spring-boot-webflux-download-file

spring-boot-webflux-download-file

ตัวอย่างการเขียน Spring-boot WebFlux Download File

1. เพิ่ม Dependencies

pom.xml

...
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.5.RELEASE</version>
</parent>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
    </dependency>
    
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <scope>provided</scope>
    </dependency>
</dependencies>

...

หมายเหตุ lombox เป็น annotation code generator ตัวนึงครับ

2. เขียน Main Class

@SpringBootApplication
@ComponentScan(basePackages = {"com.pamarin"}) 
public class AppStarter {

    public static void main(String[] args) {
        SpringApplication.run(AppStarter.class, args);
    }

}

3. เขียน Controller

@Slf4j
@Controller
public class ResourceController {

    @GetMapping({"", "/", "/classpath"})
    public Mono<ResponseEntity<Resource>> showClassPathImage() {
        return Mono.just(
                ResponseEntity.ok()
                        .header(HttpHeaders.CONTENT_DISPOSITION, "inline; filename=\"reactive_spring.png\"")
                        .header(HttpHeaders.CONTENT_TYPE, MediaType.IMAGE_PNG_VALUE)
                        .body(new ClassPathResource("static/image/reactive_spring.png"))
        );
    }

    @GetMapping({"/classpath/download"})
    public Mono<ResponseEntity<Resource>> downloadClassPathImage() {
        return Mono.just(
                ResponseEntity.ok()
                        .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"reactive_spring.png\"")
                        .header(HttpHeaders.CONTENT_TYPE, MediaType.IMAGE_PNG_VALUE)
                        .body(new ClassPathResource("static/image/reactive_spring.png"))
        );
    }

    @GetMapping("/inputstream")
    public Mono<ResponseEntity<? extends Resource>> showInputStreamImage() {
        String fileName = "reactive_spring.png";
        return readStream(fileName)
                .map(stream -> {
                    return ResponseEntity.ok()
                            .header(HttpHeaders.CONTENT_DISPOSITION, "inline; filename=\"" + fileName + "\"")
                            .header(HttpHeaders.CONTENT_TYPE, MediaType.IMAGE_PNG_VALUE)
                            .body(new InputStreamResource(stream));
                });
    }

    @GetMapping("/inputstream/download")
    public Mono<ResponseEntity<Resource>> downloadInputStreamImage() {
        String fileName = "reactive_spring.png";
        return readStream(fileName)
                .map(stream -> {
                    return ResponseEntity.ok()
                            .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + fileName + "\"")
                            .header(HttpHeaders.CONTENT_TYPE, MediaType.IMAGE_PNG_VALUE)
                            .body(new InputStreamResource(stream));
                });
    }

    private Mono<InputStream> readStream(final String fileName) {
        return Mono
                .create((MonoSink<InputStream> callback) -> {
                    try {
                        callback.success(getClass().getResourceAsStream("/static/image/" + fileName));
                    } catch (Exception ex) {
                        log.warn("read stream error => ", ex);
                        callback.error(ex);
                    }
                })
                .doAfterSuccessOrError((InputStream stream, Throwable e) -> {
                    if (stream != null) {
                        try {
                            stream.close();
                            log.debug("Stream closed");
                        } catch (IOException ex) {
                            log.error("Can not close inputStream", ex);
                        }
                    }
                })
                .switchIfEmpty(Mono.error(new NotFoundException(fileName + " not found")));
    }
}

4. Build

cd ไปที่ root ของ project จากนั้น

$ mvn clean install

5. Run

$ mvn spring-boot:run

6. เข้าใช้งาน

เปิด browser แล้วเข้า http://localhost:8080