C代码:
(*env)->FindClass("org/pthreadClass");
而C++代码:
env->FindClass("org/pthreadClass");具体原因可以自行查找,大致思想是jni已经做了C和C++的区分,所以要注意他们的书写方式.

#include "onload.h"
#include <android/log.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <string.h>
#define TAG "jni_thread"
#define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO,TAG,__VA_ARGS__))
#define LOGW(...) ((void)__android_log_print(ANDROID_LOG_WARN,TAG,__VA_ARGS__))
#define LOGE(...) ((void)__android_log_print(ANDROID_LOG_ERROR,TAG,__VA_ARGS__))extern int register_android_pthread_jni_demo(JNIEnv* env);JavaVM* mEnv;JavaVM* getJNIVM(){JavaVM* env=NULL;if(mEnv->GetEnv((void**)&env,JNI_VERSION_1_4)){return NULL;}return env;}
int jniRegisterNativeMethods(JNIEnv* env,const char* classname,const JNINativeMethod* gMethods,int numMethods){jclass classz;classz=env->FindClass(classname);if(classz==NULL){return JNI_ERR;}if(env->RegisterNatives(classz,gMethods,numMethods)<0){return JNI_ERR;}return JNI_OK;}
int jniThrowExeption(JNIEnv *env,const char* classname){jclass classz;classz=env->FindClass(classname);if(classz==NULL){return JNI_ERR;}return JNI_OK;}
jint JNI_OnLoad(JavaVM *vm, void *reserved){JNIEnv* env=NULL;jint result=JNI_ERR;mEnv=vm;if(vm->GetEnv((void**)&env,JNI_VERSION_1_4)!=JNI_OK){return result;}if(register_android_pthread_jni_demo(env)!=JNI_OK){goto end;//will not continue register others native methods//goto end at once
    }return JNI_VERSION_1_4;end:return result;}

#include<jni.h>
#ifndef _ON_LOAD_HEADER_H__
#define _ON_LOAD_HEADER_H__JavaVM* getJNIVM();
int jniRegisterNativeMethods(JNIEnv* env,const char* classname,const JNINativeMethod* gMethods,int numMethods);
int jniThrowExeption(JNIEnv *env,const char* classname);
jint JNI_OnLoad(JavaVM *vm, void *reserved);#endif

#include <jni.h>
#include <android/log.h>
#include <pthread.h>#include "onload.h"#define TAG "jni_thread"#define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO,TAG,__VA_ARGS__))
#define LOGW(...) ((void)__android_log_print(ANDROID_LOG_WARN,TAG,__VA_ARGS__))
#define LOGE(...) ((void)__android_log_print(ANDROID_LOG_ERROR,TAG,__VA_ARGS__))
#define NUMT 5
#define JAVA_CLASS_PATH "org/pthreadClass"
namespace android{void native_init(){LOGI("native init .");}void* fun_in_thread(void* arg){LOGI("enter in fun_in_thread !");}void main_pThread(){LOGI("MAIN THREAD");pthread_t pt[NUMT];int i;for(i=0;i<NUMT;i++){pthread_create(&pt[i],NULL,&fun_in_thread,(void*)i);}}}using namespace android;JNINativeMethod mNativeMethods[]={{"nativeinit","()V",(void*)native_init},{"mainthread","()V",(void*)main_pThread}
};int register_android_pthread_jni_demo(JNIEnv* env){return jniRegisterNativeMethods(env,JAVA_CLASS_PATH,mNativeMethods,sizeof(mNativeMethods)/sizeof(mNativeMethods[0]));}

pthread_create(&pt[i],NULL,&fun_in_thread,(void*)i);

参数说明:
第一个参数为指向线程标识符的指针。 第二个参数用来设置线程属性。 第三个参数是线程运行函数的起始地址。 最后一个参数是运行函数的参数

LOCAL_PATH    :=$(call my-dir)
include $(CLEAR_VARS)LOCAL_MODULE    := threadlibLOCAL_SRC_FILES    := onload.cpp pthreadClass.cppLOCAL_SHARED_LIBRARY := libnativehelper liblog
#下面一句cflags可以不需要
LOCAL_CFLAGS := -llog -lpthread
#添加log的
LOCAL_LDLIBS    :=-lloginclude $(BUILD_SHARED_LIBRARY)