OCRController 2

OCRController.kt

import org.springframework.beans.factory.annotation.Autowired
import org.springframework.http.MediaType
import org.springframework.http.ResponseEntity
import org.springframework.validation.annotation.Validated
import org.springframework.web.bind.annotation.PostMapping
import org.springframework.web.bind.annotation.RequestBody
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RestController
import org.springframework.web.multipart.MultipartFile
import javax.validation.constraints.NotNull

@RestController
@RequestMapping("/api/ocr")
@Validated
class OCRController {
    @Autowired
    private lateinit var ocrService: OCRService

    @PostMapping(consumes = [MediaType.MULTIPART_FORM_DATA_VALUE])
    fun ocr(@NotNull file: MultipartFile): ResponseEntity<String> {
        val ocrOutput = ocrService.performOCR(file)
        return ResponseEntity.ok(ocrOutput)
    }
}

OCRService.kt

import com.google.cloud.vision.v1.AnnotateImageRequest
import com.google.cloud.vision.v1.Feature
import com.google.cloud.vision.v1.Image
import com.google.cloud.vision.v1.ImageAnnotatorClient
import com.google.cloud.vision.v1.ImageContext
import com.google.protobuf.ByteString
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.stereotype.Service
import org.springframework.web.multipart.MultipartFile

@Service
class OCRService {
    @Autowired
    private lateinit var imageAnnotatorClient: ImageAnnotatorClient

    fun performOCR(file: MultipartFile): String {
        val imageBytes = ByteString.copyFrom(file.bytes)
        val image = Image.newBuilder().setContent(imageBytes).build()
        val imageRequest = AnnotateImageRequest.newBuilder()
            .addFeatures(Feature.newBuilder().setType(Feature.Type.TEXT_DETECTION))
            .setImage(image)
            .setImageContext(ImageContext.newBuilder().setLanguageHints("en").build())
            .build()
        val response = imageAnnotatorClient.batchAnnotateImages(listOf(imageRequest))
        val annotation = response.responsesList[0].textAnnotationsList[0]

        return annotation.description
    }
}