How to display full screen animated gif for your react native app?

By Errong Leng – 26 Feb 2023 – View online →

I would like to show a fullscreen animated gif while my react native app got lunched and preparing its data. so how can we do that within react native?

import { Image } from "react-native";

A React component for displaying different types of images, including network images, static resources, temporary local images, and images from local disk, such as the camera roll.

resizeMode

Determines how to resize the image when the frame doesn't match the raw image dimensions.

'cover': Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or larger than the corresponding dimension of the view (minus padding).

'contain': Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or less than the corresponding dimension of the view (minus padding).

'stretch': Scale width and height independently, This may change the aspect ratio of the src.

'repeat': Repeat the image to cover the frame of the view. The image will keep it's size and aspect ratio. (iOS only)

'center': Scale the image down so that it is completely visible, if bigger than the area of the view. The image will not be scaled up.

useWindowDimensions

import {useWindowDimensions} from 'react-native';

useWindowDimensions automatically updates all of its values when screen size or font scale changes. You can get your application window's width and height like so:

const {height, width} = useWindowDimensions();

Final Code

```typescript
import { Image, View, useWindowDimensions } from "react-native";

const Interstitial = () => {
    const {height, width} = useWindowDimensions();
    return <View>
        <Image
        style={{
            backgroundColor: "rgb(244,5,5)",
            width,
            height
        }}
        resizeMode="contain"
        source={
            require("../../assets/image/coca-cola-share-a-coke.gif")
        }></Image>
    </View>
}

export default Interstitial;
```

References

Image · React Native

A React component for displaying different types of images, including network images, static resources, temporary local images, and images from local disk, such as the camera roll.

React Native

useWindowDimensions · React Native

useWindowDimensions automatically updates all of its values when screen size or font scale changes. You can get your application window’s width and height like so:

React Native

Reactive Mono, Flux, map, flatMap, filter, reduce and zip

Post, Code and Quiet Time.

Reactive Mono, Flux, map, flatMap, filter, reduce and zip

By Errong Leng – 25 Feb 2023 – View online →

Photo by YF Wu / Unsplash

my 2 cents understanding about Mono, Flux and its usages.

Mono is a single object publisher

Mono (reactor-core 3.5.3)

Flux is an array objects publisher

Flux (reactor-core 3.5.3)

use map to transform for any sync operations

use flatMap to transform for any async operations

use Mono.zip to aggregate multiple monos into a new Mono

Aggregate given monos into a new Mono that will be fulfilled when all of the given Monos have produced an item, aggregating their values according to the provided combinator function. An error or empty completion of any source will cause other sources to be cancelled and the resulting Mono to immediately error or complete, respectively.

Mono (reactor-core 3.5.3)

How to transform byte array to a MultipartFile resource in Java?

Post, Code and Quiet Time.

How to transform byte array to a MultipartFile resource in Java?

By Errong Leng – 25 Feb 2023 – View online →

Photo by Andrey Metelev / Unsplash

Let's assume you have a backend api and it accept MultipartFile as the request body. How can the client send a MultipartFile object in its body if client only has the bytes rather than a Resource?

implement MultipartFile interface

A representation of an uploaded file received in a multipart request.

The file contents are either stored in memory or temporarily on disk. In either case, the user is responsible for copying file contents to a session-level or persistent store as and if desired. The temporary storage will be cleared at the end of request processing.

The below sample code implement a PDF MultipartFile.

public class PdfMultipartFile implements MultipartFile {      private byte[] input;      private String name;        public PdfMultipartFile(byte[] input, String name) {          this.input = input;          this.name = name;      }        @Override      public String getName() {          return name;      }        @Override      public String getOriginalFilename() {          return name + ".pdf";      }        @Override      public String getContentType() {          return MediaType.APPLICATION_PDF_VALUE;      }        @Override      public boolean isEmpty() {          return input == null || input.length == 0;      }        @Override      public long getSize() {          return input.length;      }        @Override      public byte[] getBytes() throws IOException {          return input;      }        @Override      public InputStream getInputStream() throws IOException {          return new ByteArrayInputStream(input);      }        @Override      public void transferTo(File destination) throws IOException, IllegalStateException {          try(FileOutputStream fos = new FileOutputStream(destination)) {              fos.write(input);          }      }    }

MultipartFile.#transferTo(java.io.File)

Transfer the received file to the given destination file.

This may either move the file in the filesystem, copy the file in the filesystem, or save memory-held contents to the destination file. If the destination file already exists, it will be deleted first.

