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.
JNI for Linking Dynamsoft Barcode Reader DLL
Download and install Dynamsoft Barcode Reader.
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.
Add Library directories of DBR.
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.
Finally, we can specify the image file path as the argument, and run the Java project.
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