SpringMVC如何实现文件的上传和下载 详细代码解析

月亮捕捞者 2021-08-11 10:43:02 浏览数 (2421)
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本文实例为大家分享了SpringMVC实现文件上传与下载的具体代码，供大家参考，具体内容如下

0.环境准备

1.maven依赖

<dependencies>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-api</artifactId>
      <version>5.7.0</version>
      <scope>test</scope>
    </dependency>


    <!-- servlet依赖 -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>

    <!-- springMVC依赖 -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.6.RELEASE</version>
    </dependency>

    <!-- 文件上传的jar包 -->
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.8.0</version>
    </dependency>
    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>1.3.3</version>
</dependency>

2.springConfig。xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       https://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <!-- 开启组件扫描   -->
    <context:component-scan base-package="com.compass.file"></context:component-scan>

    <!--声明 配置springMVC视图解析器-->
    <bean  class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--前缀：视图文件的路径-->
        <property name="prefix" value="/WEB-INF/view/" />
        <!--后缀：视图文件的扩展名-->
        <property name="suffix" value=".jsp" />
    </bean>

    <!--读写JSON的支持（Jackson）-->
    <mvc:annotation-driven />

<!--  配置多媒体解析  -->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!--  配置字符编码集 -->
        <property name="defaultEncoding" value="utf-8"> </property>
<!-- 配置文件上传大小 单位是字节    -1代表没有限制 maxUploadSizePerFile是限制每个上传文件的大小，而maxUploadSize是限制总的上传文件大小  -->
        <property name="maxUploadSizePerFile" value="-1"> </property>

 <!-- ，不设置默认不限制总的上传文件大小，这里设置总的上传文件大小不超过1M（1*1024*1024） -->
        <property name="maxUploadSize" value="1048576"/>

    </bean>

</beans>

3.web.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
  <!-- 声明springMvc的核心对象 DispatcherServlet -->
  <servlet>
    <servlet-name>web</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springConfig.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>web</servlet-name>
    <url-pattern>*.mvc</url-pattern>
  </servlet-mapping>

  <!--  注册字符集过滤器,解决post请求的中文乱码问题-->
  <filter>
    <filter-name>characterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>utf-8</param-value>
    </init-param>
    <init-param>
      <param-name>forRequestEncoding</param-name>
      <param-value>true</param-value>
    </init-param>
    <init-param>
      <param-name>forResponseEncoding</param-name>
      <param-value>true</param-value>
    </init-param>

  </filter>
  <filter-mapping>
    <filter-name>characterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

1.文件上传

文件上传分为三种方式：

  • 单个文件单字段
  • 多个文件单字段
  • 多个文件多字段

注意点：

1、提交方式为表单的post请求
2、from属性中必须有enctype=“multipart/form-data”
3、如果是单字段多文件：输入框中的属性必须为：multiple=“multiple”
4、表单中的属性name必须和后端参数一致

1.前端代码

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>文件上传</title>
</head>
<body>

<div>
    <p style="text-align: center">文件上传（单个文件单字段上传）</p>
    <form action="${pageContext.request.contextPath}/uploadFile1.mvc" method="post"  enctype="multipart/form-data">
        <input type="file" name="file">
        <input type="submit" value="提交">
    </form>
</div>

<div>
    <p style="text-align: center">文件上传（多文件单字段上传）</p>
    <form action="${pageContext.request.contextPath}/uploadFile2.mvc" method="post"  enctype="multipart/form-data">
        <input type="file" name="file" multiple="multiple">
        <input type="submit" value="提交">
    </form>
</div>


<div>
    <p style="text-align: center">文件上传（多文件多字段上传）</p>
    <form action="${pageContext.request.contextPath}/uploadFile2.mvc" method="post"  enctype="multipart/form-data">
        <input type="file" name="file" >
        <input type="file" name="file" >
        <input type="submit" value="提交">
    </form>
</div>

</body>
</html>

2.后端代码

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpSession;
import java.io.File;
import java.io.IOException;

/**
 * @author compass
 * @version 1.0
 * @date 2021-05-11 14:33
 */
@Controller
public class UploadIFileController {

    // 处理单个文件上传
    @PostMapping("/uploadFile1.mvc")
     public ModelAndView uploadFile1(MultipartFile file, HttpSession session) throws IOException {

