Android 串口通讯-------android -serialport-api

最近一段时间公司接了个饮水机串口通信的项目，于是去百度、github查找一些资料

http://code.google.com/p/android-serialport-api/这是谷歌提供的demo，但无法运行，这就尴尬了

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串口的操作无非就是几步：

1.打开串口（及配置串口）

2.读串口；

3.写串口；

4.关闭串口。

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提到串口就不得不说JNI了,它使java可以直接调用C生成的库，为可在android中使用串口，通过配置生成一个c语言的动态链接库serial_port.so(自动命名成libserial_port.so），并把它放在了libs/aemeabi 里，其c源文件在JNI中，大家在下载了android-serialport-api的源代码后，将这两个文件夹copy到自己新建的工程中即可。生成.so文件请看JNI配置

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相关代码

1，加载动态库.so文件

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, int flags) throws SecurityException, IOException {

        /* 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 666 " + device.getAbsolutePath() + "\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();
            }
        }

        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);
    }

    // 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("serial_port");
    }
}

2.C文件

JNI有一定了解的人就会知道，在写c语言链接库时候，函数的命名是和调用它的类所在的包名相关的，一旦包名与链接库中函数的命名不相符，就不能调用链接库的函数。这里可以打开jni中的.c文件

/*
 * 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 <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <jni.h>
#include "com_cosin_serialport_SerialPort.h"
#include "android/log.h"
static const char *TAG="serial_port";
#define LOGI(fmt, args...) __android_log_print(ANDROID_LOG_INFO,  TAG, fmt, ##args)
#define LOGD(fmt, args...) __android_log_print(ANDROID_LOG_DEBUG, TAG, fmt, ##args)
#define LOGE(fmt, args...) __android_log_print(ANDROID_LOG_ERROR, TAG, fmt, ##args)

static speed_t getBaudrate(jint baudrate)
{
    switch(baudrate) {
    case 0: return B0;
    case 50: return B50;
    case 75: return B75;
    case 110: return B110;
    case 134: return B134;
    case 150: return B150;
    case 200: return B200;
    case 300: return B300;
    case 600: return B600;
    case 1200: return B1200;
    case 1800: return B1800;
    case 2400: return B2400;
    case 4800: return B4800;
    case 9600: return B9600;
    case 19200: return B19200;
    case 38400: return B38400;
    case 57600: return B57600;
    case 115200: return B115200;
    case 230400: return B230400;
    case 460800: return B460800;
    case 500000: return B500000;
    case 576000: return B576000;
    case 921600: return B921600;
    case 1000000: return B1000000;
    case 1152000: return B1152000;
    case 1500000: return B1500000;
    case 2000000: return B2000000;
    case 2500000: return B2500000;
    case 3000000: return B3000000;
    case 3500000: return B3500000;
    case 4000000: return B4000000;
    default: return -1;
    }
}

/*
 * Class:     android_serialport_SerialPort
 * Method:    open
 * Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor;
 */
JNIEXPORT jobject JNICALL Java_com_cosin_serialport_SerialPort_open
  (JNIEnv *env, jclass thiz, jstring path, jint baudrate, jint flags)
{
    int fd;
    speed_t speed;
    jobject mFileDescriptor;

    /* Check arguments */
    {
        speed = getBaudrate(baudrate);
        if (speed == -1) {
            /* TODO: throw an exception */

            return NULL;
        }
    }

    /* Opening device */
    {
        jboolean iscopy;
        const char *path_utf = (*env)->GetStringUTFChars(env, path, &iscopy);

        fd = open(path_utf, O_RDWR | flags);

        (*env)->ReleaseStringUTFChars(env, path, path_utf);
        if (fd == -1)
        {
            /* Throw an exception */
            /* TODO: throw an exception */
            return NULL;
        }
    }

    /* Configure device */
    {
        struct termios cfg;
        if (tcgetattr(fd, &cfg))
        {
            close(fd);
            /* TODO: throw an exception */
            return NULL;
        }

        cfmakeraw(&cfg);
        cfsetispeed(&cfg, speed);
        cfsetospeed(&cfg, speed);

        if (tcsetattr(fd, TCSANOW, &cfg))
        {

            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_com_cosin_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);

    close(descriptor);
}

3.操作串口

/**
 * 进行串口通讯
 */
public class SerialPortData {
    private long nowTimes;
    public DeviceCodeCallBack mDeviceCodeCallBack = null;
    public CmdCallBack mCmdCallBack = null;
    public Timer mTimer = null;
    private static SerialPortData mSerial = null;
    private FileOutputStream fileOutputStream;
    private FileInputStream fileInputStream;
    private SerialPort serialPort;
    private int size;
    private SerialPortFinder finder;
    private byte[] buffer;
    private ReadThread readThread;
    private int i = 1;
    private Context Cotext;

    public static SerialPortData getIntence() {
        if (mSerial == null) {
            mSerial = new SerialPortData();
        }
        return mSerial;
    }

    /**
     * 打开串口
     */
    public void openSerialPort(Context mCotext) {

        Cotext = mCotext;
        try {
            serialPort = new SerialPort(new File("/dev/ttyS1"), Constant.BAUD_RATE, 0);
            fileOutputStream = (FileOutputStream) serialPort.getOutputStream();
            fileInputStream = (FileInputStream) serialPort.getInputStream();


            Toast.makeText(mCotext, "打开成功", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private InputStreamReader inputStream;

    /**
     * 启动线程接收数据
     */
    public void readReceivedData() {
        Log.i("zy", "线程进行中" + fileInputStream.toString());
        if (fileInputStream == null) {
            return;
        }
        if (readThread == null) {
            readThread = new ReadThread();
            readThread.start();
        }
    }

    /**
     * 把获取到的数据转成十六进制后设置到TextView显示
     *
     * @param buffer
     * @param size
     */
    private void onDataReceived(final byte[] buffer, final int size) {

        byteArrayToHex(buffer, size).toUpperCase();
    }

    /**
     * byte数组转成十六进制
     *
     * @param buffer
     * @param size
     * @return
     */
    public String byteArrayToHex(byte[] buffer, int size) {
        StringBuilder strBuilder = new StringBuilder();
        if (fileInputStream != null) {

            inputStream = new InputStreamReader(fileInputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStream);
            try {
                String buff = bufferedReader.readLine();
                if (buff.contains("+")) {
                    /**
                     * 截取+后面的数据
                     */
                    String indexString = buff.substring(buff.indexOf("+") + 1);
                    Log.i("zy", "截取数据-----" + indexString);
                    isData(indexString);
                }

            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return strBuilder.toString();
    }

    /**
     * 获取所有的串口设备
     */
    public void getAllSerialPortDevices() {
        finder = new SerialPortFinder();
        String[] devices = finder.getAllDevices();
        String[] paths = finder.getAllDevicesPath();
    }

    /**
     * 接收串口数据的线程；因为串口设备每秒发一次数据，这里一直接收。
     */
    class ReadThread extends Thread {
        @Override
        public void run() {
            while (true) {
                try {
                    buffer = new byte[512];
                    size = fileInputStream.read(buffer);
                    if (size > 0) {
                        onDataReceived(buffer, size);
                    }

                    Thread.sleep(1000);
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }
        }
    }

    /**
     * 输出字符串转字节
     */

    public void OutStreamDevices(final String sendOrder) {

        try {
            if (fileOutputStream == null) {
                return;
            }
            byte[] text = (sendOrder).getBytes();
            fileOutputStream.write(text);
            fileOutputStream.flush();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

以上就是我所有的操作。如果有问题，请联系本人，因没有直接在项目中实现，无法上传Demo,请见谅