Java BufferedImage is converted to MultipartFile mode

Error background of MultipartFile to File in directory BufferedImage conversion to MultipartFile method 1 method 2 Java data transfer found the following two methods through search engine

BufferedImage to MultipartFile

In Java, reading pictures or resizing pictures can be operated by BufferedImage (refer to my other article Java to modify picture size), but sometimes we need to change BufferedImage to MultipartFile for other operations, which can be converted as follows:

Method 1

1. Create a new ConvertToMultipartFile class to implement MultipartFile interface

import org.springframework.web.multipart.MultipartFile;
import java.io.*;
public class ConvertToMultipartFile implements MultipartFile {
    private byte[] fileBytes;
    String name;
    String originalFilename;
    String contentType;
    boolean isEmpty;
    long size;
    public ConvertToMultipartFile(byte[] fileBytes, String name, String originalFilename, String contentType,
                          long size) {
        this.fileBytes = fileBytes;
        this.name = name;
        this.originalFilename = originalFilename;
        this.contentType = contentType;
        this.size = size;
        this.isEmpty = false;
    }
    @Override
    public String getName() {
        return name;
    }
    @Override
    public String getOriginalFilename() {
        return originalFilename;
    }
    @Override
    public String getContentType() {
        return contentType;
    }
    @Override
    public boolean isEmpty() {
        return isEmpty;
    }
    @Override
    public long getSize() {
        return size;
    }
    @Override
    public byte[] getBytes() throws IOException {
        return fileBytes;
    }
    @Override
    public InputStream getInputStream() throws IOException {
        return new ByteArrayInputStream(fileBytes);
    }
    @Override
    public void transferTo(File dest) throws IOException, IllegalStateException {
        new FileOutputStream(dest).write(fileBytes);
    }
}

2. Conversion of BufferedImage to MultipartFile

BufferedImage is first converted to byte [], and then converted to MultipartFile through the above ConvertToMultipartFile class

 try {
            // Read the picture and convert it to  BufferedImage
            BufferedImage image = ImageIO.read(new FileInputStream("F:/test/pic1.jpg"));
            //BufferedImage  Convert to  ByteArrayOutputStream
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            ImageIO.write(image, "jpg", out);
            //ByteArrayOutputStream  Convert to  byte[]
            byte[] imageByte = out.toByteArray();
            // Will  byte[]  Convert to  MultipartFile
            MultipartFile multipartFile = new ConvertToMultipartFile(imageByte, "newNamepic", "pic1", "jpg", imageByte.length);
      } catch (IOException e) {
            e.printStackTrace();
      }

Method 2

Introducing dependencies:

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>5.3.2</version>
        <scope>compile</scope>
    </dependency>

 try {
    // Read the picture and convert it to  BufferedImage
            BufferedImage image = ImageIO.read(new FileInputStream("F:/test/pic1.jpg"));
            // After resizing the picture BufferedImage . resizeImage The method is to resize the picture can refer to the beginning of the article on me 1 Article 
            BufferedImage newImage = ImageUtils.resizeImage(image, 200, 200);
            // Will newImage Write byte array output stream 
   ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ImageIO.write( newImage, "jpg", baos );
            
   // Convert to MultipartFile 
            MultipartFile multipartFile = new MockMultipartFile("pic1.jpg", baos.toByteArray());
       } catch (IOException e) {
            e.printStackTrace();
       }

Transfer from MultipartFile to File in Java data transfer

Error background

Since the file is stored on the third party server, all the need is to convert the received MultipartFile file to File and then transfer it. (Spring MVC)

The following two methods were found through the search engine

Are stated in spring xml. As follows:

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />  

If you need to add maximum and minimum range controls, please refer to Baidu by yourself.

Method 1: Turn strongly

Method 2:

CommonsMultipartFile cf = (CommonsMultipartFile)multfile;  
DiskFileItem fi = (DiskFileItem) cf.getFileItem(); 
File file = fi.getStoreLocation();

Pro-test is effective. However, it is found that the setting problem in the later period leads to errors in file conversion, and the file is unreadable, which leads to the program throwing is not a normal file exception.

Because of the randomness of error occurrences, we chose to use buffers to implement this transformation-using the MultipartFile. transferto () method for temporary files created by java.

The code is as follows:

File f = null;
try {
    f=File.createTempFile("tmp", null);
    file.transferTo(f);<br> 　　  f.deleteOnExit();        
} catch (HttpException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}

Pro-test is effective.