How to convert byte array to MultipartFile

Question

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

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

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

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

Answer 1

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

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

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:

/* *<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);         }     } 

Answer 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.

Approach 1:

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

Approach 1: 

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

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:

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

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.

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

java.io.tmpdir with the name intermediate.pdf

Thanks.