JNI Example

#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<jni.h>
#include<android/log.h>
#include <android_runtime/AndroidRuntime.h>
#include <JNIHelp.h>

#include "usb-unix.h"

using namespace android;

#define LOG_TAG "GenericPrintService"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)

typedef void (*update_state)(int,unsigned int);


static jobject mCallbacksObj = NULL;
static JNIEnv* Env = NULL;
static jmethodID method_reportJobState;

extern "C" int imagetops_main(int  argc,char *argv[]);
extern "C" Usb_Device_Info * getDevFile_devices();

extern "C" void update_JobState(int type, unsigned int value)
{
 jlong value_l = (jlong)(unsigned long long)value;
 
 LOGI("update_JobState type = %d, value_l = %ld",type,value_l);
 JNIEnv *env = AndroidRuntime::getJNIEnv();
 env->CallVoidMethod(mCallbacksObj, method_reportJobState, type, value_l);
}

jint Java_com_siso_app_genericprintservice_GPrintPrintingManager_InvokeIppBackend(JNIEnv* env, jobject thiz,jobjectArray stringArray){

 Env = env;
 if (!mCallbacksObj)
        mCallbacksObj = env->NewGlobalRef(thiz);
 
 jclass clazz = env->FindClass("com/siso/app/genericprintservice/GPrintPrintingManager");

 jclass glo_clazz = reinterpret_cast<jclass> (env->NewGlobalRef(clazz));
 
 method_reportJobState = env->GetMethodID(glo_clazz, "reportJobState", "(IJ)V");
  
 char *argv[100];
 int stringCount = env->GetArrayLength(stringArray);
 int i,count,lpout=0;

    for (i=0; i<stringCount; i++) {
        jstring string = (jstring) env->GetObjectArrayElement(stringArray, i);
        const char *arg = env->GetStringUTFChars(string, 0);
  argv[i] = const_cast<char *> (arg);
  LOGI("JNI InvokeIppBackend argv = %s",argv[i]);
    }
 
 lpout = ipp_main(stringCount,argv, &update_JobState, &createJavaThread);
 return lpout;


}

jobjectArray Java_com_ramesh_app_genericprintservice_GPrintPrintingManager_GetDevFileUsbDevice(JNIEnv *env, jobject thiz)
{
  Usb_Device_Info *device_info =  getDevFile_devices();
  jclass stringClazz = env->FindClass("java/lang/String");
  jobjectArray stringArray = env->NewObjectArray(3, stringClazz, NULL);

  if(device_info->device_uri != NULL)
 {
   jstring uri = env->NewStringUTF(device_info->device_uri);
   env->SetObjectArrayElement(stringArray, 0, uri);
   env->DeleteLocalRef(uri);
 } 
     
  if(device_info->make_model != NULL)
 {
   jstring model = env->NewStringUTF(device_info->make_model);
   env->SetObjectArrayElement(stringArray, 1, model);
   env->DeleteLocalRef(model);
 } 

 if(device_info->device_id != NULL)
  {
   jstring device_id = env->NewStringUTF(device_info->device_id);
   env->SetObjectArrayElement(stringArray, 2, device_id);
   env->DeleteLocalRef(device_id);
  } 
  
  return stringArray;
}

static JNINativeMethod sMethods[] = {
     /* name, signature, funcPtr */
 {"InvokeIppBackend", "([Ljava/lang/String;)I", (void *)Java_com_siso_app_genericprintservice_GPrintPrintingManager_InvokeIppBackend},
 {"GetDevFileUsbDevice", "()[Ljava/lang/String;",(void *) Java_com_ramesh_app_genericprintservice_GPrintPrintingManager_GetDevFileUsbDevice},
};


int register_android_jni_cups(JNIEnv* env)  
{ 
 jniRegisterNativeMethods(env, "com/ramesh/app/genericprintservice/GPrintPrintingManager", sMethods, NELEM(sMethods));
 
    return 0;
}

extern "C" jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
    JNIEnv* env = NULL;
    jint result = -1;

    if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {
        LOGI("JNI ERROR GetEnv failed!");
        return result;
    }
    register_android_jni_cups(env);

    return JNI_VERSION_1_4;
}

package com.ramesh.app.genericprintservice;

public class GPrintPrintingManager {

    static {
        try {
            System.loadLibrary("invCupsjni");

        } catch (Exception ex) {
            Log.i("GPrintPrintingManager", "Cannot load library" + ex.toString());
        }
    }

 //Native methods
    private native String[] GetDevFileUsbDevice();
    private native int InvokeIppBackend(String[] lpCommand);

 //Callback from Native
    public void reportJobState(int type, long value) {
  
    }
 
 private void sendToUSB() {

        String dev[] = GetDevFileUsbDevice();

 }


    private int sendToIpp() {

        String[] linesArr1 = {};
        int ret = InvokeIppBackend(linesArr1);

        return ret;
    }
}