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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