如何用Java和Kotlin實現高性能桌面條形碼掃描

很多做Java開發的喜歡用ZXing實現掃碼功能，但是ZXing的功能有限。如果要開發企業級的產品，就需要企業級的SDK。Dynamsoft Barcode Reader作爲企業級的掃碼SDK，提供了移動和桌面版本。SDK基於JNI封裝，能夠給Java程序提供最好的性能。

使用Gradle創建Java/Kotlin工程

習慣安卓開發的都很熟悉Gradle。Gradle用於桌面程序開發也很方便。

用Gradle命令創建一個新的工程：

$ 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] 

創建的時候，編程語言可以選擇Java或者Kotlin。

打開 app > build.gradle。加入Maven倉庫和依賴：

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:8.1.2'
 }

如果要做Android開發，URL和依賴的名字需要修改下：

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

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

Java/Kotlin桌面掃碼程序

打開App.java/App.kt文件，創建BarcodeReader對象：

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

BarcodeReader br = new BarcodeReader(license);

// Kotlin
import com.dynamsoft.dbr.*

val br = BarcodeReader(license)

設置初始化參數：

// 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)

讀取文件解碼，返回結果：

// 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
        )
    )
}

現在測試一張模糊的QR二維碼：

在Gradle運行命令中加上文件名和license文件：

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

如果沒有license，程序也可以運行，但是結果會被混淆。可以申請一個免費的30天試用license來顯示正確的結果。

使用Travis CI測試Windows, Linux和Mac

如果想測試下這個命令行掃碼程序是否可以在Windows, Linux和Mac上正常運行，可以配置.travis.yml文件：

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"

Travis CI的Windows虛擬機目前不支持Java，可以嘗試手動安裝。在Linux和Mac上需要用chmod +x修改gradlew的權限。

源碼

https://github.com/yushulx/gradle-java-kotlin-barcode-sample