How to Make Java Barcode Reader with Dynamsoft Barcode SDK

Last week, Dynamsoft released Barcode Reader (DBR) SDK v2.0, which is available for Windows and Mac. The Windows installer contains Barcode libraries for ActiveX, C/C++, and .NET. If you are a Java developer, you have to use JNI to link native C/C++ libraries. In this tutorial, I’ll demonstrate how to invoke the native methods of Dynamsoft Barcode SDK via JNI to create a Java Barcode Reader.

Dynamsoft Barcode Reader SDK
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JNI for Linking Dynamsoft Barcode Reader DLL

Download and install Dynamsoft Barcode Reader.DBR download button

dbr folder

Create a new Java project in Eclipse. We need a Class for calling native methods.

package com.dynamsoft.barcode;

import java.util.Properties;

public class JBarcode {

	static {

		try {
			// get arch
			Properties props = System.getProperties();
			String bits = String.valueOf(props.get("sun.arch.data.model"));
			if (bits.equals("32")) {
				bits = "86";
			}

			String jniLib = "DynamsoftBarcodeJNIx" + bits;

			// load dll
			System.loadLibrary(jniLib);
		} catch (Exception e) {
			System.err.println("load jni error!");
		}

}

    public native static int DBR_InitLicense(
		String pLicense	//License Key
	);

    public native static int DBR_DecodeFile(
		String pFileName,

		int option_iMaxBarcodesNumPerPage,
		long option_lBarcodeFormat,

		tagBarcodeResultArray ppResults	//Barcode Results
	);	

    public native static int DBR_DecodeFileRect(
		String pFileName,

		int option_iMaxBarcodesNumPerPage,
		long option_lBarcodeFormat,

		int iRectLeft,			//Rectangle Left
		int iRectTop,			//Rectangle Top
		int iRectWidth,			//Rectangle 
		int iRectHeight,		//Rectangle 
		tagBarcodeResultArray ppResults	// Barcode Results
	);

    public native static int DBR_DecodeBuffer(
		byte[] pDIBBuffer,	//Buffer
        int iDIBSize,

		int option_iMaxBarcodesNumPerPage,
		long option_lBarcodeFormat,

        tagBarcodeResultArray ppResults	//Barcode Results
	);

    public native static int DBR_DecodeBufferRect(
		byte[] pDIBBuffer,	//Buffer
        int iDIBSize,	

		int option_iMaxBarcodesNumPerPage,
		long option_lBarcodeFormat,

        int iRectLeft,			//Rectangle Left
        int iRectTop,			//Rectangle Top
        int iRectWidth,			//Rectangle 
        int iRectHeight,		//Rectangle 
        tagBarcodeResultArray ppResults	//Barcode Results
	);

    public native String GetErrorString(int iErrorCode);

}

Create a new DLL project in Visual Studio, and then add Include directories of JDK and DBR.

dbr include

Add Library directories of DBR.

dbr lib

Declare JNI methods in a header file.

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_dynamsoft_barcode_JBarcode */

#ifndef _Included_com_dynamsoft_barcode_JBarcode
#define _Included_com_dynamsoft_barcode_JBarcode

extern "C" {
/*
 * Class:     com_dynamsoft_barcode_JBarcode
 * Method:    DBR_InitLicense
 * Signature: (Ljava/lang/String;)I
 */
JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1InitLicense
  (JNIEnv *, jclass, jstring);

/*
 * Class:     com_dynamsoft_barcode_JBarcode
 * Method:    DBR_DecodeFile
 * Signature: (Ljava/lang/String;IJLcom/dynamsoft/barcode/tagBarcodeResultArray;)I
 */
JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1DecodeFile
  (JNIEnv *, jclass, jstring, jint, jlong, jobject);

/*
 * Class:     com_dynamsoft_barcode_JBarcode
 * Method:    DBR_DecodeFileRect
 * Signature: (Ljava/lang/String;IJIIIILcom/dynamsoft/barcode/tagBarcodeResultArray;)I
 */
JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1DecodeFileRect
  (JNIEnv *, jclass, jstring, jint, jlong, jint, jint, jint, jint, jobject);

