库
        img.setImg(server+imgFile.getOriginalFilename());
        UploadFileBiz.updateByPrimaryKeySelective(img);
 
        return "redirect:list";
    }
}

（8） 编写jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="w" uri="http://jsp.xqx.cn" %>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <link
            href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.css"
            rel="stylesheet">
    <script
            src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/js/bootstrap.js"></script>
    <base href="${pageContext.request.contextPath }">
    <title></title>
    <style type="text/css">
        .page-item input {
            padding: 0;
            width: 40px;
            height: 100%;
            text-align: center;
            margin: 0 6px;
        }
 
        .page-item input, .page-item b {
            line-height: 38px;
            float: left;
            font-weight: 400;
        }
 
        .page-item.go-input {
            margin: 0 10px;
        }
    </style>
</head>
<body>
<form class="form-inline"
      action="/file/list" method="post">
    <div class="form-group mb-2">
        <input type="text" class="form-control-plaintext" name="name"
               placeholder="请输入用户名称">
    </div>
    <button type="submit" class="btn btn-primary mb-2">查询</button>
    <a class="btn btn-primary mb-2" href="/file/preSave">新增</a>
</form>
 
<table class="table table-striped">
    <thead>
    <tr>
        <th scope="col">ID</th>
        <th scope="col">用户</th>
        <th scope="col">图片</th>
    </tr>
    </thead>
    <tbody>
    <c:forEach var="i" items="${uploadImgs }">
        <tr>
            <td>${i.id }</td>
            <td>${i.name }</td>
            <td>
                <img src="${i.img }" style="width: 200px;height: 100px;">
            </td>
            <td>
                <a href="/file/preSave?id=${i.id}">修改</a>
                <a href="/file/del/${i.id}">删除</a>
                <a href="/page/file/upload?id=${i.id}">图片上传</a>
                <a href="/file/download?id=${i.id}">图片下载</a>
            </td>
        </tr>
    </c:forEach>
    </tbody>
</table>
<!-- 这一行代码就相当于前面分页需求前端的几十行了 -->
<w:page pageBean="${pageBean }"></w:page>
 
</body>
</html>

在这里插入图片描述

二、文件下载

根据传入的文件id查询对应的文件信息，然后根据文件路径读取文件内容，并将文件内容和设置好的HTTP头信息封装成一个ResponseEntity对象，最后返回给客户端进行文件下载。

   @RequestMapping("/download")
    public ResponseEntity<byte[]> download(UploadImg uploadImg, HttpServletRequest req){
        try {
            //先根据文件id查询对应图片信息
            UploadImg img = this.uploadImgBiz.selectByPrimaryKey(uploadImg.getId());
            String diskPath = PropertiesUtil.getValue("dir");
            String reqPath = PropertiesUtil.getValue("server");
            //上面获取的数据库地址，需要转换才能下载成本地路径
            String realPath = img.getImg().replace(reqPath,diskPath);
            String fileName = realPath.substring(realPath.lastIndexOf("/")+1);
            //下载关键代码
            File file=new File(realPath);
            HttpHeaders headers = new HttpHeaders();//http头信息
            String downloadFileName = new String(fileName.getBytes("UTF-8"),"iso-8859-1");//设置编码
            headers.setContentDispositionFormData("attachment", downloadFileName);
            headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
            //MediaType:互联网媒介类型  contentType：具体请求中的媒体类型信息
            return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),headers, HttpStatus.OK);
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }

三、多文件上传

//多文件上传
    @RequestMapping("/uploads")
    public String uploads(HttpServletRequest req, Music music, MultipartFile[] files){
        try {
            StringBuffer sb = new StringBuffer();
            for (MultipartFile cfile : files) {
                //思路：
                //1) 将上传图片保存到服务器中的指定位置
                String dir = PropertiesUtil.getValue("dir");
                String server = PropertiesUtil.getValue("server");
                String filename = cfile.getOriginalFilename();
                FileUtils.copyInputStreamToFile(cfile.getInputStream(),new File(dir+filename));
                sb.append(filename).append(",");
            }
            System.out.println(sb.toString());
 
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "redirect:list";
    }