I am trying to display an image in a Thymeleaf template that is coming from a MySql Database.
Most of it is working but I have a problem with the controller code :
#GetMapping(value = "/image/{someId}", produces = {MediaType.IMAGE_JPEG_VALUE, MediaType.IMAGE_PNG_VALUE})
public ResponseEntity<byte[]> getPicture(#PathVariable("someId") long someId) throws IOException {
byte[] imageContent = //Getting the blob element from the Repo through a service
final HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.IMAGE_JPEG);
headers.set("Content-Disposition", "attachment; filename=fileName.jpg");
headers.setContentLength(imageContent.length);
return new ResponseEntity<byte[]>(imageContent, headers, HttpStatus.OK);
}
My code is similar to solutions that ware suggested here (see this answer or this one) but my template won't display the image as its content is most probably not valid. If I reach the endpoint directly from the browser, a "filename.jpg" image will download (makes sense following the code above) but that only contains the original name of the image if I open it with a text editor. It's not an image.
There's surely something that I am missing in the configuration of the ResponseEntity. Do you perhaps have some documentation I could read about the process because I don't understand fully what is going on.
Related
#Controller
#Slf4j
public class SeckillGoodsController {
#Autowired
RedisTemplate redisTemplate;
#GetMapping("/captcha")
public void verifyCode(Long userId,Long goodsId, HttpServletResponse response){
//set Header as pic
response.setContentType("image/gif");
// no cookie keep every flush is new captcha
response.setContentType("text/html;charset=UTF-8");
response.setCharacterEncoding("utf-8");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);//never expires
//Use a util [enter image description here][1]
ArithmeticCaptcha captcha = new ArithmeticCaptcha(130, 32, 3);
redisTemplate.opsForValue().set("captcha:"+userId+":"+goodsId,captcha.text(),60, TimeUnit.SECONDS);
try {
System.out.println(response.getOutputStream().toString());
captcha.out(response.getOutputStream());
} catch (IOException e) {
log.error("Errot",e.getMessage());
}
}
}
I send a response to vue.js but use postman test the Body always is captcha, I've set the UTF-8, but it's still wrong
[1]: https://i.stack.imgur.com/04RKS.png
this has nothing to do with Spring Boot.
I'm not entirely sure what the ArithmeticCaptcha does but I guess it creates an image and stream it to the response stream
I don't know what you would expect... You are sending binary data (an image) so it is quite normal that you can't read it.
You are setting the content type twice. You can't do that. In addition, it seems to be png so you might want to check it out.
I guess that you want to would like to get a JSON back or similar. In that case, you need to change your code
Here is an example:
#ResponseBody
#RequestMapping("/captcha")
public JsonResult captcha(Long userId, Long goodsId, HttpServletResponse response) throws Exception {
ArithmeticCaptcha captcha = new ArithmeticCaptcha(130, 32, 3);
String key = "captcha:"+userId+":"+goodsId
redisTemplate.opsForValue().set(key, captcha.text(), 60, TimeUnit.SECONDS);
return JsonResult.ok().put("key", key).put("image", captcha.toBase64());
}
Might need some tweaks to fit 100% your case but this will return a json with a key that is the one you probably will need to match in your next step and the image base64 encoded so it would be (almost) readable.
You can then add the base64 encoded string from the response as the src of your img tag.
I am currently testing one of my services with Spring boot test.The service exports all user data and produces a CSV or PDF after successful completion. A file is downloade in browser.
Below is the code i have wrote in my test class
MvcResult result = MockMvc.perform(post("/api/user-accounts/export").param("query","id=='123'")
.contentType(MediaType.APPLICATION_JSON_VALUE)
.accept(MediaType.APPLICATION_PDF_VALUE)
.content(TestUtil.convertObjectToJsonBytes(userObjectDTO)))
.andExpect(status().isOk())
.andExpect(content().contentType(MediaType.APPLICATION_PDF_VALUE))
.andReturn();
String content = result.getResponse().getContentAsString(); // verify the response string.
