基于ndk jni技术实现串口收发的方法

//*******************java jni类*************************//
package com.example.hellojni;

public class JniInterface {

static {
System.loadLibrary("hello-jni");//可装载java.library.path包含路径下的so
// System.load("/sdcard/mylib/libhello-jni.so");//可装载任何绝对路径的so
}

//串口初始化
public static native void CommInit();

//串口收发
public static native int ComSendRecv(byte[] inBuf,int nInLen,byte[] outBuf);

public static native void nativeInit();

//下面两个是测试jni里面调用java方法
public static native void nativeExecution();

private  static void DispInfo(int value)
{
System.out.println("this is called by c value:"+value);
//Toast.makeText(mainContext, "this is from c:"+value,Toast.LENGTH_LONG).show();
}
}
//*********************javah生成.h****************************//
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_example_hellojni_JniInterface */

#ifndef _Included_com_example_hellojni_JniInterface
#define _Included_com_example_hellojni_JniInterface
#ifdef __cplusplus
extern "C" {
#endif

/*
* Class:     com_example_hellojni_JniInterface
* Method:    CommInit
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_example_hellojni_JniInterface_CommInit
(JNIEnv *, jobject);

/*
* Class:     com_example_hellojni_JniInterface
* Method:    ComSendRecv
* Signature: ([BI[B)I
*/
JNIEXPORT jint JNICALL Java_com_example_hellojni_JniInterface_ComSendRecv
(JNIEnv *, jobject, jbyteArray, jint, jbyteArray);

/*
* Class:     com_example_hellojni_JniInterface
* Method:    nativeInit
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_example_hellojni_JniInterface_nativeInit
(JNIEnv *, jobject);

/*
* Class:     com_example_hellojni_JniInterface
* Method:    nativeExecution
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_example_hellojni_JniInterface_nativeExecution
(JNIEnv *, jobject);

#ifdef __cplusplus
}
#endif
#endif
//*********************实现对应.c****************************//
#include"com_example_hellojni_JniInterface.h"

void Java_com_example_hellojni_JniInterface_CommInit(JNIEnv* env,jobject thiz)
{
Comm_Init();//这里面就是linux c串口初始化代码，如打开串口，设置波特率，阻塞等
}

int _ComSendRecvPack(unsigned char *psInBuf,unsigned int nInLen,unsigned char *psOutBuf)
{
unsigned char ucmRetCmdNo[2];
int i=0;
int nTagCount=0;//tag个数

//发送
m_SendBufLen = nInLen;
memset(m_SendBuf,0,sizeof(m_SendBuf));
memcpy(m_SendBuf,psInBuf,nInLen);

ComSend();//里面是串口write

//接收
ComRecv();//里面是串口read
memcpy(psOutBuf,m_RecvBuf,m_RecvBufLen);

return m_RecvBufLen;

}
//串口封装给JNI
int Java_com_example_hellojni_JniInterface_ComSendRecv(JNIEnv* env,jobject thiz,jbyteArray psInBuf,int nInLen,jbyteArray psOutBuf)
{
jbyte native_Inbuf[1024];
jbyte native_Outbuf[1024];
jint nlen = 0;

//类型转换java byte -> c buf
(*env)->GetByteArrayRegion(env,psInBuf,0,nInLen,native_Inbuf);

nlen = _ComSendRecvPack(native_Inbuf,nInLen,native_Outbuf);

//c buf -> java byte
(*env)->SetByteArrayRegion(env,psOutBuf,0,nlen,native_Outbuf);

return nlen;
}
jmethodID gOnNativeID;
JNIEnv* genv;
jobject mObject;
jclass mClass;
JavaVM* gs_jvm;

//native初始化函数
void Java_com_example_hellojni_JniInterface_nativeInit(JNIEnv* env,jobject thiz)
{

printf("CalledForJni_nativeInit................");

//获取类
jclass clazz = (*env)->FindClass(env,"com/example/hellojni/JniInterface");
if(clazz==NULL)
{
printf("clazz IS NULL................");
return;
}
//mClass = (jclass)(*env)->NewGlobalRef(env,clazz);//永久保存mClass

mObject = (jobject)(*env)->NewGlobalRef(env,thiz);
//获取方法ID
gOnNativeID = (*env)->GetStaticMethodID(env,clazz,"DispInfo","(I)V");
if(gOnNativeID==NULL)
{
printf("gOnNativeID IS NULL................");
return;
}
//得到JAVA VM，为了在其他没有传env参数的函数获取env调用java方法
(*env)->GetJavaVM(env,&gs_jvm);
printf("CalledForJni_nativeInit end................");

}
void Java_com_example_hellojni_JniInterface_nativeExecution(JNIEnv* env,jobject thiz)
{
printf("nativeExecution................");
(*env)->CallStaticVoidMethod(env,mObject,gOnNativeID);
(*env)->DeleteGlobalRef(env,mObject);
return;
}

//*********************activity部分****************************//
JniInterface.CommInit();

serialtestbutton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
//Log.i(HelloJni.ACTIVITY_TAG,"serialtestbutton clicked================");

Log.i(HelloJni.ACTIVITY_TAG,"inBuf："+nInLen+":"+ByteTool.getHexString(inBuf));

Log.i(HelloJni.ACTIVITY_TAG,"before send");
nOutLen = JniInterface.ComSendRecv(inBuf, nInLen, outBuf);
Log.i(HelloJni.ACTIVITY_TAG,"after recv");

byte[] temp = new byte[nOutLen];
System.arraycopy(outBuf, 0, temp, 0, nOutLen);
Log.i(HelloJni.ACTIVITY_TAG,"outBuf："+nOutLen+":"+ByteTool.getHexString(temp));
}
});