[RK3399][Android7.1] 调试笔记 --- 串口JNI测试用例
Platform: RK3399
OS: Android 7.1
Kernel: v4.4.83
Android并没有包含串口的JNI， 需要我们自己实现。(Android Thing已经有实现)
串口JNI的参考范例见： https://github.com/cepr/android-serialport-api。
有将它修改做了实现，也分享给大家做参考。
JNI部分：
SerialPort.c
/*
* Copyright 2009-2011 Cedric Priscal
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include " , "()V");
jfieldID descriptorID = (*env)->GetFieldID(env, cFileDescriptor, "descriptor", "I");
mFileDescriptor = (*env)->NewObject(env, cFileDescriptor, iFileDescriptor);
(*env)->SetIntField(env, mFileDescriptor, descriptorID, (jint)fd);
}
LOGE("Java_com_example_serialport_SerialPort_open");
return mFileDescriptor;
}
/*
* Class: cedric_serial_SerialPort
* Method: close
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_example_serialport_SerialPort_close
(JNIEnv *env, jobject thiz)
{
jclass SerialPortClass = (*env)->GetObjectClass(env, thiz);
jclass FileDescriptorClass = (*env)->FindClass(env, "java/io/FileDescriptor");
jfieldID mFdID = (*env)->GetFieldID(env, SerialPortClass, "mFd", "Ljava/io/FileDescriptor;");
jfieldID descriptorID = (*env)->GetFieldID(env, FileDescriptorClass, "descriptor", "I");
jobject mFd = (*env)->GetObjectField(env, thiz, mFdID);
jint descriptor = (*env)->GetIntField(env, mFd, descriptorID);
LOGD("close(fd = %d)", descriptor);
close(descriptor);
}SerialPort.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include 编译成so
Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := libserialport
LOCAL_SRC_FILES := SerialPort.c
LOCAL_SHARED_LIBRARIES := liblog libcutils
include $(BUILD_SHARED_LIBRARY)测试程序：
Java调用JNI部分：
SerialPort.java
package com.example.serialport;
import android.util.Log;
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* Created by kris on 8/16/18.
*/
public class SerialPort {
private static final String TAG = "SerialPort";
private FileDescriptor mFd;
private FileInputStream mFileInputStream;
private FileOutputStream mFileOutputStream;
public void onDataReceived(final byte[] buffer, final int size) {
//事件处理很多或者耗时的话可以开个线程
/* new Thread(new Runnable() {
@Override
public void run() {
//do sth.
Log.i(TAG, "onDataReceived: ");
}
}).start();*/
}
// protected abstract void onDataReceived(final byte[] buffer, final int size);
public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException {
mFd = open(device.getAbsolutePath(), baudrate, flags);
if (mFd == null) {
Log.e(TAG, "native open returns null");
throw new IOException();
}
mFileInputStream = new FileInputStream(mFd);
mFileOutputStream = new FileOutputStream(mFd);
//开一个线程实时接收串口数据
new Thread(new Runnable() {
@Override
public void run() {
while (true) {
int size;
try {
byte[] buffer = new byte[64];
if (mFileInputStream == null) return;
size = mFileInputStream.read(buffer);
//数据处理
onDataReceived(buffer, size);
} catch (IOException e) {
e.printStackTrace();
return;
}
}
}
}).start();
}
public int Send(final byte[] buffer, final int size)
{
try {
if (mFileOutputStream != null) {
mFileOutputStream.write(buffer);
} else {
return 0;
}
} catch (IOException e) {
e.printStackTrace();
}
return 1;
}
// Getters and setters
public InputStream getInputStream() {
return mFileInputStream;
}
public OutputStream getOutputStream() {
return mFileOutputStream;
}
// JNI
private native static FileDescriptor open(String path, int baudrate, int flags);
public native void close();
static {
System.loadLibrary("serialport");
}
}打开串口
ExternalDevices.java
package com.example.serialport;
import java.io.File;
import java.io.IOException;
/**
* Created by kris on 8/20/18.
*/
public class ExternalDevices {
private static final String TAG = "ExternalDevices";
public SerialPort mSerialPort = null;
public ExternalDevices()
{
try {
mSerialPort = new SerialPort(new File("/dev/ttyS4"), 115200, 0);
}catch (IOException e){}
}
}完整的测试见： https://download.csdn.net/download/kris_fei/10637861