工程目录结构

 

完整代码：

 

1、pom.xml

首先当然是添加依赖，用到thymeleaf模板渲染html页面

       
      
       4.0.0
        
      
       com.hello
        
      
       HelloBoot
        
      
       0.0.1-SNAPSHOT
        
      
       jar
        
          
       
        UTF-8
         
          
          
       
        org.springframework.boot
           
       
        spring-boot-starter-parent
           
       
        2.0.1.BUILD-SNAPSHOT
         
          
          
               
        
         org.springframework.boot
                
        
         spring-boot-starter-web
            
               
               
        
         org.springframework.boot
                
        
         spring-boot-starter-thymeleaf
            
         
          
          
               
        
         spring-snapshots
                
        
         Spring Snapshots
                
        
         https://repo.spring.io/libs-snapshot
                
                    
         
          true
                 
            
         
        
     

 

如果遇到<parent>标签报错，看看和上面写的有出入吗---

 

2、application.properties

只有一行，关闭thymeleaf缓存

spring.thymeleaf.cache=false

 

 

3、file.html 页面

         
文件上传
    
     
        
      
        
      
            
     
    下载

 

 

4、HelloController.java  控制类

 

package com.hello;import java.io.BufferedInputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.OutputStream;import javax.servlet.http.HttpServletResponse;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.ResponseBody;import org.springframework.web.multipart.MultipartFile;@Controllerpublic class HelloController {    //映射视图    @RequestMapping("/file")    public String file() {        return "/file";    }        //上传    @RequestMapping("fileUpload")    @ResponseBody    public String fileUpload(@RequestParam("filename") MultipartFile file) {        if(file.isEmpty()) {            return "false";        }        //将里面内容移动到目标文本文档        File dest = new File("D:/test.txt");        try {            file.transferTo(dest);         } catch (IllegalStateException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        return "success";    }    //下载    @RequestMapping("fileDownload")    @ResponseBody    public String fileDownload(HttpServletResponse res) {        String fileName = "1.jpg";        res.setHeader("content-type", "application/octet-stream");        res.setContentType("application/octet-stream");        res.setHeader("Content-Disposition", "attachment;filename=" + fileName);                byte[] buff = new byte[1024];        BufferedInputStream bis = null;        OutputStream os = null;        try {            os = res.getOutputStream();            //获取zhi'ding            bis = new BufferedInputStream(                    new FileInputStream(new File("D:/1.jpg")));            int i = bis.read(buff);            while(i != -1) {                //每次读取1024字节，就flush输出                os.write(buff, 0, buff.length);                os.flush();                //然后继续读取下一个1024字节                i = bis.read(buff);            }                    } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } finally {              if (bis != null) {                  try {                    bis.close();                  } catch (IOException e) {                    e.printStackTrace();                  }                }        }        return "success";    }        }

 

 

（1）file()方法return返回的是视图“file.html”，使用@Controller修饰类即可

（2）上传业务方法fileUpload()，return返回的是个字符串——“false“或”success”，不是html视图页面，所以不用渲染视图，

这里使用@Controller修饰类    和    @ResponseBody修饰方法

 

5、启动类App.java

package com.hello;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class App {    public static void main(String[] args) {        SpringApplication.run(App.class, args);    }}