Monday 10 June 2024

Handling Multiple File Uploads with Same Name in Javalin

Using context.uploadedFiles("name") method, we can read all the uploaded files by given name.

Example

List<UploadedFile> uploadedFiles = ctx.uploadedFiles("myFile");

 

Find the below working application.

 

Step 1: Create new maven project ‘javalin-read-uploaded-files-by-given-name’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.sample.app</groupId>
    <artifactId>javalin-read-uploaded-files-by-given-name</artifactId>
    <version>1.0.0</version>

    <properties>
        <packaging>jar</packaging>
        <jdk.version>17</jdk.version>
        <release.version>17</release.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>io.javalin</groupId>
            <artifactId>javalin</artifactId>
            <version>5.3.2</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>2.0.3</version>
        </dependency>


        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.14.0</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.14.0</version>
        </dependency>


    </dependencies>

    <build>
        <plugins>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.10.1</version>
                <configuration>
                    <source>17</source>
                    <target>17</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <mainClass>com.sample.app.App</mainClass>
                        </manifest>
                    </archive>
                </configuration>
                <executions>
                    <execution>
                        <id>assemble-all</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Step 3: Define JsonUtil class.

 

JsonUtil.java

package com.sample.app.util;

import java.io.IOException;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonUtil {
    public static String marshal(Object obj) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(obj);
    }

    public static <T> T unmarshal(Class<T> clazz, String json)
            throws JsonParseException, JsonMappingException, IOException {
        ObjectMapper mapper = new ObjectMapper();
        return (T) mapper.readValue(json, clazz);
    }
}

Step 4: Define FileUploadResponseDto class.

 

FileUploadResponseDto.java

package com.sample.app.dto;

public class FileUploadResponseDto {

    private String contentType;
    private String content;
    private long fileSizeInBytes;
    private String fileName;

    public String getContentType() {
        return contentType;
    }

    public void setContentType(String contentType) {
        this.contentType = contentType;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public long getFileSizeInBytes() {
        return fileSizeInBytes;
    }

    public void setFileSizeInBytes(long fileSizeInBytes) {
        this.fileSizeInBytes = fileSizeInBytes;
    }

    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

}

Step 5: Define main application class.

 

App.java

package com.sample.app;

import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

import com.sample.app.dto.FileUploadResponseDto;
import com.sample.app.util.JsonUtil;

import io.javalin.Javalin;
import io.javalin.http.HttpStatus;
import io.javalin.http.UploadedFile;

public class App {

    public static void main(String[] args) {

        Javalin javalin = Javalin.create();

        javalin.get("/", (ctx) -> {
            ctx.result("Welcome to Javalin programming!!!!");
        });

        javalin.post("/echo-files-content", (ctx) -> {

            List<UploadedFile> uploadedFiles = ctx.uploadedFiles("myFile");
            List<FileUploadResponseDto> responseList = new ArrayList<>();

            for (UploadedFile uploadedFile : uploadedFiles) {
                String contentType = uploadedFile.contentType();
                InputStream inputStream = uploadedFile.content();
                String fileContent = new String(inputStream.readAllBytes(), StandardCharsets.UTF_8);
                long fileSizeInBytes = uploadedFile.size();
                String fileName = uploadedFile.filename();

                FileUploadResponseDto fileUploadesponseDto = new FileUploadResponseDto();
                fileUploadesponseDto.setContent(fileContent);
                fileUploadesponseDto.setContentType(contentType);
                fileUploadesponseDto.setFileName(fileName);
                fileUploadesponseDto.setFileSizeInBytes(fileSizeInBytes);

                responseList.add(fileUploadesponseDto);
            }

            ctx.result(JsonUtil.marshal(responseList)).status(HttpStatus.CREATED);
        });

        javalin.start(8080);
    }

}

Total project structure looks like below.


 

Build the project

Navigate to the folder, where pom.xml is located and execute the command ‘mvn package’.

 

Upon successful command execution, you can see a ‘javalin-read-uploaded-files-by-given-name-1.0.0-jar-with-dependencies.jar’ file.

$ls ./target 
archive-tmp
classes
generated-sources
generated-test-sources
javalin-read-uploaded-files-by-given-name-1.0.0-jar-with-dependencies.jar
javalin-read-uploaded-files-by-given-name-1.0.0.jar
maven-archiver
maven-status
test-classes

Run the application

Execute below command to run the application

java -jar ./target/javalin-read-uploaded-files-by-given-name-1.0.0-jar-with-dependencies.jar

$java -jar ./target/javalin-read-uploaded-files-by-given-name-1.0.0-jar-with-dependencies.jar
[main] INFO io.javalin.Javalin - Starting Javalin ...
[main] INFO org.eclipse.jetty.server.Server - jetty-11.0.13; built: 2022-12-07T20:47:15.149Z; git: a04bd1ccf844cf9bebc12129335d7493111cbff6; jvm 17.0.5+9-LTS-191
[main] INFO org.eclipse.jetty.server.session.DefaultSessionIdManager - Session workerName=node0
[main] INFO org.eclipse.jetty.server.handler.ContextHandler - Started i.j.j.@30ee2816{/,null,AVAILABLE}
[main] INFO org.eclipse.jetty.server.AbstractConnector - Started ServerConnector@26a7b76d{HTTP/1.1, (http/1.1)}{0.0.0.0:8080}
[main] INFO org.eclipse.jetty.server.Server - Started Server@1fc2b765{STARTING}[11.0.13,sto=0] @481ms
[main] INFO io.javalin.Javalin - 
       __                  ___          ______
      / /___ __   ______ _/ (_)___     / ____/
 __  / / __ `/ | / / __ `/ / / __ \   /___ \
/ /_/ / /_/ /| |/ / /_/ / / / / / /  ____/ /
\____/\__,_/ |___/\__,_/_/_/_/ /_/  /_____/

       https://javalin.io/documentation

[main] INFO io.javalin.Javalin - Listening on http://localhost:8080/
[main] INFO io.javalin.Javalin - You are running Javalin 5.3.2 (released January 22, 2023).
[main] INFO io.javalin.Javalin - Javalin started in 324ms \o/

Test the API

 

demo1.txt

Hello world
Hi there!!!!

demo2.txt

one
two
three

Execute below command to run the application.

curl --location --request POST 'http://localhost:8080/echo-files-content' \
--form 'myFile=@"/Users/krishna/Desktop/demo1.txt"' \
--form 'myFile=@"/Users/krishna/Desktop/demo2.txt"'

$curl --location --request POST 'http://localhost:8080/echo-files-content' \
> --form 'myFile=@"/Users/krishna/Desktop/demo1.txt"' \
> --form 'myFile=@"/Users/krishna/Desktop/demo2.txt"'
[{"contentType":"text/plain","content":"Hello world\nHi there!!!!","fileSizeInBytes":24,"fileName":"demo1.txt"},{"contentType":"text/plain","content":"one\ntwo\nthree\n","fileSizeInBytes":14,"fileName":"demo2.txt"}]

You can download this application from this link.


  

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