文件批量上传获取不到 spring boot springboot文件上传进度

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jowvid 2023-10-24 11:38:20

文章标签 java 文件上传 spring 自定义 文章分类 spring boot 后端开发

本功能基于commons fileUpload 组件实现

首先，不能在程序中直接使用 fileUpload.parseRequest（request）的方式来获取 request 请求中的 multipartFile 文件对象，原因是因为在 spring 默认的文件上传处理器 multipartResolver 指向的类CommonsMultipartResolver 中就是通过 commons fileUpload 组件实现的文件获取，因此，在代码中再次使用该方法，是获取不到文件对象的，因为此时的 request 对象是不包含文件的，它已经被CommonsMultipartResolver 类解析处理并转型。

思考：

1、文件上传的过程其处理逻辑是怎样的？

看CommonsMultipartResolver转化请求的一段过程：

/**
	 * Parse the given servlet request, resolving its multipart elements.
	 * @param request the request to parse
	 * @return the parsing result
	 * @throws MultipartException if multipart resolution failed.
	 */
	protected MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException {
		String encoding = determineEncoding(request);
		FileUpload fileUpload = prepareFileUpload(encoding);
		try {
			List<FileItem> fileItems = ((ServletFileUpload) fileUpload).parseRequest(request);
			return parseFileItems(fileItems, encoding);
		}
		catch (FileUploadBase.SizeLimitExceededException ex) {
			throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex);
		}
		catch (FileUploadBase.FileSizeLimitExceededException ex) {
			throw new MaxUploadSizeExceededException(fileUpload.getFileSizeMax(), ex);
		}
		catch (FileUploadException ex) {
			throw new MultipartException("Failed to parse multipart servlet request", ex);
		}
	}

由于spring 中的 CommonsMultipartResolver 类中并没有加入 processListener 文件上传进度监听器，所以，直接使用 CommonsMultipartResolver 类是无法监听文件上传进度的，如果我们需要获取文件上传进度，就需要继承 CommonsMultipartResolver 类并重写 parseRequest 方法。

添加监听该监听器后，上传组件在上传文件的时会不断回调该方法，回传这些数据。利用这些数字，就可以计算出文件上传的进度，用进度条实时显示出来。

在此之前，我们需要创建一个实现了 processListener 接口的实现类用于监听文件上传进度。

UploadProcessListener接口实现类：

import javax.servlet.http.HttpSession;

import org.apache.commons.fileupload.ProgressListener;
import org.springframework.stereotype.Component;

@Component
public class UploadProgressListener implements ProgressListener {
    private HttpSession session;

    public void setSession(HttpSession session){
        this.session=session;
        ProgressEntity status = new ProgressEntity();
        session.setAttribute("status", status);
    }

    /* pBytesRead  到目前为止读取文件的比特数
     * pContentLength 文件总大小
     * pItems 目前正在读取第几个文件
     */
    public void update(long pBytesRead, long pContentLength, int pItems) {
        ProgressEntity status = (ProgressEntity) session.getAttribute("status");
        status.setPBytesRead(pBytesRead);
        status.setPContentLength(pContentLength);
        status.setPItems(pItems);
        System.out.println("UploadProgressListener update ProgressEntity:  "+status.toString());
    }
}

ProgressEntity 实体类：

@Component
public class ProgressEntity {
    // 读取的文件的比特数
    private long pBytesRead = 0L;
    // 文件的总大小
    private long pContentLength = 0L;
    // 目前正在读取第几个文件
    private int pItems;

    private long startTime = System.currentTimeMillis();

    public ProgressEntity() {
        pBytesRead = 0L;
        pContentLength = 0L;
    }

    public long getPBytesRead() {
        return pBytesRead;
    }

    public void setPBytesRead(long bytesRead) {
        pBytesRead = bytesRead;
    }

    public long getPContentLength() {
        return pContentLength;
    }

    public void setPContentLength(long contentLength) {
        pContentLength = contentLength;
    }

    public int getPItems() {
        return pItems;
    }

    public void setPItems(int items) {
        pItems = items;
    }

    @Override
    public String toString() {
        float tmp = (float) pBytesRead;
        float result = tmp / pContentLength * 100;
        return "ProgressEntity [pBytesRead=" + pBytesRead + ", pContentLength="
                + pContentLength + ", percentage=" + result + "% , pItems=" + pItems + "]";
    }
}

