File转成MultipartFile类型

转换方式

需要加入依赖

        <!--File转MultipartFile需要test包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.3.13</version>
        </dependency>

package com.hx.utils;

import org.apache.tomcat.util.http.fileupload.FileItem;
import org.apache.tomcat.util.http.fileupload.FileItemFactory;
import org.apache.tomcat.util.http.fileupload.disk.DiskFileItemFactory;
import org.springframework.mock.web.MockMultipartFile;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.commons.CommonsMultipartFile;

import java.io.*;
import java.nio.charset.StandardCharsets;

public class FileToMultipartFileConverter {

    public static MultipartFile convert(File file) throws IOException {
        // 检查文件是否存在
        if (!file.exists() || !file.isFile()) {
            throw new IllegalArgumentException("文件不存在或不是一个文件");
        }
        // 创建一个 FileInputStream 来读取文件内容
        FileInputStream input = new FileInputStream(file);
        // 使用 Spring 的 MockMultipartFile 类来创建 MultipartFile 实例
        MultipartFile multipartFile = new MockMultipartFile("file", file.getName(), "text/plain", input);
        // 关闭 FileInputStream
        input.close();
        return multipartFile;
    }
    public static void convert2() {
// 第一种方式：根据文件名称、文件内容转换
// 其中fileName为对方收的文件名
        String fileName = "test.txt";
        String fileContent = "test content";
        MultipartFile multipartFile = new MockMultipartFile(fileName, fileContent.getBytes(StandardCharsets.UTF_8));
    }
    public static void convert1() throws IOException {

// 第二种方式：文件名称、输入流内容
// 这种方式需要文件的路径
// 其中fileName为对方收的文件名
        String fileName = "test.txt";
        String filePath = "D:/test.txt";
        MultipartFile multipartFile = new MockMultipartFile(fileName, new FileInputStream(filePath));
// 这种和上面一样
        File file = new File("filePath");
        new MockMultipartFile(fileName, new FileInputStream(file));

    }



    public static File convertMultipartFileToFile(MultipartFile multipartFile) {
        File file = new File(multipartFile.getOriginalFilename());
        try (OutputStream os = new FileOutputStream(file)) {
            InputStream is = multipartFile.getInputStream();
            byte[] buffer = new byte[1024];
            int bytesRead;
            // read from is to buffer
            while ((bytesRead = is.read(buffer)) != -1) {
                os.write(buffer, 0, bytesRead);
            }
            is.close();
            // flush OutputStream to write any buffered data to file
            os.flush();
        } catch (Exception e) {
            // Handle exception
            e.printStackTrace();
            return null;
        }
        return file;
    }
}