Reconvert a base64 String to save an image into local storage

Question

I want to reconvert a base64 cripted image, to stored this image in the server. For example I have uploaded an image from angular, my base64 encoder generates this json file:

{
"filetype": "image/png",
"filename": "StudyPlan.png",
"filesize": 88008,
"base64": "iVBORw0KGgoAAAANSUhEUgAAA3oAAALBCAIAAACBS0QtAAAAAX…hRIxIbgohhBBCiNi4e/f/A/9ytmLOCOL/AAAAAElFTkSuQmCC"
}

I want to reconvert the base64 String attribute to save the image in local storage. For this reason I have implemented a java class:

@Path("/upload")
public class UploadImageServices {
 @POST
 @Produces(MediaType.APPLICATION_JSON)
 public int addImage(MyFile file) throws IOException  {
 
  String imageString = file.getBase64();

  // create a buffered image
  BufferedImage image = null;
  byte[] imageByte;

  BASE64Decoder decoder = new BASE64Decoder();
  imageByte = decoder.decodeBuffer(imageString);
  ByteArrayInputStream bis = new ByteArrayInputStream(imageByte);
  image = ImageIO.read(bis);
  bis.close();

  // write the image to a file
  File outputfile = new File("image.png");
  ImageIO.write(image, "png", outputfile);
  return 0;
 }
}

Where MyFile a model from MyFile.java:

package it.jack.fdd.util;

public class MyFile {
 private String filetype;
 private String filename;
 private Integer filesize;
 public String getFiletype() {
  return filetype;
 }
 public void setFiletype(String filetype) {
  this.filetype = filetype;
 }
 public String getFilename() {
  return filename;
 }
 public void setFilename(String filename) {
  this.filename = filename;
 }
 public Integer getFilesize() {
  return filesize;
 }
 public void setFilesize(Integer filesize) {
  this.filesize = filesize;
 }
 public String getBase64() {
  return base64;
 }
 public void setBase64(String base64) {
  this.base64 = base64;
 }
 private String base64;
}

When I send that Json String, give me error 500:

and I don't explain why it doesn't works. What is the error in my java class? It really can save an image?

new error with the real json string:

java.lang.NullPointerException
 javax.imageio.ImageIO.write(ImageIO.java:1538)
 it.jack.fdd.services.UploadImageServices.addImage(UploadImageServices.java:55)
 sun.reflect.GeneratedMethodAccessor62.invoke(Unknown Source)
 sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 java.lang.reflect.Method.invoke(Method.java:497)
 com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
 com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185)
 com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
 com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302)
 com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
 com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
 com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
 com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542)
 com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473)
 com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419)
 com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409)
 com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409)
 com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:558)
 com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:733)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
 org.apache.catalina.filters.CorsFilter.handleSimpleCORS(CorsFilter.java:301)
 org.apache.catalina.filters.CorsFilter.doFilter(CorsFilter.java:169)

Are you sure your `base64` payload is a `png` image? It looks clipped. — Elliott Frisch, Dec 31 '16 at 02:57
Yes, it is a png image! Look my json string: it is create automatically — Giacomo Brunetta, Dec 31 '16 at 03:03
I did look. It shows the size is `88008`; the posted `base64` string is clearly not 80k. I'm asking if you've verified that the automatically created payload string is decodable. The error you've posted, though hard to read (please post text), indicates the `byte[]` received isn't a png image (because it's trying to skip some kind of metadata that isn't there). — Elliott Frisch, Dec 31 '16 at 03:05
Not really. And even if I could, that's not how you verify the payload. Save the JSON to a file. Use a Base64 decoder (google one) to decode it to a png, open the png. Once you see your image, you've verified it. — Elliott Frisch, Dec 31 '16 at 03:08
Ok. I have tried with a utility that convert in base64, and you're right!!! Do you know a simply js script that can codify fully an Image into a base64 String? — Giacomo Brunetta, Dec 31 '16 at 03:16
[Here](http://stackoverflow.com/questions/36280818/how-to-convert-file-to-base64-in-javascript) you go. — Elliott Frisch, Dec 31 '16 at 03:20
I'm sorry!! I wrong to copy the string to actually generates good !!!! In fact, taking it right by me still another error, look here, I'm editing — Giacomo Brunetta, Dec 31 '16 at 03:21
Ah no, sorry..it is truncated. I have too much sleep now, It's 4:26 AM! I must go to sleep now, I try again tomorrow. If you will help me, I'd be happy. Thanks anyway. — Giacomo Brunetta, Dec 31 '16 at 03:27

Reconvert a base64 String to save an image into local storage

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