How to Build Desktop Barcode Scanner in Java and Kotlin

Mar 08, 2021

Dynamsoft offers Java Barcode SDKs for both mobile and desktop development. The mobile edition is available as an Android AAR package, while the desktop edition is provided as a JAR package. This article is designed to assist developers in building desktop or server-side barcode scanner applications using Java or Kotlin.

This article is Part 3 in a 5-Part Series.

Installing Dynamsoft Barcode Reader via Gradle

To get Dynamsoft Barcode Reader, you can either download the SDK directly or configure the Maven URL for auto-build tools. Using Gradle to create a Java or Kotlin barcode scanner project is recommended.

Steps to Create a New Gradle Project

Create a new Gradle project:

 $ gradle init
 Select type of project to generate:
 1: basic
 2: application
 3: library
 4: Gradle plugin
 Enter selection (default: basic) [1..4] 

 Select implementation language:
 1: C++
 2: Groovy
 3: Java
 4: Kotlin
 5: Scala
 6: Swift
 Enter selection (default: Java) [1..6] 

 Split functionality across multiple subprojects?:
 1: no - only one application project
 2: yes - application and library projects
 Enter selection (default: no - only one application project) [1..2] 

 Select build script DSL:
 1: Groovy
 2: Kotlin
 Enter selection (default: Kotlin) [1..2] 

Add the Maven repository hosted by Dynamsoft and the dependency in app > build.gradle:

 repositories {
     // Use JCenter for resolving dependencies.
     jcenter()
     maven {
         url "http://download2.dynamsoft.com/maven/dbr/jar"
     }
 }

 dependencies {
     // Use JUnit test framework.
     testImplementation 'junit:junit:4.13'

     // This dependency is used by the application.
     implementation 'com.google.guava:guava:29.0-jre'

     // Dynamsoft Barcode Reader SDK
     implementation 'com.dynamsoft:dbr:9.6.40.1'
 }

Note: for building Android barcode scanner projects, the URL and the package name are different:

 repositories {
     maven {
         url "http://download2.dynamsoft.com/maven/dbr/aar"
     }
 }

 dependencies {
     implementation 'com.dynamsoft:dynamsoftbarcodereader:latest.release@aar'
 }

Java Barcode Scanner Application for Windows, Linux, and macOS

Dynamsoft Java Barcode SDK is implemented using Java Native Interface (JNI), offering better performance than pure Java SDKs like ZXing. Although the underlying technology is C++, the SDK wraps native libraries for multiple operating systems.

Open App.java or App.kt to instantiate the barcode reader object:

// Java
import com.dynamsoft.dbr.*;

BarcodeReader br = new BarcodeReader(license);

// Kotlin
import com.dynamsoft.dbr.*

val br = BarcodeReader(license)

Get a 30-day FREE Trial License here to unlock all API functionalities.

You can generate an appropriate template for parameter initialization using the free barcode online demo:

// Java
br.initRuntimeSettingsWithString("{\"ImageParameter\":{\"Name\":\"Balance\",\"DeblurLevel\":5,\"ExpectedBarcodesCount\":512,\"LocalizationModes\":[{\"Mode\":\"LM_CONNECTED_BLOCKS\"},{\"Mode\":\"LM_STATISTICS\"}]}}", EnumConflictMode.CM_OVERWRITE);

// Kotlin
br.initRuntimeSettingsWithString("{\"ImageParameter\":{\"Name\":\"Balance\",\"DeblurLevel\":5,\"ExpectedBarcodesCount\":512,\"LocalizationModes\":[{\"Mode\":\"LM_CONNECTED_BLOCKS\"},{\"Mode\":\"LM_STATISTICS\"}]}}", EnumConflictMode.CM_OVERWRITE)

The following sample code reads barcodes from an image file and prints out all results:

// Java
results = mBarcodeReader.decodeFile(file, "");
for (TextResult result : results) {
    System.out.println(String.format("  Barcode %d:", index++));
    if(result.barcodeFormat != 0){
        System.out.println("    Type: " + result.barcodeFormatString);
    } else {
        System.out.println("    Type: " + result.barcodeFormatString_2);
    }


    System.out.println("    Value: " + result.barcodeText);

    System.out.println(String.format("    Region points: {(%d,%d),(%d,%d),(%d,%d),(%d,%d)}",
    result.localizationResult.resultPoints[0].x, result.localizationResult.resultPoints[0].y,
    result.localizationResult.resultPoints[1].x,result.localizationResult.resultPoints[1].y,
    result.localizationResult.resultPoints[2].x,result.localizationResult.resultPoints[2].y,
    result.localizationResult.resultPoints[3].x,result.localizationResult.resultPoints[3].y));
}

// Kotlin
val results: Array<TextResult> = br.decodeFile(file, "")
for (result in results) {
    println(String.format("  Barcode %d:", index++))
    if (result.barcodeFormat != 0) {
        System.out.println("    Type: " + result.barcodeFormatString)
    } else {
        System.out.println("    Type: " + result.barcodeFormatString_2)
    }
    System.out.println("    Value: " + result.barcodeText)
    println(
        java.lang.String.format(
            "    Region points: {(%d,%d),(%d,%d),(%d,%d),(%d,%d)}",
            result.localizationResult.resultPoints.get(0).x,
            result.localizationResult.resultPoints.get(0).y,
            result.localizationResult.resultPoints.get(1).x,
            result.localizationResult.resultPoints.get(1).y,
            result.localizationResult.resultPoints.get(2).x,
            result.localizationResult.resultPoints.get(2).y,
            result.localizationResult.resultPoints.get(3).x,
            result.localizationResult.resultPoints.get(3).y
        )
    )
}

With just a few lines of code, a simple command-line barcode scanner is ready.

Here is a blurred QR code image:

blurred QR code

You can now run the Gradle command with specified arguments:

./gradlew run --args="../../images/QR-Blurred.jpg ../../license.txt"

Kotlin barcode scanner

Testing Java Applications Using Travis CI

To verify the cross-platform capability of the barcode scanner application, create a .travis.yml file for the GitHub repository:

language: java

jobs:
  include:
    - name: "Linux"
      os: linux
    - name: "macOS"
      os: osx
    - name: "Windows"
      os: windows           
      language: shell       
      before_install:
        - choco install jdk8 -params 'installdir=c:\\jdk' -y;
        - export JAVA_HOME=${JAVA_HOME:-/c/jdk};
      env: PATH=/c/jdk/bin:$PATH

branches:
  only:
    - main

script:
  - if [[ ${TRAVIS_OS_NAME} != "windows" ]]; then
        chmod +x java/gradlew;
        chmod +x kotlin/gradlew;
    fi
  - cd java
  - ./gradlew test
  - ./gradlew run --args="../../images/AllSupportedBarcodeTypes.png"
  - cd .. 
  - cd kotlin
  - ./gradlew test
  - ./gradlew run --args="../../images/AllSupportedBarcodeTypes.png"

Add chmod +x to make the gradlew script file executable on Linux and macOS.

Source Code

https://github.com/yushulx/java-jni-barcode-qrcode-reader/tree/main/examples/9.x/gradle_kotlin

LANGUAGES

PLATFORMS

FEATURED