/*
 * Class:     com_dynamsoft_barcode_JBarcode
 * Method:    DBR_DecodeBuffer
 * Signature: ([BIIJLcom/dynamsoft/barcode/tagBarcodeResultArray;)I
 */
JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1DecodeBuffer
  (JNIEnv *, jclass, jbyteArray, jint, jint, jlong, jobject);

/*
 * Class:     com_dynamsoft_barcode_JBarcode
 * Method:    DBR_DecodeBufferRect
 * Signature: ([BIIJIIIILcom/dynamsoft/barcode/tagBarcodeResultArray;)I
 */
JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1DecodeBufferRect
  (JNIEnv *, jclass, jbyteArray, jint, jint, jlong, jint, jint, jint, jint, jobject);

/*
 * Class:     com_dynamsoft_barcode_JBarcode
 * Method:    GetErrorString
 * Signature: (I)Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_com_dynamsoft_barcode_JBarcode_GetErrorString
  (JNIEnv *, jclass, jint);

}
#endif

Add implementations in relevant CPP file. Make sure your Visual Studio can find the included header files and libraries.

#include "com_dynamsoft_barcode_JBarcode.h"

// BarcodeReaderDemo.cpp : Defines the entry point for the console application.

#include <windows.h>
#include "../../../Include/If_DBR.h"
#include "../../../Include/BarcodeFormat.h"
#include "../../../Include/BarcodeStructs.h"
#include "../../../Include/ErrorCode.h"

#ifdef _WIN64
#pragma comment(lib, "DBRx64.lib")
#else
#pragma comment(lib, "DBRx86.lib")
#endif

bool isGetClassBarcodeResult = false;
jclass    br_m_cls   = NULL;
jmethodID br_m_mid   = NULL;
jfieldID  br_m_Format = NULL;
jfieldID  br_m_BarcodeData = NULL;
jfieldID  br_m_BarcodeDataLength = NULL;
jfieldID  br_m_Left = NULL;
jfieldID  br_m_Top = NULL;
jfieldID  br_m_Width = NULL;
jfieldID  br_m_Height = NULL;
jfieldID  br_m_X1 = NULL;
jfieldID  br_m_Y1 = NULL;
jfieldID  br_m_X2 = NULL;
jfieldID  br_m_Y2 = NULL;
jfieldID  br_m_X3 = NULL;
jfieldID  br_m_Y3 = NULL;
jfieldID  br_m_X4 = NULL;
jfieldID  br_m_Y4 = NULL;
jfieldID  br_m_PageNum = NULL;

bool isGetClassBarcodeArrayResult = false;
jclass    brAry_cls   = NULL;
jmethodID brAry_mid   = NULL;
jfieldID  brAry_field_count = NULL;
jfieldID  brAry_field_brResult = NULL;

void loadJavaClassInfo(JNIEnv *env){
	if(!isGetClassBarcodeResult){
		br_m_cls   = env->FindClass("com/dynamsoft/barcode/tagBarcodeResult");
		br_m_mid   = env->GetMethodID(br_m_cls,"<init>","()V");

		br_m_Format = env->GetFieldID(br_m_cls,"lFormat","J");
		br_m_BarcodeData = env->GetFieldID(br_m_cls,"pBarcodeData","[B");
		br_m_BarcodeDataLength = env->GetFieldID(br_m_cls,"iBarcodeDataLength","I");
		br_m_Left = env->GetFieldID(br_m_cls,"iLeft","I");
		br_m_Top = env->GetFieldID(br_m_cls,"iTop","I");
		br_m_Width = env->GetFieldID(br_m_cls,"iWidth","I");
		br_m_Height = env->GetFieldID(br_m_cls,"iHeight","I");
		br_m_X1 = env->GetFieldID(br_m_cls,"iX1","I");
		br_m_Y1 = env->GetFieldID(br_m_cls,"iY1","I");
		br_m_X2 = env->GetFieldID(br_m_cls,"iX2","I");
		br_m_Y2 = env->GetFieldID(br_m_cls,"iY2","I");
		br_m_X3 = env->GetFieldID(br_m_cls,"iX3","I");
		br_m_Y3 = env->GetFieldID(br_m_cls,"iY3","I");
		br_m_X4 = env->GetFieldID(br_m_cls,"iX4","I");
		br_m_Y4 = env->GetFieldID(br_m_cls,"iY4","I");
		br_m_PageNum = env->GetFieldID(br_m_cls,"iPageNum","I");
		isGetClassBarcodeResult = true;
	}

