后端MultipartFile接收文件转Base64

@[toc]

背景说明

最开始写的版本代码删改较多且无法运行，在其他博主给我指出问题及改进措施之后，下面的是最新汇总并测试结果有效的接口，编写日期：2022年08月12日。

下面代码是后端接收到文件，并把文件转为Base64，而不是前端传Base64传递给后端，这点需注意！
如果想前端传递Base64的需自己找文章，主要：网上的部分文章转Base64没给pom依赖，会导致找不到类，我这个是能够进行编译Base64的工具包，也注明了import的引入，记录改文章也是方便后续我自己查看而已。

测试案例+代码

测试接口1和测试接口2没太大差别，一个用了buffer缓存一个没用到而已，最终结果打印一致。

pom依赖

 <dependency>
     <groupId>commons-codec</groupId>
     <artifactId>commons-codec</artifactId>
     <version>1.10</version>
</dependency>

测试方法1

测试方法1

import com.example.demo.bean.OperateTeacherReq;
import com.example.demo.bean.TeacherReq;
import com.example.demo.config.LogAnnotation;
import com.example.demo.mapper.TeacherMapper;
import com.example.demo.response.Response;
import org.apache.commons.codec.binary.Base64;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
@RestController
public class Controller {
    //测试方法1
    @RequestMapping(value = "uploadLogo")
    public void uploadLogo(@RequestParam("file") MultipartFile fileImage) {
        String base64EncoderImg = "";
        try {
            base64EncoderImg = Base64.encodeBase64String(fileImage.getBytes());
            base64EncoderImg = "data:image/png;base64," + base64EncoderImg;
            System.out.println(base64EncoderImg);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
 }    

用postman或者apipost模拟发送接口测试结果，随便上传一个excel文件

测试方法2

测试方法2

import com.example.demo.bean.OperateTeacherReq;
import com.example.demo.bean.TeacherReq;
import com.example.demo.config.LogAnnotation;
import com.example.demo.mapper.TeacherMapper;
import com.example.demo.response.Response;
import org.apache.commons.codec.binary.Base64;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
@RestController
public class Controller {
    //测试方法2
    @RequestMapping(value = "uploadLogo2")
    public void uploadLogo2(@RequestParam("file") MultipartFile fileImage) {
        String base64EncoderImg = "";
        byte[] buffer = null;
        try {
            InputStream inputStream = fileImage.getInputStream();
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            byte[] b = new byte[1024];
            int n;
            while ((n = inputStream.read(b)) != -1)
            {
                bos.write(b, 0, n);
            }
            inputStream.close();
            bos.close();
            buffer = bos.toByteArray();
            base64EncoderImg = Base64.encodeBase64String(buffer);
            base64EncoderImg = "data:image/png;base64," + base64EncoderImg;
            System.out.println(base64EncoderImg);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

用postman或者apipost模拟发送接口测试结果，随便上传一个excel文件

打印2个测试接口输出结果相同：
代码输出格式为："data:image/png;base64," + base64EncoderImg;，结果和代码一致，确认有效
data:image/png;base64,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重要信息

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大会介绍

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