【Android】串口通信

jni部分SerialPort.c

JNIEXPORT jobject JNICALL Java_android_serialport_SerialPort_open  (JNIEnv *env, jobject thiz, jstring path, jint baudrate){int fd;speed_t speed;jobject mFileDescriptor;/* Check arguments */{speed = getBaudrate(baudrate);if (speed == -1) {/* TODO: throw an exception */LOGE("Invalid baudrate");return NULL;}}/* Opening device */{jboolean iscopy;const char *path_utf = (*env)->GetStringUTFChars(env, path, &iscopy);LOGD("Opening serial port %s", path_utf);//fd = open(path_utf, O_RDWR | O_DIRECT | O_SYNC);fd = open(path_utf, O_RDWR | O_SYNC);LOGD("open() fd = %d", fd);(*env)->ReleaseStringUTFChars(env, path, path_utf);if (fd == -1){/* Throw an exception */LOGE("Cannot open port");/* TODO: throw an exception */return NULL;}}/* Configure device */{struct termios cfg;LOGD("Configuring serial port");if (tcgetattr(fd, &cfg)){LOGE("tcgetattr() failed");close(fd);/* TODO: throw an exception */return NULL;}cfmakeraw(&cfg);cfsetispeed(&cfg, speed);cfsetospeed(&cfg, speed);if (tcsetattr(fd, TCSANOW, &cfg)){LOGE("tcsetattr() failed");close(fd);/* TODO: throw an exception */return NULL;}}/* Create a corresponding file descriptor */{jclass cFileDescriptor = (*env)->FindClass(env, "java/io/FileDescriptor");jmethodID iFileDescriptor = (*env)->GetMethodID(env, cFileDescriptor, "<init>", "()V");jfieldID descriptorID = (*env)->GetFieldID(env, cFileDescriptor, "descriptor", "I");mFileDescriptor = (*env)->NewObject(env, cFileDescriptor, iFileDescriptor);(*env)->SetIntField(env, mFileDescriptor, descriptorID, (jint)fd);}return mFileDescriptor;}/* * Class:     cedric_serial_SerialPort * Method:    close * Signature: ()V */JNIEXPORT void JNICALL Java_android_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);}

Java代码部分

SerialPort.java

/* * Copyright 2009 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.  */package android.serialport;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;import android.util.Log;public class SerialPort {private static final String TAG = "SerialPort";/* * Do not remove or rename the field mFd: it is used by native method close(); */private FileDescriptor mFd;private FileInputStream mFileInputStream;private FileOutputStream mFileOutputStream;public SerialPort(File device, int baudrate) throws SecurityException, IOException {Log.i("chw", "SerialPort ---> SerialPort");/* Check access permission */if (!device.canRead() || !device.canWrite()) {/*try {// Missing read/write permission, trying to chmod the file Process su;su = Runtime.getRuntime().exec("/system/bin/su");//String cmd = "chmod 777 " + device.getAbsolutePath() + "\n"//+ "exit\n";String cmd = "chmod 777 /dev/s3c_serial0" + "\n"+ "exit\n";su.getOutputStream().write(cmd.getBytes());if ((su.waitFor() != 0) || !device.canRead()|| !device.canWrite()) {throw new SecurityException();}} catch (Exception e) {e.printStackTrace();throw new SecurityException();}*/try {              String command = "chmod 777 " + device.getAbsolutePath();              Log.i("chw", "command = " + command  + "\ndevice.getAbsolutePath = " + device.getAbsolutePath());              Runtime runtime = Runtime.getRuntime();                Process proc = runtime.exec(command);             } catch (IOException e) {          Log.i("chw","chmod fail!!  !!");              e.printStackTrace(); throw new SecurityException();         }        Log.i("chw", "Get serial port read/write   permission");}mFd = open(device.getAbsolutePath(), baudrate);if (mFd == null) {Log.e(TAG, "native open returns null ");throw new IOException();}mFileInputStream = new FileInputStream(mFd);mFileOutputStream = new FileOutputStream(mFd);}// Getters and setterspublic InputStream getInputStream() {Log.i("chw", "SerialPort ---> getInputStream");return mFileInputStream; }public OutputStream getOutputStream() {Log.i("chw", "SerialPort ---> getOutputStream");return mFileOutputStream;  }// JNIprivate native static FileDescriptor open(String path, int baudrate);public native void close();static {Log.i("chw", "SerialPort ---> loadLibrary");System.loadLibrary("serial_port");}}

SerialPortFinder.java

/* * Copyright 2009 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.  */package android.serialport;import java.io.File;import java.io.FileReader;import java.io.IOException;import java.io.LineNumberReader;import java.util.Iterator;import java.util.Vector;import android.util.Log;public class SerialPortFinder {public class Driver {public Driver(String name, String root) {Log.i("chw", "SerialPortFinder ---> Driver");mDriverName = name;mDeviceRoot = root;}private String mDriverName;private String mDeviceRoot;Vector<File> mDevices = null;public Vector<File> getDevices() {Log.i("chw", "SerialPortFinder ---> getDevices");if (mDevices == null) {mDevices = new Vector<File>();File dev = new File("/dev");File[] files = dev.listFiles();int i;for (i=0; i<files.length; i++) {if (files[i].getAbsolutePath().startsWith(mDeviceRoot)) {Log.d(TAG, "Found new device: " + files[i]);mDevices.add(files[i]);}}}return mDevices;}public String getName() {Log.i("chw", "SerialPortFinder ---> getName");return mDriverName;}}private static final String TAG = "SerialPort";private Vector<Driver> mDrivers = null;Vector<Driver> getDrivers() throws IOException {Log.i("chw", "SerialPortFinder ---> getDrivers");if (mDrivers == null) {mDrivers = new Vector<Driver>();LineNumberReader r = new LineNumberReader(new FileReader("/proc/tty/drivers"));String l;while((l = r.readLine()) != null) {String[] w = l.split(" +");if ((w.length == 5) && (w[4].equals("serial"))) {Log.d(TAG, "Found new driver: " + w[1]);mDrivers.add(new Driver(w[0], w[1]));}}r.close();}return mDrivers;}public String[] getAllDevices() {Log.i("chw", "SerialPortFinder ---> getAllDevices");Vector<String> devices = new Vector<String>();// Parse each driverIterator<Driver> itdriv;try {itdriv = getDrivers().iterator();while(itdriv.hasNext()) {Driver driver = itdriv.next();Iterator<File> itdev = driver.getDevices().iterator();while(itdev.hasNext()) {String device = itdev.next().getName();String value = String.format("%s (%s)", device, driver.getName());devices.add(value);}}} catch (IOException e) {e.printStackTrace();}return devices.toArray(new String[devices.size()]);}public String[] getAllDevicesPath() {Log.i("chw", "SerialPortFinder ---> getAllDevicesPath");Vector<String> devices = new Vector<String>();// Parse each driverIterator<Driver> itdriv;try {itdriv = getDrivers().iterator();while(itdriv.hasNext()) {Driver driver = itdriv.next();Iterator<File> itdev = driver.getDevices().iterator();while(itdev.hasNext()) {String device = itdev.next().getAbsolutePath();devices.add(device);}}} catch (IOException e) {e.printStackTrace();}return devices.toArray(new String[devices.size()]);}}

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