	if(!isGetClassBarcodeArrayResult){
	    brAry_cls   = env->FindClass("com/dynamsoft/barcode/tagBarcodeResultArray");
		brAry_mid   = env->GetMethodID(brAry_cls,"<init>","()V");
		brAry_field_count = env->GetFieldID(brAry_cls,"iBarcodeCount","I");
		brAry_field_brResult = env->GetFieldID(brAry_cls,"ppBarcodes","[Lcom/dynamsoft/barcode/tagBarcodeResult;");
		isGetClassBarcodeArrayResult = true;
	}
}

jobject convertResultToJNIObject(JNIEnv *env, pBarcodeResult pBarcode){

	loadJavaClassInfo(env);

    jobject obj = env->NewObject(br_m_cls, br_m_mid);

	jbyteArray rtnbytes = env->NewByteArray((jsize)(pBarcode->iBarcodeDataLength)); 
	env->SetByteArrayRegion(rtnbytes, 0, (jsize)(pBarcode->iBarcodeDataLength), (jbyte*)pBarcode->pBarcodeData); 

	env->SetLongField(obj, br_m_Format, pBarcode->llFormat);
	env->SetObjectField(obj, br_m_BarcodeData, rtnbytes);
	env->SetIntField(obj, br_m_BarcodeDataLength, pBarcode->iBarcodeDataLength);
	env->SetIntField(obj, br_m_Left, pBarcode->iLeft);
	env->SetIntField(obj, br_m_Top, pBarcode->iTop);
	env->SetIntField(obj, br_m_Width, pBarcode->iWidth);
	env->SetIntField(obj, br_m_Height, pBarcode->iHeight);
	env->SetIntField(obj, br_m_X1, pBarcode->iX1);
	env->SetIntField(obj, br_m_Y1, pBarcode->iY1);
	env->SetIntField(obj, br_m_X2, pBarcode->iX2);
	env->SetIntField(obj, br_m_Y2, pBarcode->iY2);
	env->SetIntField(obj, br_m_X3, pBarcode->iX3);
	env->SetIntField(obj, br_m_Y3, pBarcode->iY3);
	env->SetIntField(obj, br_m_X4, pBarcode->iX4);
	env->SetIntField(obj, br_m_Y4, pBarcode->iY4);
	env->SetIntField(obj, br_m_PageNum, pBarcode->iPageNum);

	return obj;
}

void fillBarcodeResultArray(JNIEnv *env, jobject obj, pBarcodeResultArray pArrayResults){

	loadJavaClassInfo(env);

	int count = pArrayResults->iBarcodeCount;
	pBarcodeResult* ppBarcodes = pArrayResults->ppBarcodes;

	jobjectArray swArray = env->NewObjectArray(count, br_m_cls, 0); 

	for(int i=0; i<count; i++){
		env->SetObjectArrayElement(swArray, i, convertResultToJNIObject(env, ppBarcodes[i]));
	}

	env->SetIntField(obj, brAry_field_count, count);
	env->SetObjectField(obj, brAry_field_brResult, swArray);

}

void SetOptions(pReaderOptions pOption, jint option_iMaxBarcodesNumPerPage, jlong option_llBarcodeFormat){

	if(option_llBarcodeFormat > 0)
		pOption->llBarcodeFormat = option_llBarcodeFormat;
	else
		pOption->llBarcodeFormat = OneD;

	if(option_iMaxBarcodesNumPerPage > 0)
		pOption->iMaxBarcodesNumPerPage = option_iMaxBarcodesNumPerPage;
	else
		pOption->iMaxBarcodesNumPerPage = MAXINT;

}

JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1InitLicense
(JNIEnv *env, jclass, jstring pString){

	const char *nativeString = env->GetStringUTFChars(pString, 0);  

	//printf("%s", nativeString);
	int ret = DBR_InitLicense(nativeString);