Below is my resource class code (call comes to this place)-
#PostMapping("/user-accounts/export")
#Timed
public ResponseEntity<byte[]> exportAllUsers(#RequestParam Optional<String> query, #ApiParam Pageable pageable,
#RequestBody UserObjectDTO userObjectDTO) {
HttpHeaders headers = new HttpHeaders();
.
.
.
return new ResponseEntity<>(outputContents, headers, HttpStatus.OK);
}
While I debug my service, and place debug just before the exit, I get content Type as 'application/pdf' and status as 200.I have tried to replicate the same content type in my test case. Somehow it always throws below error during execution -
java.lang.AssertionError: Status
Expected :200
Actual :406
I would like to know, how should i inspect my response (ResponseEntity). Also what should be the desired content-type for response.
You have problem some where else. It appears that an exception/error occurred as noted by application/problem+json content type. This is probably set in the exception handler. As your client is only expecting application/pdf 406 is returned.
You can add a test case to read the error details to know what exactly the error is.
Something like
MvcResult result = MockMvc.perform(post("/api/user-accounts/export").param("query","id=='123'")
.contentType(MediaType.APPLICATION_JSON_VALUE)
.accept(MediaType.APPLICATION_PROBLEM_JSON_VALUE)
.content(TestUtil.convertObjectToJsonBytes(userObjectDTO)))
.andExpect(status().isOk())
.andExpect(content().contentType(MediaType.APPLICATION_PROBLEM_JSON_VALUE))
.andReturn();
String content = result.getResponse().getContentAsString(); // This should show you what the error is and you can adjust your code accordingly.
Going forward if you are expecting the error you can change the accept type to include both pdf and problem json type.
Note - This behaviors is dependent on the spring web mvc version you have.
The latest spring mvc version takes into account the content type header set in the response entity and ignores what is provided in the accept header and parses the response to format possible. So the same test you have will not return 406 code instead would return the content with application json problem content type.
I found the answer with help of #veeram and came to understand that my configuration for MappingJackson2HttpMessageConverter were lacking as per my requirement. I override its default supported Mediatype and it resolved the issue.
Default Supported -
implication/json
application*/json
Code change done to fix this case -
#Autowired
private MappingJackson2HttpMessageConverter jacksonMessageConverter;
List<MediaType> mediaTypes = new ArrayList<>();
mediaTypes.add(MediaType.ALL);
jacksonMessageConverter.setSupportedMediaTypes(mediaTypes);
406 means your client is asking for a contentType (probably pdf) that the server doesn't think it can provide.
I'm guessing the reason your code is working when you debug is that your rest client is not adding the ACCEPT header that asks for a pdf like the test code is.
To fix the issue, add to your #PostMapping annotation produces = MediaType.APPLICATION_PDF_VALUE see https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/bind/annotation/PostMapping.html#produces--
I am building a framework for e-commerce site. I have used jersey to create REST APIs. I need to send images to the clients as per the request.
How can I do so from my application server as Tomcat and jersey as REST API?
Since I am new to this, I have no clue how to send images to an Android client when they are shown as item.
Every resource is identified by the URI, client will ask for a particular image or a bunch of images by quering the URL, So you just need to expose a service, following service is an example to send single image to client.
#GET
#Path("/images/{imageId}")
#Produces("image/png")
public Response downloadImage(#PathParam("imageId") String imageId) {
MultiMediaDB imageDb = new MultiMediaDB();
String filePath = imageDb.getImage(imageId);
File file = new File(filePath);
ResponseBuilder response = Response.ok((Object) file);
response.header("Content-Disposition",
"attachment; filename=\"fileName.png\"");
return response.build();
}
MultiMediaDB is my custom class to get the file location from the DB, you can hardcode it as of now for testing purpose like D:\server_image.png.
You need to mention Content-Disposition as an attachment so that file will not be downloaded, instead attached to the form. In android you just need to read inputstream from a HttpURLConnection object and send that to bitmap as shown below
URL url = new URL(BaseUrl + "/images/" + imageId);
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.connect();
iStream = urlConnection.getInputStream();
bitmap = BitmapFactory.decodeStream(iStream);
The you can set that bitmap to imageview or what ever you have as a container.
