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java后臺本地文件轉(zhuǎn)為MultipartFile類型的實現(xiàn)方式

更新時間：2025年02月13日 09:35:20 作者：探索途中的碼農(nóng)

在Java后臺將本地文件轉(zhuǎn)換為MultipartFile類型,可以通過使用FileItemFactory創(chuàng)建FileItem,然后使用CommonsMultipartFile類構(gòu)造一個MultipartFile對象,將本地文件流轉(zhuǎn)換為MultipartFile,getMultipartFiles()和getMultipartFiles()方法

java后臺本地文件轉(zhuǎn)為MultipartFile類型

前端上傳文件轉(zhuǎn)為MultipartFile類型，java后臺通過springmvc接收自動轉(zhuǎn)換處理就不用多說了。

現(xiàn)在需要在后臺java代碼里將本地文件轉(zhuǎn)換為MultipartFile類型如何處理呢？

如下代碼

主要利用FileItemFactory創(chuàng)建FileItem，MultipartFile的實現(xiàn)類CommonsMultipartFile構(gòu)造一個對象，將本地讀取的文件流轉(zhuǎn)換為MultipartFile。

getMultipartFiles()和getMultipartFiles（）支持一個文件的轉(zhuǎn)換和多個文件的轉(zhuǎn)換。

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.MediaType;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.commons.CommonsMultipartFile;
 
import java.io.*;
 
public class MultipartFileTest {
 
    private static final Logger log = LoggerFactory.getLogger(MultipartFileTest.class);
 
    private MultipartFileTest() { }
 
 
    public static void main(String[] args) {
        // 本地文件轉(zhuǎn)為MultipartFile類型
        try{
            InputStream fis = new FileInputStream("E:\\tool\\20230102word.doc");
            MultipartFileTest.getMultipartFile(fis, "20230102word.doc");
        }catch (FileNotFoundException e){
            log.error("FileNotFoundException exception", e);
            throw new RuntimeException("文件不存在");
        }
    }
 
    public static MultipartFile getMultipartFile(InputStream inputStream, String fileName) {
        FileItem fileItem = createFileItem(inputStream, fileName);
        return new CommonsMultipartFile(fileItem);
    }
 
 
    public static MultipartFile[] getMultipartFiles(InputStream[] inputStream, String fileName) {
        // 多文件轉(zhuǎn)換
        int length = inputStream.length;
        MultipartFile[] multipartFiles = new MultipartFile[length];
        for (int i = 0; i < length; i++) {
            FileItem fileItem = createFileItem(inputStream[i], fileName);
            multipartFiles[i] = new CommonsMultipartFile(fileItem);
        }
        return multipartFiles;
    }
 
 
    public static FileItem createFileItem(InputStream inputStream, String fileName) {
        FileItemFactory factory = new DiskFileItemFactory(16, null);
        FileItem fileItem = factory.createItem("file", MediaType.MULTIPART_FORM_DATA_VALUE, true, fileName);
        int read = 0;
        OutputStream os = null;
        byte[] buffer = new byte[10 * 1024 * 1024];
        try {
            os = fileItem.getOutputStream();
            while ((read = inputStream.read(buffer, 0, 4096)) != -1) {
                os.write(buffer, 0, read);
            }
            inputStream.close();
        } catch (IOException e) {
            log.error("os write exception", e);
            throw new IllegalArgumentException("文件流輸出失敗");
        } finally {
            if (os != null) {
                try {
                    os.close();
                } catch (IOException e) {
                    log.error("stream os close exception", e);
                }
            }
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    log.error("stream inputStream close exception", e);
                }
            }
        }
        return fileItem;
    }
}