Android的JNI技术

1.Jni层调用java层函数，产生回调

2.数组在C/C++层、jni层、java层之间的传递

3.C/C++层、jni层、java之间函数的调用与参数的传递

4.C++面向对象

5.使用JNI_OnLoad

 

package com.example.test1;//javah com.example.test.XTNative 生成jni层的.h文件public class XTNative{static {try {System.loadLibrary("a");System.loadLibrary("b");System.loadLibrary("Test1");} catch (UnsatisfiedLinkError e) {// TODO: handle exceptione.printStackTrace();}}public static native void XTSetMainHwnd(long mhwnd);//传入long类型参数public static native String XTSetMainHwnd();//返回String类型public static native long getLongName(long mhwnd);//返回long类型//传入一个接口，让jni层调用java层的函数，并且回调在Java层使用参数public static native void setCallbackOnTellLocalIDs(JKCallBack oncj,int a, int b);public static native void operateArray(int []array,int length);//传入数组public static native void operateString(String string);//传入String类型参数public static native int[] operateIntArray(int []array,int length);//传入数组，返回数组} package com.example.test1;public interface JKCallBack {void callback(int a,int b);void callback(int a,int b, int c);}package com.example.test1;import android.app.Activity;import android.opengl.GLSurfaceView;import android.os.Bundle;import android.view.View;import android.widget.Button;public class MainActivityextends Activity implements JKCallBack{ View view;Button button;int []array = {1,52,441,63,55};int []JniArray;GLSurfaceView a;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_list_item);        XTNative.XTSetMainHwnd(100000000);        System.out.println("+++++" + XTNative.XTSetMainHwnd());        System.out.println("+++++" + XTNative.getLongName(520));        XTNative.setCallbackOnTellLocalIDs(this, 10, 20);        XTNative.operateArray(array,array.length);        XTNative.operateString("chenhanhere");        JniArray = XTNative.operateIntArray(array,array.length);        for(int i = 0; i <JniArray.length; i++){         System.out.println("+++++" +JniArray[i]);        }    }@Overridepublic void callback(int a,int b){// TODO 自动生成的方法存根System.out.println("vadaweeeeaa:" + (a+b));}@Overridepublic void callback(int a,int b, int c){// TODO 自动生成的方法存根System.out.println("a b c :" + (a+b));}} com_example_test1_XTNative.h#include <jni.h>/* Header for class com_example_test1_XTNative */ #ifndef _Included_com_example_test1_XTNative#define _Included_com_example_test1_XTNative#ifdef __cplusplusextern "C" {#endif/* * Class:     com_example_test1_XTNative * Method:    XTSetMainHwnd * Signature: (J)V */JNIEXPORT void JNICALL Java_com_example_test1_XTNative_XTSetMainHwnd__J  (JNIEnv *, jclass, jlong); /* * Class:     com_example_test1_XTNative * Method:    XTSetMainHwnd * Signature: ()Ljava/lang/String; */JNIEXPORT jstring JNICALL Java_com_example_test1_XTNative_XTSetMainHwnd__  (JNIEnv *, jclass); /* * Class:     com_example_test1_XTNative * Method:    getLongName * Signature: (J)J */JNIEXPORT jlong JNICALL Java_com_example_test1_XTNative_getLongName  (JNIEnv *, jclass, jlong); /* * Class:     com_example_test1_XTNative * Method:    setCallbackOnTellLocalIDs * Signature: (Lcom/example/test1/JKCallBack;II)V */JNIEXPORT void JNICALL Java_com_example_test1_XTNative_setCallbackOnTellLocalIDs  (JNIEnv *, jclass, jobject, jint, jint); /* * Class:     com_example_test1_XTNative * Method:    operateArray * Signature: ([II)V */JNIEXPORT void JNICALL Java_com_example_test1_XTNative_operateArray  (JNIEnv *, jclass, jintArray, jint); /* * Class:     com_example_test1_XTNative * Method:    operateString * Signature: (Ljava/lang/String;)V */JNIEXPORT void JNICALL