SpringBoot 文件或图片上传与下载功能的实现

　<!-- 上传下载需要设计到的jar包 -->

<dependency>

  <groupId>commons-io</groupId>

  <artifactId>commons-io</artifactId>

  <version> 2.6 </version>

</dependency>

<dependency>

  <groupId>commons-fileupload</groupId>

  <artifactId>commons-fileupload</artifactId>

  <version> 1.3 . 3 </version>

</dependency>

<!--servlet-api导入高版本的-->

<dependency>

  <groupId>javax.servlet</groupId>

  <artifactId>javax.servlet-api</artifactId>

  <version> 4.0 . 1 </version>

</dependency>

<!-- 图片处理类 -->

<dependency>

  <groupId>net.coobird</groupId>

  <artifactId>thumbnailator</artifactId>

  <version> 0.4 . 8 </version>

</dependency>

# 上传文件大小

spring.servlet.multipart.max-file-size=5MB

spring.servlet.multipart.max-request-size=5MB

@Configuration

public class WebMvcConfig implements WebMvcConfigurer {

  @Override

  public void addResourceHandlers(ResourceHandlerRegistry registry) {

   ApplicationHome h = new ApplicationHome(getClass());

   File jarF = h.getSource();

   String dirPath = jarF.getParentFile().toString()+ "/upload/" ;

   String os = System.getProperty( "os.name" );

   if (os.toLowerCase().startsWith( "win" )) { //如果是Windows系统

    registry.addResourceHandler( "/upload/**" ).addResourceLocations( "file:" +dirPath);

   } else {

    registry.addResourceHandler( "/upload/**" ).addResourceLocations( "file:" +dirPath);

   }

  }

}

// 上传文件

  @ResponseBody

  @RequestMapping ( "/upload" )

  public String fileUpload( @RequestParam ( "files" ) MultipartFile files) throws IOException {

//  // win系统 上传路径保存设置

//  // 获取项目路径

//  File projectPath = new File(ResourceUtils.getURL("classpath:").getPath());

//  // 绝对路径=项目路径+自定义路径

//  File pathFile = new File(projectPath.getAbsolutePath(), "static/upload/");

//  if (!pathFile.exists()) {

//   pathFile.mkdirs();

//  }

//  //上传文件地址

//  UUID uuid = UUID.randomUUID();

//  File serverFile = new File(pathFile, uuid + "_" + files.getOriginalFilename());

//  files.transferTo(serverFile);

//

//  String imgPath = ("/upload/" + uuid + "_" + files.getOriginalFilename()).replace("\\", "/");

//

//  return imgPath;

   // Linux服务器 上传路径保存设置

   // 项目路径 /home/www/

   File pathFile = new File( "/home/www/upload/" );

   if (!pathFile.exists()) {

    pathFile.mkdirs();

   }

   //上传文件地址

   UUID uuid = UUID.randomUUID();

   File serverFile = new File(pathFile, uuid + "_" + files.getOriginalFilename());

   files.transferTo(serverFile);

   String imgPath = ( "/upload/" + uuid + "_" + files.getOriginalFilename()).replace( "\\" , "/" );

   return imgPath;

  }

<form action= "" class = "layui-form" enctype= "multipart/form-data" method= "post" >

　　<input type= "hidden" name= "blogImg" id= "imgPath" value= "" >

　　<div class = "form-group" >

　　　　<label>图片上传</label>

　　　　<input type= 'file' style= 'margin: 5px;' name= 'files' required><br>

　　　　<button type= "button" class = "layui-btn" id= "img_upload" >上传图片</button>

　　</div>

　　<input type= "submit" >

</form>

//普通图片上传

   $( '#img_upload' ).click(function () {

    var formData = new FormData();

    //获取选择的文件

    $.each($( 'input[name="files"]' ),function (index,item) {

     formData.append( "files" ,item.files[ 0 ])

    });

    //发送异步请求

    $.ajax({

     method: 'post' ,

     url: '[[@{/user/upload}]]' , // 文件上传接口

     data:formData,

     processData: false ,

     contentType: false ,

     success:function (data) {

      //成功返回触发的方法

      $( '#imgPath' ).val(data);

      alert( "上传成功" );

     },

     //请求失败触发的方法

     error:function () {

      alert( "上传失败" );

     }

    });

   });

@RequestMapping (value= "/download" )

public String downloads(HttpServletResponse response ,HttpServletRequest request) throws Exception{

  //要下载的图片地址

  String path = request.getServletContext().getRealPath( "/upload" );

  String fileName = "基础语法.jpg" ;

  //1、设置response 响应头

  response.reset(); //设置页面不缓存,清空buffer

  response.setCharacterEncoding( "UTF-8" ); //字符编码

  response.setContentType( "multipart/form-data" ); //二进制传输数据

  //设置响应头

  response.setHeader( "Content-Disposition" ,

    "attachment;fileName=" +URLEncoder.encode(fileName, "UTF-8" ));

  File file = new File(path,fileName);

  //2、 读取文件--输入流

  InputStream input= new FileInputStream(file);

  //3、 写出文件--输出流

  OutputStream out = response.getOutputStream();

  byte [] buff = new byte [ 1024 ];

  int index= 0 ;

  //4、执行 写出操作

  while ((index= input.read(buff))!= - 1 ){

   out.write(buff, 0 , index);

   out.flush();

  }

  out.close();

  input.close();

  return null ;

}

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