基于Linux的JNI动态函数注册
cmake_minimum_required(VERSION 3.2)
project(AlgorithmLibrary)
set(ProjectDir ${CMAKE_CURRENT_SOURCE_DIR})
set(LIBRARY_OUTPUT_PATH ${ProjectDir}/lib)
set(DynamicRegisterDir ${CMAKE_CURRENT_SOURCE_DIR}/DynamicRegister/)
include_directories(
./include /opt/jdk1.8.0_201/include/
${DynamicRegisterDir}
TimeComplexity/
Test/
)
add_library(
AlgorithmLibrary SHARED
${DynamicRegisterDir}/DynamicRegisterMethod.cpp
TimeComplexity/InstrucNumTime.cpp
Test/Test.cpp
)
动态函数注册核心代码
#ifndef DynamicRegisterMethod
#define DynamicRegisterMethod
#include <Common.h>
#include <InstrucNumTime.h>
#include <Test.h>
#endif
#include <DynamicRegisterMethod.h>
using namespace std;
char* javaClass [] = {
(char*)"com/ossit/demo01/App",
};
static JNINativeMethod getMethod[1][2] = {
{
{(char*)"printInstructionTime",(char*)"()V",(void*)printInstructionTime},
{(char*)"test",(char*)"()V",(void*)test}
}
};
int registerNativeMethods(JNIEnv* env,const char* name,
JNINativeMethod* methods,jint nmethods){
jclass jcls;
jcls = env->FindClass(name);
if(jcls == NULL) {
return JNI_FALSE;
}
if(env->RegisterNatives(jcls,methods,nmethods) < 0){
return JNI_FALSE;
}
return JNI_TRUE;
}
JNIEXPORT int JNICALL JNI_OnLoad(JavaVM* vm,void* reserved){
JNIEnv* env;
if(vm->GetEnv(reinterpret_cast<void**>(&env),JNI_VERSION_1_6) != JNI_OK){
return JNI_FALSE;
}
int count=0;
for(int i=0;i < sizeof(javaClass)/sizeof(javaClass[0]);i++){
for(int j=0;j< sizeof(getMethod[i])/sizeof(getMethod[i][0]);j++){
if(getMethod[i][j].fnPtr != NULL){
count++;
}
}
registerNativeMethods(env,javaClass[i],&getMethod[i][0],count);
count = 0;
}
cout << "LoadAlgorithmLibrary" << endl;
return JNI_VERSION_1_6;
}
#ifndef Common
#define Common
#include <jni.h>
#include <iostream>
#include <stdio.h>
#endif
#ifndef Test
#define Test
#include <Common.h>
void test();
#endif
#include <Test.h>
void test(){
int l;
short s;
char c;
l = 0xabcddcba;
s = l;
c = l;
printf("宽度溢出\n");
printf("l = 0x%x (%d bits)\n", l, sizeof(l) * 8);
printf("s = 0x%x (%d bits)\n", s, sizeof(s) * 8);
printf("c = 0x%x (%d bits)\n", c, sizeof(c) * 8);
printf("整型提升\n");
printf("s + c = 0x%x (%d bits)\n", s+c, sizeof(s+c) * 8);
}
#include <InstrucNumTime.h>
#include <cmath>
#include <ctime>
using namespace std;
/**
*
* 计算机处理指令数的时间
*
**/
void printInstructionTime(){
for(jint i=1;i<=9;i++){
jint number = pow(10,i);
clock_t startTime = clock();
jint sum = 0;
for(jint j=0;j<number;j++){
sum += j;
}
clock_t endTime = clock();
cout << "10^" << i << " : " << (jdouble)(endTime-startTime)/CLOCKS_PER_SEC << "s" << endl;
}
}
#ifndef InstrucNumTime
#define InstrucNumTime
#include <Common.h>
void printInstructionTime();
#endif