If the target file has been moved in the filesystem, this operation cannot be invoked again afterwards. Therefore, call this method just once in order to work with any storage mechanism.

NOTE: Depending on the underlying provider, temporary storage may be container-dependent, including the base directory for relative destinations specified here (e.g. with Servlet multipart handling). For absolute destinations, the target file may get renamed/moved from its temporary location or newly copied, even if a temporary copy already exists.

The good part with MultipartFile is you can verify the bytes your received or send out is the exactly file you want to transmit by transfer the bytes to a MultipartFile instance. with the help of MultipartFile::transferTo method, you can save the bytes into a file.

How to parse Multiparts response body from client side in Spring Boot?

Post, Code and Quiet Time.

How to parse Multiparts response body from client side in Spring Boot?

By Errong Leng – 25 Feb 2023 – View online →

Photo by Edgar Chaparro / Unsplash

Default HttpMessageReader for parsing "multipart/form-data" requests to a stream of Parts.

In default, non-streaming mode, this message reader stores the contents of parts smaller than maxInMemorySize in memory, and parts larger than that to a temporary file in fileStorageDirectory.

This reader can be provided to MultipartHttpMessageReader in order to aggregate all parts into a Map.

use toEntityFlux and DefaultPartHttpMessageReader for Reactive stack

Variant of toEntityFlux(Class) with a BodyExtractor.
Params:
bodyExtractor – the BodyExtractor that reads from the response
Type parameters:
– the body element type
Returns:
the ResponseEntity
Since:
5.3.2

    webclient.get()                  .uri(...uri)                  .headers(...headers)                  .retrieve()                  .toEntityFlux((inputMessage, context) -> partReader.read(ResolvableType.forType(byte[].class), inputMessage, Map.of()))                  .map(ResponseEntity::getBody)                  .flatMap(parts -> parts.reduce(MixedResponse.builder(), (body, part) -> {                      if (part.headers().getContentType().equals(MediaType.APPLICATION_JSON)) {                          val json = DataBufferUtils.join(part.content())                                  .map(buffer -> {                                      byte[] bytes = new byte[buffer.readableByteCount()];                                      buffer.read(bytes);                                      DataBufferUtils.release(buffer);                                      return jsonValueSerializer.deserializeValue(new String(bytes),                                              JSON.class);                                  });                          body.json(json);                      }                      if (part.headers().getContentType().equals(MediaType.APPLICATION_PDF)) {                          var pdf = DataBufferUtils.join(part.content())                                  .map(buffer -> buffer.asByteBuffer().array());                          body.pdf(pdf);                      }                      return body;                  })                  .map(body -> body.build()));

NOTE that the body contents must be completely consumed, relayed, or released to avoid memory leaks.

custom HttpMessageConverter for the RestTemplate

You might have to custom your own HttpMessageConverter and add into the RestTemplate message converters.

RestTemplate restTemplate = new RestTemplate();          restTemplate.getMessageConverters().add(new MultiPartMessageConverter(objectMapper));          final ResponseEntity<ResultModel> responseEntity = restTemplate.getForEntity("http://localhost:" + randomServerPort + "/test", ResultModel.class);          final ResultModel resultModel = responseEntity.getBody();          Assertions.assertNotNull(resultModel);          Assertions.assertEquals(2, resultModel.secondModel.size());          Assertions.assertEquals("Param1.Value", resultModel.firstModel.param1);          Assertions.assertEquals("Param2.Value", resultModel.firstModel.param2);

References

HttpMessageConverter (Spring Framework 6.0.5 API)

declaration: package: org.springframework.http.converter, interface: HttpMessageConverter

https://stackoverflow.com/questions/65762857/resttemplate-multipart-form-data-response

Errong Leng

How to display full screen animated gif for your react native app?

import { Image } from "react-native";

resizeMode

useWindowDimensions

Final Code

References

Reactive Mono, Flux, map, flatMap, filter, reduce and zip

Mono is a single object publisher

Flux is an array objects publisher

use map to transform for any sync operations

use flatMap to transform for any async operations

use Mono.zip to aggregate multiple monos into a new Mono

How to transform byte array to a MultipartFile resource in Java?

implement MultipartFile interface

MultipartFile.#transferTo(java.io.File)

How to parse Multiparts response body from client side in Spring Boot?

use toEntityFlux and DefaultPartHttpMessageReader for Reactive stack

custom HttpMessageConverter for the RestTemplate

References

@qzl/typed-i18n — Our Open-Source Typed i18n Project is Gaining Traction

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