解決MultipartFile.transferTo(dest) 報FileNotFoundExcep的問題

Spring Upload file 報錯FileNotFoundException

環境:

  • Springboot 2.0.4
  • JDK8
  • 內嵌 Apache Tomcat/8.5.32

表單,enctype 和 input 的type=file 即可,例子使用單文件上傳

<form enctype="multipart/form-data" method="POST"
 action="/file/fileUpload">
 圖片<input type="file" name="file" />
 <input type="submit" value="上傳" />
</form>
@Controller
@RequestMapping("/file")
public class UploadFileController {
	@Value("${file.upload.path}")
	private String path = "upload/";

	@RequestMapping(value = "fileUpload", method = RequestMethod.POST)
	@ResponseBody
	public String fileUpload(@RequestParam("file") MultipartFile file) {
		if (file.isEmpty()) {
			return "false";
		}
		String fileName = file.getOriginalFilename();
		File dest = new File(path + "/" + fileName);
		if (!dest.getParentFile().exists()) { 
			dest.getParentFile().mkdirs();
		}
		try {
			file.transferTo(dest); // 保存文件
			return "true";
		} catch (Exception e) {
			e.printStackTrace();
			return "false";
		}
	}
}

運行在保存文件 file.transferTo(dest) 報錯

問題

dest 是相對路徑,指向 upload/doc20170816162034_001.jpg

file.transferTo 方法調用時,判斷如果是相對路徑,則使用temp目錄,為父目錄

因此,實際保存位置為 C:\Users\xxxx\AppData\Local\Temp\tomcat.372873030384525225.8080\work\Tomcat\localhost\ROOT\upload\doc20170816162034_001.jpg

一則,位置不對,二則沒有父目錄存在,因此產生上述錯誤。

解決辦法

transferTo 傳入參數 定義為絕對路徑

@Controller
@RequestMapping("/file")
public class UploadFileController {
	@Value("${file.upload.path}")
	private String path = "upload/";

	@RequestMapping(value = "fileUpload", method = RequestMethod.POST)
	@ResponseBody
	public String fileUpload(@RequestParam("file") MultipartFile file) {
		if (file.isEmpty()) {
			return "false";
		}
		String fileName = file.getOriginalFilename();
		File dest = new File(new File(path).getAbsolutePath()+ "/" + fileName);
		if (!dest.getParentFile().exists()) { 
			dest.getParentFile().mkdirs();
		}
		try {
			file.transferTo(dest); // 保存文件
			return "true";
		} catch (Exception e) {
			e.printStackTrace();
			return "false";
		}
	}
}

另外也可以 file.getBytes() 獲得字節數組,OutputStream.write(byte[] bytes)自己寫到輸出流中。

補充方法

application.properties 中增加配置項

spring.servlet.multipart.location= # Intermediate location of uploaded files.

關於上傳文件的訪問

1、增加一個自定義的ResourceHandler把目錄公佈出去

// 寫一個Java Config 
@Configuration
public class webMvcConfig implements org.springframework.web.servlet.config.annotation.WebMvcConfigurer{
	// 定義在application.properties
	@Value("${file.upload.path}")
	private String path = "upload/";
	public void addResourceHandlers(ResourceHandlerRegistry registry) {
		String p = new File(path).getAbsolutePath() + File.separator;//取得在服務器中的絕對路徑
		System.out.println("Mapping /upload/** from " + p);
		registry.addResourceHandler("/upload/**") // 外部訪問地址
			.addResourceLocations("file:" + p)// springboot需要增加file協議前綴
			.setCacheControl(CacheControl.maxAge(30, TimeUnit.MINUTES));// 設置瀏覽器緩存30分鐘
	}
}

application.properties 中 file.upload.path=upload/

實際存儲目錄

D:/upload/2019/03081625111.jpg

訪問地址(假設應用發佈在http://www.a.com/)

http://www.a.com/upload/2019/03081625111.jpg

2、在Controller中增加一個RequestMapping,把文件輸出到輸出流中

@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){
		// 通常上傳的文件會有一個數據表來存儲,這裡返回的id是記錄id
		UploadFile file = conversionService.convert(id, UploadFile.class);// 這步也可以寫在請求參數中
		if(file==null){
			throw new RuntimeException("沒有文件");
		}
		
		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;
	}
}

MultipartFile.transferTo(dest) 報找不到文件

今天使用transferTo這個方法進行上傳文件的使用發現瞭一些路徑的一些問題,查找瞭一下記錄問題所在

前端上傳網頁,使用的是單文件上傳的方式

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
</head>
<body>
    <form enctype="multipart/form-data" method="post" action="/upload">
        文件:<input type="file" name="head_img">
        姓名:<input type="text" name="name">
        <input type="submit" value="上傳">
    </form>
</body>
</html>

後臺網頁

@Controller
@RequestMapping("/file")
public class UploadFileController {
    @Value("${file.upload.path}")
    private String path = "upload/";
    @RequestMapping(value = "fileUpload", method = RequestMethod.POST)
    @ResponseBody
    public String fileUpload(@RequestParam("file") MultipartFile file) {
        if (file.isEmpty()) {
            return "false";
        }
        String fileName = file.getOriginalFilename();
        File dest = new File(path + "/" + fileName);
        if (!dest.getParentFile().exists()) { 
            dest.getParentFile().mkdirs();
        }
        try {
            file.transferTo(dest); // 保存文件
            return "true";
        } catch (Exception e) {
            e.printStackTrace();
            return "false";
        }
    }
}

這個確實存在一些問題

路徑是不對的

dest 是相對路徑,指向 upload/doc20170816162034_001.jpg

file.transferTo 方法調用時,判斷如果是相對路徑,則使用temp目錄,為父目錄

因此,實際保存位置為 C:\Users\xxxx\AppData\Local\Temp\tomcat.372873030384525225.8080\work\Tomcat\localhost\ROOT\upload\doc20170816162034_001.jpg

所以改為:

@Controller
@RequestMapping("/file")
public class UploadFileController {
    @Value("${file.upload.path}")
    private String path = "upload/";
    @RequestMapping(value = "fileUpload", method = RequestMethod.POST)
    @ResponseBody
    public String fileUpload(@RequestParam("file") MultipartFile file) {
        if (file.isEmpty()) {
            return "false";
        }
        String fileName = file.getOriginalFilename();
        File dest = new File(new File(path).getAbsolutePath()+ "/" + fileName);
        if (!dest.getParentFile().exists()) { 
            dest.getParentFile().mkdirs();
        }
        try {
            file.transferTo(dest); // 保存文件
            return "true";
        } catch (Exception e) {
            e.printStackTrace();
            return "false";
        }
    }
}

以上為個人經驗,希望能給大傢一個參考,也希望大傢多多支持WalkonNet。

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