Java_com_example_test1_XTNative_operateString  (JNIEnv *, jclass, jstring); /* * Class:     com_example_test1_XTNative * Method:    operateIntArray * Signature: ([II)[I */JNIEXPORT jintArray JNICALL Java_com_example_test1_XTNative_operateIntArray  (JNIEnv *, jclass, jintArray, jint); #ifdef __cplusplus}#endif#endif Test1.cpp#include <jni.h>#include "com_example_test1_XTNative.h"#include <android/log.h>#include <string.h>#include "inc/a.h"#include "inc/incjia/b.h" void JNICALL Java_com_example_test1_XTNative_XTSetMainHwnd__J  (JNIEnv * env, jclass cls, jlong mhwnd){int i = 50;__android_log_print(4, "test_xt", "mhwnd:%d", i);__android_log_print(4,"OnLinkServer_callback","sNum=%d,bz=%d",i,i);} jstring JNICALL Java_com_example_test1_XTNative_XTSetMainHwnd__  (JNIEnv * env, jclass cls){ jstring szsIDS=env->NewStringUTF("AAAAAA");return szsIDS; } jlong JNICALL Java_com_example_test1_XTNative_getLongName  (JNIEnv * env, jclass cls, jlong mhwnd){ long pwd = mhwnd + 700;return pwd;} void JNICALL Java_com_example_test1_XTNative_setCallbackOnTellLocalIDs  (JNIEnv * env, jclass cls, jobject obj, jint a, jint b){ jclass jls = env->GetObjectClass(obj);//获得传入的obj__android_log_print(4, "call", "back");jmethodID callback = env->GetMethodID(jls, "callback", "(III)V");//获得obj里面的callback方法env->CallVoidMethod(obj, callback, a, add(a, b));//返回java层调用函数的参数__android_log_print(4, "call", "back");printHello(); } void JNICALL Java_com_example_test1_XTNative_operateArray  (JNIEnv * env, jclass cls, jintArray array, jint length){__android_log_print(4, "array", "length=%d", length);jint nativeaArray[length];env->GetIntArrayRegion(array, 0, length, nativeaArray);//env->ReleaseIntArrayElements(array, nativeaArray, 0);for(int i = 0; i < length; i++) {__android_log_print(4, "array", "nativeaArray[%d]=%d", i, nativeaArray[i]);}} void JNICALL Java_com_example_test1_XTNative_operateString  (JNIEnv * env, jclass cls, jstring str){int a = env->GetStringLength(str);jboolean isCopy = true;int c = min(100, 50);const jchar *chars = env->GetStringChars(str, &isCopy); __android_log_print(4, "aaa", "str length = %d", a);__android_log_print(4, "aaa", "chars = %s", chars);} jintArray JNICALL Java_com_example_test1_XTNative_operateIntArray(JNIEnv * env, jclass cls , jintArray array, jint length){jint nativeaArray[length];env->GetIntArrayRegion(array, 0, length, nativeaArray); arrayC(nativeaArray, length); for(int i = 0; i < length; i++) {nativeaArray[i] = 1 + nativeaArray[i];__android_log_print(4, "array", "nativeaArray[%d]=%d", i, nativeaArray[i]); } env->SetIntArrayRegion(array, 0, length, nativeaArray);Light *led = LightNew();led->turnOn(led);led->turnOff(led);__android_log_print(4, "led", "led status=%d", led->state);//env->ReleaseIntArrayElements(array, nativeaArray, 0); Student stu;stu.age = 100;__android_log_print(4, "Student", "Student age=%d", stu.age);stu.say(stu);return array;} Android.mkLOCAL_PATH := $(call my-dir)JNI_PATH := $(LOCAL_PATH)include $(CLEAR_VARS) LOCAL_MODULE    := Test1LOCAL_SRC_FILES := Test1.cpp LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -L$(ANDROID_LIB)/ -llog -landroid LOCAL_SHARED_LIBRARIES := a binclude $(BUILD_SHARED_LIBRARY)include $(JNI_PATH)/inc/Android.mkinclude $(JNI_PATH)/inc/incjia/Android.mk a.h/* * a.h * *  Created on: 2016年6月14日 *      Author: chenhan */ #ifndef C_H_#define C_H_#include <stdio.h>#include <malloc.h> void printHello();int add(int a,int b);void printChars(char *chars);int min(int a,int b);int *arrayOperate(int