jni方式分两种
1、JNIEXPORT jint JNICALL java调用loadLibrary处包名加方法名
2、JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved)中指定包名
第二种方法需要注意在头文件中进行定义
方法一示例：
jni代码
// jni实现
JNIEXPORT static jint Native_API_Led_turnOn(JNIEnv * env, jobject obj,jint paramInt){
return 0;
}
//映射关系
static JNINativeMethod getMethods[] = {
{"ApiLedTurnOn","(I)I",(void*)Native_API_Led_turnOn},
};
static int registerNatives(JNIEnv* env){
//指定类的路径，通过FindClass 方法来找到对应的类
const char* className = "com/lhxx/jni/server/PrivateAPIWrapper";
return registerNativeMethods(env,className,getMethods, sizeof(getMethods)/ sizeof(getMethods[0]));
}
JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved){
JNIEnv* env = NULL;
//判断虚拟机状态是否有问题
if((*vm)->GetEnv(vm,(void**)&env,JNI_VERSION_1_4)!= JNI_OK){
return -1;
}
assert(env != NULL);
//开始注册函数 registerNatives -》registerNativeMethods -》env->RegisterNatives
if(!registerNatives(env)){
return -1;
}
//返回jni 的版本
return JNI_VERSION_1_4;
}
java代码
package com.lhxx.jni.server;
public class PrivateAPIWrapper {
public PrivateAPIWrapper(){
}
static{
System.loadLibrary("jni_lhxx_server");
}
public static native int ApiLedTurnOn(int paramInt);
}
Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE := libjni_test
LOCAL_LDLIBS += -llog -ldl
LOCAL_SHARED_LIBRARIES := libutils
LOCAL_SRC_FILES := \
jni_lhxx_server.c
LOCAL_C_INCLUDES += \
$(JNI_H_INCLUDE)
include $(BUILD_SHARED_LIBRARY)
方法二示例：
java代码
public class JNIExtPrinter {
static {
System.loadLibrary("config_ext_printer");
}
public native int nativeConfig4gethernet(int onOff); // 0:off others:on
public JNIExtPrinter() {
// TODO Auto-generated constructor stub
}
}
jni代码
config_extprinter.c文件
#include "config_extprinter.h"
#include <stdlib.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <utils/Log.h>
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG,LOG_TAG,__VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
JNIEXPORT jint JNICALL Java_com_android_settings_JNIExtPrinter_nativeConfig4gethernet{
return 0;
}
config_extprinter.h文件
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: Java_com_android_settings_JNIExtPrinter
* Method: nativeConfigExtPrinter
* Signature: (I)I
*/
JNIEXPORT jint JNICALL Java_com_android_settings_JNIExtPrinter_nativeConfig4gethernet
(JNIEnv *, jobject, jint);
#ifdef __cplusplus
}
#endif
#endif
Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE := libconfig_ext_printer
LOCAL_LDLIBS += -llog
LOCAL_SHARED_LIBRARIES := libutils
LOCAL_SRC_FILES := \
config_extprinter.cpp
LOCAL_C_INCLUDES += \
$(JNI_H_INCLUDE) \
include $(BUILD_SHARED_LIBRARY)