        ModelAndView view = new ModelAndView();
        // 得到文件名称
        String filename=file.getOriginalFilename();
        System.out.println("文件名称："+filename);
        if (!file.isEmpty()){
            // 判断文件的后缀
            if (filename.endsWith(".jpg")||filename.endsWith(".png")||filename.endsWith(".txt"));
            //设置文件的保存路径
            String savePath="C:\Users\14823\IdeaProjects\springMVC\fileupload\src\main\webapp\WEB-INF\file";
            File srcFile = new File(savePath,filename);
            // 执行文件保存操作
            file.transferTo(srcFile);
            view.setViewName("forward:/uploadSuccess.jsp");
        }else {
            view.setViewName("forward:/uploadFailed.jsp");
        }
        return view;
    }

    // 处理多文件上传
    @PostMapping("/uploadFile2.mvc")
    public ModelAndView uploadFile2(MultipartFile[] file,HttpSession session) throws IOException {

        ModelAndView view = new ModelAndView();
        //设置文件的保存路径
        String savePath="C:\Users\14823\IdeaProjects\springMVC\fileupload\src\main\webapp\WEB-INF\file";
        String[] filenames = new String[file.length];
        // 只要上传过来的文件为空或者是不符合指定类型的都会上传失败
        for (int i = 0; i <filenames.length ; i++) {
            // 判断上传过来的文件是否为空
            if (!file[i].isEmpty()){
               String filename=file[i].getOriginalFilename();
               // 判断文件类型
               if (filename.endsWith(".txt")||filename.endsWith(".jpg")||filename.endsWith(".png")){
                   // 创建一个文件对象
                   File srcFile = new File(savePath, filename);
                   // 执行保存文件操作
                   file[i].transferTo(srcFile);
                   view.setViewName("forward:/uploadSuccess.jsp");
               }else {
                   view.setViewName("forward:/uploadSuccess.jsp");
               }

            }else {
                view.setViewName("forward:/uploadFailed.jsp");
            }

        }
        return view;
    }
}

2.文件下载

文件下分为两种情况：

  • 文件名称是纯英文字母的
  • 文件名带有中文不处理会乱码的

1.前端代码

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>文件下载</title>
</head>
<body>
<h1 style="text-align: center"><a href="${pageContext.request.contextPath}/download1.mvc?filename=preview.jpg" rel="external nofollow" >文件下载(非中文名称)</a></h1>
<h1 style="text-align: center"><a href="${pageContext.request.contextPath}/download2.mvc?filename=文件下载.txt" rel="external nofollow" >文件下载(中文名称)</a></h1>
</body>
</html>

2.后端代码

/**
 * @author compass
 * @version 1.0
 * @date 2021-05-11 15:23
 */
@Controller
public class DownloadController {

    // 非中文名称文件下载
    @GetMapping("/download1.mvc")
    public ResponseEntity <byte[]> fileDownload1(String filename,HttpServletRequest request) throws IOException {

        String path="C:\Users\14823\IdeaProjects\springMVC\fileupload\src\main\webapp\WEB-INF\file\";
        File file = new File(path,filename);
        HttpHeaders header = new HttpHeaders();
        header.setContentDispositionFormData("attachment",filename);
        header.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        ResponseEntity<byte[]> result = new ResponseEntity<>(FileUtils.readFileToByteArray(file), header, HttpStatus.OK);
        return result;
    }

    // 中文名称文件下载
    @GetMapping("/download2.mvc")
    public ResponseEntity <byte[]> fileDownload2(String filename,HttpServletRequest request) throws IOException {

        System.out.println(filename);
        String path="C:\Users\14823\IdeaProjects\springMVC\fileupload\src\main\webapp\WEB-INF\file\";
        filename = filename.replace("_", "%");
        filename= URLDecoder.decode(filename,"UTF-8");
        String downloadFile="";
        if (request.getHeader("USER-AGENT").toLowerCase().indexOf("msie")>0){
            filename= URLEncoder.encode(filename,"UTF-8");
            downloadFile=filename.replaceAll("+","%20");
        }else {
            downloadFile=new String(filename.getBytes("UTF-8"),"ISO-8859-1");
        }
        File file = new File(path,filename);
        HttpHeaders header = new HttpHeaders();
        header.setContentDispositionFormData("attachment",downloadFile);
        header.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        ResponseEntity<byte[]> result = new ResponseEntity<>(FileUtils.readFileToByteArray(file), header, HttpStatus.OK);
        return result;
    }

}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持W3Cschool。


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