arr[],int length);void arrayC(int *p,int length); struct Light{int state;void (*turnOn)(Light*);void (*turnOff)(Light*);};typedef struct Light Light; static void turnOn(Light *cobj);static void turnOff(Light *cobj); struct Light *LightNew(); #endif /* C_H_ */ a.cpp#include "a.h"#include <android/log.h>void printHello(){__android_log_print(4, "printHello", "printHello");} int add(int a,int b){return (a*b);} void printChars(char *chars){__android_log_print(4, "char", "");}int min(int a,int b){return (a-b);} int *arrayOperate(int arr[],int length){for(int i = 0; i < length; i++){arr[i] = arr[i] + 100;}return arr;} void arrayC(int *p,int length){for(int i = 0; i < length; i++){__android_log_print(4, "array", "+++++%d", p[i]);p[i] = p[i] + 100;}} static void turnOn(Light *cobj){cobj->state = 1;__android_log_print(4, "array", "+++++on++%d", cobj->state);}static void turnOff(Light *cobj){cobj->state = 0;__android_log_print(4, "array", "+++++off++%d", cobj->state);} struct Light *LightNew(){// 構造式struct Light *t;t = (Light *)malloc(sizeof(Light));t->turnOn = turnOn;t->turnOff = turnOff;return t;} a对应的Android.mk文件LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE    := aLOCAL_SRC_FILES := a.cpp LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -L$(ANDROID_LIB)/ -llog -landroidinclude $(BUILD_SHARED_LIBRARY) b.h/* * b.h * *  Created on: 2016年8月18日 *      Author: chenhan */ #ifndef B_H_#define B_H_#include <stdio.h> typedef void          Student_Say; class Student {public :int age;int source;public :Student_Say say(Student stu);}; #endif /* B_H_ */ b.cpp/* * b.cpp * *  Created on: 2016年8月18日 *      Author: chenhan */ #include "b.h"#include <android/log.h> Student_Say Student::say(Student stu){__android_log_print(4, "C++ printHello","C++ say Hello + %d", stu.age);} b对应的Android.mk文件LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE    := bLOCAL_SRC_FILES := b.cpp LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -L$(ANDROID_LIB)/ -llog -landroidinclude $(BUILD_SHARED_LIBRARY) //在Test1.cpp文件加上如下代码可以不需要com_example_test1_XTNative.h文件JavaVM* g_vm;static JNINativeMethod gMethods[] = {{"XTSetMainHwnd",      "(J)",        (void *)XTSetMainHwnd},{"XTSetMainHwnd","()Ljava/lang/String;",(void*)XTSetMainHwnd},{"getLongName","(J)J",(void*)getLongName},{"setCallbackOnTellLocalIDs","(Lcom/example/test1/JKCallBack;II)V",(void*)setCallbackOnTellLocalIDs},{"operateArray","([II)V",(void*)operateArray},{"operateString","(Ljava/lang/String;)V",(void*)operateString},{"operateIntArray","([II)[I",(void*)operateIntArray},}; static const char*const kClassPathName ="com/xtmedia/xtsip/SipNative";#define NELEM(x) ((int) (sizeof(x) /sizeof((x)[0])))// This function only registers the native methodsstatic int register_android_xt_sip(JNIEnv *env){return AndroidRuntime::registerNativeMethods(env,kClassPathName, gMethods, NELEM(gMethods));} jint JNI_OnLoad(JavaVM* vm, void* reserved){JNIEnv* env = NULL;jint result = -1;g_vm = vm;if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {// ALOGE("ERROR: GetEnv failed\n");goto bail;}//   assert(env != NULL); //    g_vm = vm;if (register_android_xt_sip(env) < 0) {//ALOGE("ERROR: MediaPlayer native registration failed\n");__android_log_print(ANDROID_LOG_ERROR,  "JNI_OnLoad" ,"ERROR: MediaPlayer native registration failed\n");goto bail;}__android_log_print(ANDROID_LOG_ERROR,  "JNI_OnLoad" ,"success -- return valid version number\n");/* success -- return valid version number */result = JNI_VERSION_1_4; bail:return result;}