最后，是继承 CommonsMultipartResolver 类的自定义文件上传处理类：

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUpload;
import org.apache.commons.fileupload.FileUploadBase;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.multipart.MaxUploadSizeExceededException;
import org.springframework.web.multipart.MultipartException;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;

public class CustomMultipartResolver extends CommonsMultipartResolver {

    @Autowired
    private UploadProgressListener uploadProgressListener;

    @Override
    protected MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException {
        String encoding = determineEncoding(request);
        FileUpload fileUpload = prepareFileUpload(encoding);


        uploadProgressListener.setSession(request.getSession());// 文件上传进度监听器设置session用于存储上传进度
        fileUpload.setProgressListener(uploadProgressListener);// 将文件上传进度监听器加入到 fileUpload 中
        try {
            List<FileItem> fileItems = ((ServletFileUpload) fileUpload).parseRequest(request);
            return parseFileItems(fileItems, encoding);
        } catch (FileUploadBase.SizeLimitExceededException ex) {
            throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex);
        } catch (FileUploadBase.FileSizeLimitExceededException ex) {
            throw new MaxUploadSizeExceededException(fileUpload.getFileSizeMax(), ex);
        } catch (FileUploadException ex) {
            throw new MultipartException("Failed to parse multipart servlet request", ex);
        }
    }
}

此时，所有需要的类已经准备好，接下来我们需要将 spring 默认的文件上传处理类取消自动配置，并将 multipartResolver 指向我们刚刚创建好的继承 CommonsMultipartResolver 类的自定义文件上传处理类。

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.multipart.MultipartResolver;

import com.baidu.doclabel.biz.listener.CustomMultipartResolver;


/*
 * exclude表示将 spring 默认的MultipartAutoConfiguration文件上传处理类取消自动配置
 * 注意：这里自定义了文件处理类，不加exclude，也会走我们自定义的
 */
// @EnableAutoConfiguration(exclude = {MultipartAutoConfiguration.class})
@EnableAutoConfiguration
@Configuration
public class UploadProgressApplication {
   // 将 multipartResolver 指向我们刚刚创建好的继承 CommonsMultipartResolver 类的 自定义文件上传处理类
    @Bean(name = "multipartResolver")
    public MultipartResolver multipartResolver() {
        CustomMultipartResolver customMultipartResolver = new CustomMultipartResolver();
        return customMultipartResolver;
    }
}

至此，准备工作完成，我们再创建一个测试用的 controller

@Slf4j
@Controller
@Api(tags = {"文件上传test"})
@RequestMapping("/label/file/upload/test")
public class FileUploadController {

    @RequestMapping(value = "/upload", method = {RequestMethod.POST})
    public GenericBaseResponse useAbility(@Valid AbilityUseFileUpload request) {
        log.info("AbilityController getAbility, request={}", request);
        return new GenericBaseResponse(DoclabelErrorCode.SUCCESS);
    }
}

其中AbilityUseFileUpload类中有个参数是：private List<MultipartFile> multipartFileList;

项目启动：

注意下面我把自定义的multipartResolver又写了一遍，如果这个地方有写一遍的话，上面就不用定义UploadProgressApplication这个类了，如果想把启动类和定义的bean分开，只需要把下面这个方法的启动和定义multipartResolver这个bean分开就行。

/*
 * exclude表示将 spring 默认的MultipartAutoConfiguration文件上传处理类取消自动配置
 * 注意：这里自定义了文件处理类，不加exclude，也会走我们自定义的
 */
// @EnableAutoConfiguration(exclude = {MultipartAutoConfiguration.class})
@EnableAutoConfiguration
@Configuration
@ComponentScan("com.example")
@EnableDiscoveryClient
public class ApplicationRunner {
    public static void main(String[] args) {
        SpringApplication.run(ApplicationRunner.class, args);
    }


@Bean(name = "multipartResolver")
public MultipartResolver multipartResolver() {
	CustomMultipartResolver customMultipartResolver = new CustomMultipartResolver();
	return customMultipartResolver;
}

}

我是通过postman做的debug测试：

看到控制台输出的结果：

文件批量上传获取不到 spring boot springboot文件上传进度_spring