解決MultipartFile.transferTo(dest) 報(bào)FileNotFoundExcep的問(wèn)題

更新時(shí)間：2021年07月01日 10:47:13 作者：dany_zj_cn

這篇文章主要介紹了解決MultipartFile.transferTo(dest) 報(bào)FileNotFoundExcep的問(wèn)題，具有很好的參考價(jià)值，希望對(duì)大家有所幫助。如有錯(cuò)誤或未考慮完全的地方，望不吝賜教

Spring Upload file 報(bào)錯(cuò)FileNotFoundException

環(huán)境：

Springboot 2.0.4
JDK8
內(nèi)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(yùn)行在保存文件 file.transferTo(dest) 報(bào)錯(cuò)

問(wèn)題

dest 是相對(duì)路徑，指向 upload/doc20170816162034_001.jpg

file.transferTo 方法調(diào)用時(shí)，判斷如果是相對(duì)路徑，則使用temp目錄，為父目錄

因此，實(shí)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(duì)，二則沒(méi)有父目錄存在，因此產(chǎn)生上述錯(cuò)誤。

解決辦法

transferTo 傳入?yún)?shù) 定義為絕對(duì)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(jié)數(shù)組，OutputStream.write(byte[] bytes)自己寫(xiě)到輸出流中。

補(bǔ)充方法

application.properties 中增加配置項(xiàng)

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

關(guān)于上傳文件的訪問(wèn)

1、增加一個(gè)自定義的ResourceHandler把目錄公布出去

// 寫(xiě)一個(gè)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(wù)器中的絕對(duì)路徑
		System.out.println("Mapping /upload/** from " + p);
		registry.addResourceHandler("/upload/**") // 外部訪問(wèn)地址
			.addResourceLocations("file:" + p)// springboot需要增加file協(xié)議前綴
			.setCacheControl(CacheControl.maxAge(30, TimeUnit.MINUTES));// 設(shè)置瀏覽器緩存30分鐘
	}
}

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

實(shí)際存儲(chǔ)目錄

D:/upload/2019/03081625111.jpg

訪問(wèn)地址（假設(shè)應(yīng)用發(fā)布在http://www.a.com/）

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

2、在Controller中增加一個(gè)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(huì)有一個(gè)數(shù)據(jù)表來(lái)存儲(chǔ)，這里返回的id是記錄id
		UploadFile file = conversionService.convert(id, UploadFile.class);// 這步也可以寫(xiě)在請(qǐng)求參數(shù)中
		if(file==null){
			throw new RuntimeException("沒(méi)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(bào)找不到文件

今天使用transferTo這個(gè)方法進(jìn)行上傳文件的使用發(fā)現(xiàn)了一些路徑的一些問(wèn)題，查找了一下記錄問(wèn)題所在

前端上傳網(wǎng)頁(yè)，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>

后臺(tái)網(wǎng)頁(yè)

@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(gè)確實(shí)存在一些問(wèn)題

路徑是不對(duì)的

dest 是相對(duì)路徑，指向 upload/doc20170816162034_001.jpg

file.transferTo 方法調(diào)用時(shí)，判斷如果是相對(duì)路徑，則使用temp目錄，為父目錄

因此，實(shí)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(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。

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