MultipartFile中transferTo(File file)的路径问题及解决

<!-- 定义文件上传解析器 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!-- 设定默认编码 -->
    <property name="defaultEncoding" value="UTF-8"></property>
    <!-- 设定文件上传的最大值为5MB，5*1024*1024 -->
    <property name="maxUploadSize" value="5242880"></property>
    <!-- 设定文件上传时写入内存的最大值，如果小于这个参数不会生成临时文件，默认为10240 -->
    <property name="maxInMemorySize" value="40960"></property>
    <!-- 上传文件的临时路径 -->
    <property name="uploadTempDir" value="fileUpload/temp"></property>
    <!-- 延迟文件解析 -->
    <property name="resolveLazily" value="true"/>
</bean>

@ResponseBody
    @RequestMapping("/upload")
    public Map upload(HttpServletRequest request,MultipartFile file){
        HashMap<String,String> map=new HashMap();
        if (!file.isEmpty()) {
            try {
                // getOriginalFilename()是包含源文件后缀的全名
                String filePath = "D:/upload/test/"+file.getOriginalFilename();
                System.out.println(filePath);
                File saveDir = new File(filePath);
                if (!saveDir.getParentFile().exists())
                    saveDir.getParentFile().mkdirs();
                file.transferTo(saveDir);
                map.put("res","上传成功");
                return map;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        map.put("res","上传失败");
        return map;
    }

String filePath = "D:/upload/test/"+file.getOriginalFilename();

String filePath = "D:/upload/test";

<form enctype="multipart/form-data" method="POST"
    action="/file/fileUpload">
    图片<input type="file" name="file" />
    <input type="submit" value="上传" />
</form>

@PostMapping("/upload")
@ResponseBody
public Map<String, Object> upload(HttpServletRequest httpServletRequest){
    boolean flag = false;
    MultipartHttpServletRequest multipartHttpServletRequest = null;
    //强制转换为MultipartHttpServletRequest接口对象 (它包含所有HttpServletRequest的方法)
    if(httpServletRequest instanceof MultipartHttpServletRequest){
        multipartHttpServletRequest = (MultipartHttpServletRequest) httpServletRequest;
    }else{
        return dealResultMap(false, "上传失败");
    }
    //获取MultipartFile文件信息(注意参数为前端对应的参数名称)
    MultipartFile mf = multipartHttpServletRequest.getFile("file");
    //获取源文件名称
    String fileName = mf.getOriginalFilename();
    //存储路径可在配置文件中指定
    File pfile = new File("D:/fileupload1/");
    if (!pfile.exists()) {
        pfile.mkdirs();
    }
    File file = new File(pfile,  fileName);
   
    try {
        //保存文件
        //使用此方法保存必须要绝对路径且文件夹必须已存在,否则报错
        mf.transferTo(file);
    } catch (IOException e) {
        e.printStackTrace();
        return dealResultMap(false, "上传失败");
    }
    return dealResultMap(true, "上传成功");
}

@PostMapping("/upload/MultipartFile")
@ResponseBody
public Map<String, Object> uploadMultipartFile(@RequestParam("file") MultipartFile multipartFile){
    String fileName = multipartFile.getOriginalFilename();
    try {
        //获取文件字节数组
        byte [] bytes = multipartFile.getBytes();
        //文件存储路径(/fileupload1/ 这样会在根目录下创建问价夹)
        File pfile = new File("/fileupload1/");
        //判断文件夹是否存在
        if(!pfile.exists()){
            //不存在时,创建文件夹
            pfile.mkdirs();
        }
        //创建文件
        File file = new File(pfile, fileName);
        //写入指定文件夹
        OutputStream out = new FileOutputStream(file);
        out.write(bytes);
    } catch (IOException e) {
        e.printStackTrace();
        return dealResultMap(false, "上传失败");
    }
    
    return dealResultMap(true, "上传成功");
}
@PostMapping("/upload/part")
@ResponseBody
public Map<String, Object> uploadPart(@RequestParam("file") Part part){
    System.out.println(part.getSubmittedFileName());
    System.out.println(part.getName());
    //输入流
    InputStream inputStream = null;
    try {
        inputStream = part.getInputStream();
    } catch (IOException e) {
        e.printStackTrace();
        return dealResultMap(false, "上传失败");
    }
    //保存到临时文件
    //1K的数据缓冲流
    byte[] bytes = new byte[1024];
    //读取到的数据长度
    int len;
    //输出的文件保存到本地文件
    File pfile = new File("/fileupload1/");
    if (!pfile.exists()) {
        pfile.mkdirs();
    }
    File file = new File(pfile, part.getSubmittedFileName());
    OutputStream out;
    try {
        out = new FileOutputStream(file);
        //开始读取
        while ((len = inputStream.read(bytes)) != -1){
            out.write(bytes, 0, len);
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        return dealResultMap(false, "上传失败");
    } catch (IOException e) {
        e.printStackTrace();
        return dealResultMap(false, "上传失败");
    }
    
    return dealResultMap(true, "上传成功");
}

//1.使用此方法保存必须指定盘符（在系统配置时要配绝对路径）;
      // 也可以通过 File f = new File(new File(path).getAbsolutePath()+ "/" + fileName); 取得在服务器中的绝对路径 保存即可
//      file.transferTo(f);
      //2.使用此方法保存可相对路径（/var/falcon/）也可绝对路径（D:/var/falcon/）
      byte [] bytes = file.getBytes();
      OutputStream out = new FileOutputStream(f);
      out.write(bytes);

// 写一个Java Config 
@Configuration
public class webMvcConfig implements org.springframework.web.servlet.config.annotation.WebMvcConfigurer{
    // 定义在application.properties
    @Value("${file.upload.path}")
    private String path = "upload/";
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        String p = new File(path).getAbsolutePath() + File.separator;//取得在服务器中的绝对路径
        System.out.println("Mapping /upload/** from " + p);
        registry.addResourceHandler("/upload/**") // 外部访问地址
            .addResourceLocations("file:" + p)// springboot需要增加file协议前缀
            .setCacheControl(CacheControl.maxAge(30, TimeUnit.MINUTES));// 设置浏览器缓存30分钟
    }
}

@RestController
@RequestMapping("/file")
public class UploadFileController {
    @Autowired
    protected HttpServletRequest request;
    @Autowired
    protected HttpServletResponse response;
    @Autowired
    protected ConversionService conversionService;
    @Value("${file.upload.path}")
    private String path = "upload/";    
    @RequestMapping(value="/view", method = RequestMethod.GET)
    public Object view(@RequestParam("id") Integer id){
        // 通常上传的文件会有一个数据表来存储，这里返回的id是记录id
        UploadFile file = conversionService.convert(id, UploadFile.class);// 这步也可以写在请求参数中
        if(file==null){
            throw new RuntimeException("没有文件");
        }
        
        File source= new File(new File(path).getAbsolutePath()+ "/" + file.getPath());
        response.setContentType(contentType);
        try {
            FileCopyUtils.copy(new FileInputStream(source), response.getOutputStream());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}