import org.springframework.mock.web.MockMultipartFile;
import org.springframework.web.multipart.MultipartFile;

public class MultipartFileConverter {
    
    public static MultipartFile convertUsingMock(byte[] fileBytes, String fileName) {
        // 假設(shè)已知確切的 ContentType，例如 "image/png"
        // 如果不確定，可使用 APPLICATION_OCTET_STREAM
        return new MockMultipartFile(
            "file",                    // 表單字段名
            fileName,                  // 原始文件名
            "image/png",               // 內(nèi)容類型 (Content-Type)
            fileBytes                  // 文件的字節(jié)數(shù)組
        );
    }
    
    // 使用示例
    public static void main(String[] args) {
        byte[] myFileBytes = getFileBytesSomehow(); // 您的字節(jié)數(shù)組來(lái)源
        String fileName = "example.png";
        
        MultipartFile multipartFile = convertUsingMock(myFileBytes, fileName);
        
        System.out.println("文件名: " + multipartFile.getOriginalFilename());
        System.out.println("文件大小: " + multipartFile.getSize() + " 字節(jié)");
    }
}

<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.4</version> <!-- 請(qǐng)檢查并使用最新版本 -->
</dependency>

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItem;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.commons.CommonsMultipartFile;

import java.io.*;

public class MultipartFileUtils {

    public static MultipartFile convertBytesToMultipartFile(byte[] fileBytes, String fileName, String contentType) throws IOException {
        // 創(chuàng)建臨時(shí)文件項(xiàng)
        FileItem fileItem = createFileItem(fileName, contentType);
        
        // 將字節(jié)數(shù)組寫入文件項(xiàng)的輸出流
        try (OutputStream os = fileItem.getOutputStream()) {
            os.write(fileBytes);
        }
        
        // 使用 CommonsMultipartFile 包裝 FileItem
        return new CommonsMultipartFile(fileItem);
    }
    
    private static FileItem createFileItem(String fileName, String contentType) {
        // 使用 DiskFileItemFactory 創(chuàng)建 FileItem
        // 參數(shù)說(shuō)明：fieldName, contentType, isFormField, fileName
        return new DiskFileItem("file", contentType, false, fileName);
    }
}

import org.springframework.web.multipart.MultipartFile;
import java.io.*;

public class CustomMultipartFile implements MultipartFile {
    
    private final byte[] fileContent;
    private final String originalFilename;
    private final String contentType;
    
    public CustomMultipartFile(byte[] fileContent, String originalFilename, String contentType) {
        this.fileContent = fileContent != null ? fileContent : new byte[0];
        this.originalFilename = originalFilename;
        this.contentType = contentType;
    }
    
    @Override
    public String getName() {
        return "file";
    }
    
    @Override
    public String getOriginalFilename() {
        return this.originalFilename;
    }
    
    @Override
    public String getContentType() {
        return this.contentType;
    }
    
    @Override
    public boolean isEmpty() {
        return this.fileContent.length == 0;
    }
    
    @Override
    public long getSize() {
        return this.fileContent.length;
    }
    
    @Override
    public byte[] getBytes() throws IOException {
        return this.fileContent;
    }
    
    @Override
    public InputStream getInputStream() throws IOException {
        return new ByteArrayInputStream(this.fileContent);
    }
    
    @Override
    public void transferTo(File dest) throws IOException, IllegalStateException {
        try (FileOutputStream fos = new FileOutputStream(dest)) {
            fos.write(this.fileContent);
        }
    }
}

// 使用自定義實(shí)現(xiàn)
public class CustomMultipartFileConverter {
    public static MultipartFile convertUsingCustom(byte[] fileBytes, String fileName) {
        return new CustomMultipartFile(fileBytes, fileName, "application/octet-stream");
    }
}

import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;

public class FileUploadService {
    
    public void uploadFile(byte[] fileBytes, String fileName) {
        // 1. 轉(zhuǎn)換為 MultipartFile
        MultipartFile multipartFile = MultipartFileUtils.convertBytesToMultipartFile(
            fileBytes, fileName, "image/jpeg");
        
        // 2. 準(zhǔn)備上傳請(qǐng)求
        MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
        body.add("file", multipartFile.getResource()); // 注意獲取Resource的方法可能因?qū)崿F(xiàn)而異
        
        // 3. 設(shè)置請(qǐng)求頭
        // HttpHeaders headers = new HttpHeaders();
        // headers.setContentType(MediaType.MULTIPART_FORM_DATA);
        
        // 4. 使用 RestTemplate 發(fā)送請(qǐng)求
        // RestTemplate restTemplate = new RestTemplate();
        // ResponseEntity<String> response = restTemplate.postForEntity(uploadUrl, request, String.class);
    }
}