I have this controller methods that depending on the parameters introduced by the user downloads a certain PDF file and shows a view with its different pages converted to PNG.
So the way I approached it works like this:
First I map a method to receive the post data sent by the user, then generate the URL of the actual PDF converter and pass it to the model:
#RequestMapping(method = RequestMethod.POST)
public String formPost(Model model, HttpServletRequest request) {
//Gather parameters and generate PDF url
Long idPdf = Long.parseLong(request.getParam("idPdf"));
//feed the jsp the url of the to-be-generated image
model.addAttribute("image", "getImage?idPdf=" + idPdf);
}
Then in getImageMethod I download the PDF and then generate a PNG out of it:
#RequestMapping("/getImage")
public HttpEntity<byte[]> getPdfToImage(#RequestParam Long idPdf) {
String url = "myPDFrepository?idPDF=" + idPdf;
URL urlUrl = new URL(url);
URLConnection urlConnection;
urlConnection = urlUrl.openConnection();
InputStream is = urlConnection.getInputStream();
return PDFtoPNGConverter.convert(is);
}
My JSP just has an img tag that refers to this url:
<img src="${image}" />
So far this work perfectly. But now I need to allow the possibility of viewing multi page PDFs, converted as PNGS, each of them in a different page. So I would add a page parameter, then feed my model with the image url including that page parameter, and in my getImage method I would convert only that page.
But the way it is implemented, I would be downloading the PDF again for each page, plus an additional time for the view, so it can find out whether this specific PDF has more pages and then show the "prev" and "next" buttons.
What would be a good way to preserve the same file during these requests, so I download it just once? I thought about using temp files but then managing its deletion might be a problem. So maybe storing the PDF in the session would be a good solution? I don't even know if this is good practice or not.
I am using Spring MVC by the way.
I think the simplest way would be using spring cache abstraction. Look at tutorial and will need to change your code a little: move logic that load pdf to separate class.
it will looks like:
interface PDFRepository {
byte[] getImage(long id);
}
#Repository
public class PDFRepositoryImpl implements PDFRepository {
#Cacheable
public byte[] getImage(long id) {
String url = "myPDFrepository?idPDF=" + idPdf;
URL urlUrl = new URL(url);
URLConnection urlConnection;
urlConnection = urlUrl.openConnection();
InputStream is = urlConnection.getInputStream();
return PDFtoPNGConverter.convert(is);
}
}
You will get pluggable cache implementation support and good cache expiration management.
I use a servlet to get images that saved out of my project. Code in my servlet is:
String file = request.getParameter("file");
BufferedInputStream in = new BufferedInputStream(new FileInputStream(directory + file));
// Get image contents.
byte[] bytes = new byte[in.available()];
in.read(bytes);
in.close();
// Write image contents to response.
response.getOutputStream().write(bytes);
The HTML image tags are like this:
<img src="/images/?file=example.jpg" />
Everything is good. But now I would like to have image filename in URI instead of as request parameter like so:
<img src="/images/example.jpg" />
How can I achieve it?
Map the servlet on a prefix URL pattern /images/* instead of an apparently exact URL pattern /images. Then, you can specify URLs exactly like that and obtain the filename as URI path information by HttpServletRequest#getPathInfo().
Kickoff example:
#WebServlet("/images/*")
public class ImageServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String filename = request.getPathInfo().substring(1);
File file = new File(directory, filename);
response.setHeader("Content-Type", getServletContext().getMimeType(file.getName()));
response.setHeader("Content-Length", String.valueOf(file.length()));
Files.copy(file.toPath(), response.getOutputStream());
}
}
Unrelated to the concrete problem: InputStream#available() as in your initial code doesn't do what you apparently thought it does. It doesn't return the entire length of the content. It just returns the length of the first block which the code can read without blocking the disk file system I/O. I.e. it returns the length of content currently in I/O buffer. This does not necessarily represent the entire content length! For sure not on larger images. If you're on Java 7, just use Files#copy() if the sole purpose is to achieve the job with least possible amount of code as shown above.