如何将字节数组转换为MultipartFile ?

I am receiving image in the form of BASE64 encoded String(encodedBytes) and use following approach to decode into byte[] at server side.

我正在以BASE64编码字符串(encodedBytes)的形式接收图像，并使用以下方法在服务器端解码为byte[]。

BASE64Decoder decoder = new BASE64Decoder();
byte[] decodedBytes = decoder.decodeBuffer(encodedBytes);

Now i want to convert it into MultipartFile using this byte obtained above?

现在我想用上面得到的这个字节把它转换成MultipartFile ?

Is there any way to convert byte[] to org.springframework.web.multipart.MultipartFile??

是否有办法将byte[]转换为org.springframe .web.multipart. multipartfile ?

2 个解决方案

#1

org.springframework.web.multipart.MultipartFile is an interface so firstly you are going to need to work with an implementation of this interface.

org.springframework.web.multipart。MultipartFile是一个接口，所以首先需要使用这个接口的实现。

The only implementation that I can see for that interface that you can use out-of-the-box is org.springframework.web.multipart.commons.CommonsMultipartFile. The API for that implementation can be found here

我能看到的唯一的实现是org.springframe .web.multipart.common . commonsmultipartfile。该实现的API可以在这里找到

Alternatively as org.springframework.web.multipart.MultipartFile is an interface, you could provide your own implementation and simply wrap your byte array. As a trivial example:

另外org.springframework.web.multipart。MultipartFile是一个接口，您可以提供自己的实现，并简单地封装您的字节数组。作为一个简单的例子:

/*
*<p>
* Trivial implementation of the {@link MultipartFile} interface to wrap a byte[] decoded
* from a BASE64 encoded String
*</p>
*/
public class BASE64DecodedMultipartFile implements MultipartFile
{
        private final byte[] imgContent;

        public BASE64DecodedMultipartFile(byte[] imgContent)
        {
           this.imgContent = imgContent;
            }

        @Override
            public String getName()
        {
               // TODO - implementation depends on your requirements 
                   return null;
        }

        @Override
            public String getOriginalFilename()
        {
            // TODO - implementation depends on your requirements
                return null;
        }

        @Override
        public String getContentType()
        {
            // TODO - implementation depends on your requirements
            return null;
        }

        @Override
        public boolean isEmpty()
        {
            return imgContent == null || imgContent.length == 0;
        }

        @Override
        public long getSize()
        {
            return imgContent.length;
        }

        @Override
        public byte[] getBytes() throws IOException
        {
            return imgContent;
        }

        @Override
        public InputStream getInputStream() throws IOException
        {
            return new ByteArrayInputStream(imgContent);
        }

        @Override
        public void transferTo(File dest) throws IOException, IllegalStateException
        { 
            new FileOutputStream(dest).write(imgContent);
        }
    }

#2

This answer has already been answered above. Recently i was working on the requirement to convert byte array object to multipartfile object. There are two ways to achieve this.

这个答案已经在上面回答过了。最近，我正在研究将字节数组对象转换为multipartfile对象的需求。有两种实现方法。

Approach 1:

方法1:

Use the default CommonsMultipartFile where you to use the FileDiskItem object to create it. Example:

使用默认的CommonsMultipartFile，使用FileDiskItem对象创建它。例子:

Approach 1:

Use the default CommonsMultipartFile where you to use the FileDiskItem object to create it. Example:

使用默认的CommonsMultipartFile，使用FileDiskItem对象创建它。例子:

FileItem fileItem = new DiskFileItem("fileData", "application/pdf",true, outputFile.getName(), 100000000, new java.io.File(System.getProperty("java.io.tmpdir")));              
MultipartFile multipartFile = new CommonsMultipartFile(fileItem);

Approach 2:

方法2:

Create your own custom multipart file object and convert the byte array to multipartfile.

创建您自己的自定义多部分文件对象，并将字节数组转换为多部分文件。

public class CustomMultipartFile implements MultipartFile {

private final byte[] fileContent;

private String fileName;

private String contentType;

private File file;

private String destPath = System.getProperty("java.io.tmpdir");

private FileOutputStream fileOutputStream;

public CustomMultipartFile(byte[] fileData, String name) {
    this.fileContent = fileData;
    this.fileName = name;
    file = new File(destPath + fileName);

}

@Override
public void transferTo(File dest) throws IOException, IllegalStateException {
    fileOutputStream = new FileOutputStream(dest);
    fileOutputStream.write(fileContent);
}

public void clearOutStreams() throws IOException {
if (null != fileOutputStream) {
        fileOutputStream.flush();
        fileOutputStream.close();
        file.deleteOnExit();
    }
}

@Override
public byte[] getBytes() throws IOException {
    return fileContent;
}

@Override
public InputStream getInputStream() throws IOException {
    return new ByteArrayInputStream(fileContent);
}
}

This how you can use above CustomMultipartFile object.

这就是如何使用上面的CustomMultipartFile对象。

String fileName = "intermediate.pdf";
CustomMultipartFile customMultipartFile = new CustomMultipartFile(bytea, fileName);
try {
customMultipartFile.transferTo(customMultipartFile.getFile());

} catch (IllegalStateException e) {
    log.info("IllegalStateException : " + e);
} catch (IOException e) {
    log.info("IOException : " + e);
}

This will create the required PDF and store that into

这将创建所需的PDF并将其存储到

java.io.tmpdir with the name intermediate.pdf

. io .名称为medium .pdf的tmpdir

Thanks.

谢谢。