	//DON'T FORGET THIS LINE!!!  
	env->ReleaseStringUTFChars(pString, nativeString);  

	return ret;
}

JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1DecodeFile
  (JNIEnv *env, jclass, jstring strFileName, jint option_iMaxBarcodesNumPerPage, jlong option_llBarcodeFormat, jobject pArrayResults)
{
	const char *pFileName = env->GetStringUTFChars(strFileName, 0);
	pBarcodeResultArray pResults = NULL;
	ReaderOptions option;
	SetOptions(&option, option_iMaxBarcodesNumPerPage, option_llBarcodeFormat);

	int ret = DBR_DecodeFile(
		pFileName,
		&option,
		&pResults
	);

	if(ret == DBR_OK){
		fillBarcodeResultArray(env, pArrayResults, pResults);
		DBR_FreeBarcodeResults(&pResults);
	}

	//DON'T FORGET THIS LINE!!!  
	env->ReleaseStringUTFChars(strFileName, pFileName);  
	return ret;
}

JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1DecodeFileRect
  (JNIEnv *env, jclass, jstring strFileName, jint option_iMaxBarcodesNumPerPage, jlong option_llBarcodeFormat, jint iRectLeft, jint iRectTop, jint iRectWidth, jint iRectHeight, jobject pArrayResults)
{
	const char *pFileName = env->GetStringUTFChars(strFileName, 0);
	pBarcodeResultArray pResults = NULL;
	ReaderOptions option;
	SetOptions(&option, option_iMaxBarcodesNumPerPage, option_llBarcodeFormat);

	int ret = DBR_DecodeFileRect(
		pFileName,
		&option,
		iRectLeft,	
		iRectTop,	
		iRectWidth,	
		iRectHeight,
		&pResults
	);

	if(ret == DBR_OK){

		fillBarcodeResultArray(env, pArrayResults, pResults);
		DBR_FreeBarcodeResults(&pResults);
	}

	//DON'T FORGET THIS LINE!!!  
	env->ReleaseStringUTFChars(strFileName, pFileName);  
	return ret;
}

JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1DecodeBuffer
  (JNIEnv *env, jclass, jbyteArray pDIBBuffer, jint iDIBSize, jint option_iMaxBarcodesNumPerPage, jlong option_llBarcodeFormat, jobject pArrayResults)
{
	pBarcodeResultArray pResults = NULL;
	ReaderOptions option;
	SetOptions(&option, option_iMaxBarcodesNumPerPage, option_llBarcodeFormat);

	int ret = DBR_DecodeBuffer(
		(unsigned char*) pDIBBuffer,		
		iDIBSize,
		&option,	
		&pResults
	);

	if(ret == DBR_OK){
		fillBarcodeResultArray(env, pArrayResults, pResults);
		DBR_FreeBarcodeResults(&pResults);
	}

	return ret;
}

JNIEXPORT jint JNICALL Java_com_dynamsoft_barcode_JBarcode_DBR_1DecodeBufferRect
  (JNIEnv *env, jclass, 
  jbyteArray pDIBBuffer, jint iDIBSize, jint option_iMaxBarcodesNumPerPage, jlong option_llBarcodeFormat, 
  jint iRectLeft, jint iRectTop, jint iRectWidth, jint iRectHeight, jobject pArrayResults)
{
	pBarcodeResultArray pResults = NULL;
	ReaderOptions option;
	SetOptions(&option, option_iMaxBarcodesNumPerPage, option_llBarcodeFormat);

	int ret = DBR_DecodeBufferRect(
		(unsigned char*) pDIBBuffer,		
		iDIBSize,
		&option,
		iRectLeft,	
		iRectTop,	
		iRectWidth,	
		iRectHeight,
		&pResults
	);

	if(ret == DBR_OK){
		fillBarcodeResultArray(env, pArrayResults, pResults);
		DBR_FreeBarcodeResults(&pResults);
	}

	return ret;
}

JNIEXPORT jstring JNICALL Java_com_dynamsoft_barcode_JBarcode_GetErrorString
  (JNIEnv *env, jclass, jint iErrorCode)
{
	const char *pError = GetErrorString( iErrorCode);
    return env->NewStringUTF(pError);
    // (*env)->ReleaseStringUTFChars(env, jstr, utf); 

}

Build the project, and copy the generated DLL and DBR DLL to the Java Barcode Reader project.

dbr java

Finally, we can specify the image file path as the argument, and run the Java project.

dbr argsdbr results

Source Code

https://github.com/dynamsoftsamples/java-barcode-reader