android 串口 android-serialport-api

最近在做Android串口的开发，找到一个开源的串口类android-serialport-api。其主页在这里http://code.google.com/p/android-serialport-api/  ，这里可以下到APK及对源码。

但是下载源码之后发现源码不能直接使用，而且源码结构较为复杂。关于串口的操作不外乎几步：

1.打开串口（及配置串口）；

2.读串口；

3.写串口；

4.关闭串口。

android-serialport-api的代码使用了继承等复杂的行为，不容易使初学者很快掌握关于串口的上述4步，所以我特别自己写了一个demo，只有一个activity，其中包含了打开串口，写串口，读串口的操作，对于关闭串口，大家一开就会不明白怎么写了。

http://www.cnblogs.com/CZM-/p/7943572.html

参考此贴，利用NDK编译jni c文件为库并运行

这里是工程结构

首先新建jni包，添加SerialPort.c即可，

/*
 * 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 "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 : return B0;
    case : return B50;
    case : return B75;
    case : return B110;
    case : return B134;
    case : return B150;
    case : return B200;
    case : return B300;
    case : return B600;
    case : return B1200;
    case : return B1800;
    case : return B2400;
    case : return B4800;
    case : return B9600;
    case : return B19200;
    case : return B38400;
    case : return B57600;
    case : return B115200;
    case : return B230400;
    case : return B460800;
    case : return B500000;
    case : return B576000;
    case : return B921600;
    case : return B1000000;
    case : return B1152000;
    case : return B1500000;
    case : return B2000000;
    case : return B2500000;
    case : return B3000000;
    case : return B3500000;
    case : return B4000000;
    default: return -;
    }
}

/*
 * Class:     android_serialport_SerialPort
 * Method:    open
 * Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor;
 */
JNIEXPORT jobject JNICALL Java_android_1serialport_1api_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 == -) {
            /* 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 with flags 0x%x", path_utf, O_RDWR | flags);
        fd = open(path_utf, O_RDWR | flags);
//        LOGD("open() fd = %d", fd);
        (*env)->ReleaseStringUTFChars(env, path, path_utf);
        if (fd == -)
        {
            /* 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_1serialport_1api_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);
}

接下来在工程的local.properties文件中添加NDK路径（上面下载好的那个NDK），类似其中的SDK路径一样，我的添加后如下：

ndk.dir=/home/cam/Android/Sdk/ndk-bundle
sdk.dir=/home/cam/Android/Sdk

接下来在app module目录下的build.gradle中设置库文件名（生成的so文件名）。找到gradle文件的defaultConfig这项，在里面添加如下内容：

    defaultConfig {

        ndk {
            moduleName "testhello"
            ldLibs "log", "z", "m"  //添加依赖库文件，因为有log打印等
        }
    }

新建android_serialport_api包，(包名字必须一模一样，不然需要根据你的包名重新编译产生头文件，并修改c文件)并在此包下新建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_api;

import android.util.Log;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;
import java.util.Iterator;
import java.util.Vector;

public class SerialPortFinder {

    public class Driver {
        private String mDriverName;
        private String mDeviceRoot;
        Vector<File> mDevices = null;
        public Driver(String name, String root) {
            mDriverName = name;
            mDeviceRoot = root;
        }
        public Vector<File> getDevices() {
            if (mDevices == null) {
                mDevices = new Vector<File>();
                File dev = new File("/dev");
                File[] files = dev.listFiles();
                if(null == files || files.length ==0){
                    return mDevices;
                }
                int i;
                for (i=0; i<files.length; i++) {
                    if (files[i].getAbsolutePath().startsWith(mDeviceRoot)) {
                        Log.d(TAG, "查找的设备: " + files[i]);
                        mDevices.add(files[i]);
                    }
                }
            }
            return mDevices;
        }
        public String getName() {
            return mDriverName;
        }
    }

    private static final String TAG = "SerialPort";

    private Vector<Driver> mDrivers = null;

    Vector<Driver> getDrivers() throws IOException {
        if (mDrivers == null) {
            mDrivers = new Vector<Driver>();
            LineNumberReader r = new LineNumberReader(new FileReader("/proc/tty/drivers"));
            String l;
            while((l = r.readLine()) != null) {
                String drivername = l.substring(0, 0x15).trim();
                String[] w = l.split(" +");
                if ((w.length >= 5) && (w[w.length-1].equals("serial"))) {
                    Log.d(TAG, "---串口设备=" + drivername + " on " + w[w.length-4]);
                    mDrivers.add(new Driver(drivername, w[w.length-4]));
                }
            }
            r.close();
        }
        return mDrivers;
    }

    public String[] getAllDevices() {
        Vector<String> devices = new Vector<String>();
        // Parse each driver
        Iterator<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() {
        Vector<String> devices = new Vector<String>();
        Iterator<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()]);
    }
}

创建主活动MainActivity.java

package com.otherway.myapplication;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android_serialport_api.SerialPort;

public class MainActivity extends Activity implements View.OnClickListener {
    private static final String TAG = "MainActivity";

    protected SerialPort mSerialPort;
    protected InputStream mInputStream;
    protected OutputStream mOutputStream;

    private String prot = "/dev/ttySAC2";
    private int baudrate = 9600;
    private static long i = 0;

    private Toast mToast;

    Handler handler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            if (msg.what == 1) {

            }
        }
    };
    private Thread receiveThread;
    private Thread sendThread;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initLayout();

        mToast = Toast.makeText(this, "", Toast.LENGTH_SHORT);
    }

    /**
     * 初始化Layout。
     */
    private void initLayout() {
        findViewById(R.id.btn_open).setOnClickListener(MainActivity.this);
        findViewById(R.id.btn_send).setOnClickListener(MainActivity.this);
        findViewById(R.id.btn_close).setOnClickListener(MainActivity.this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn_open:
                showTip("btn_open");

                // 打开
                try {
                    mSerialPort = new SerialPort(new File(prot), baudrate, 0);
                    mInputStream = mSerialPort.getInputStream();
                    mOutputStream = mSerialPort.getOutputStream();
                    receiveThread();
                } catch (SecurityException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    Log.e(TAG, "打开失败");
                    e.printStackTrace();
                }

                break;
            case R.id.btn_send:
                showTip("btn_send");

                // 发送
                sendThread = new Thread() {
                    @Override
                    public void run() {
                        while (true) {
                            try {
                                i++;
                                mOutputStream.write((String.valueOf(i)).getBytes());
                                Log.i("test", "发送成功:1" + i);
                                Thread.sleep(1);
                            } catch (Exception e) {
                                Log.i("test", "发送失败");
                                e.printStackTrace();
                            }
                        }
                    }
                };
                sendThread.start();

                break;
            case R.id.btn_close:
                showTip("btn_close");

                closeSerialPort();

                break;
            default:
                break;
        }
    }

    private void receiveThread() {
        // 接收
        receiveThread = new Thread() {
            @Override
            public void run() {
                while (true) {
                    int size;
                    try {
                        byte[] buffer = new byte[1024];
                        if (mInputStream == null)
                            return;
                        size = mInputStream.read(buffer);
                        if (size > 0) {
                            String recinfo = new String(buffer, 0,
                                    size);
                            Log.i("test", "接收到串口信息:" + recinfo);
//                            sb = recinfo;
//                            handler.sendEmptyMessage(1);
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        receiveThread.start();
    }

    /**
     * 关闭串口
     */
    public void closeSerialPort() {

        if (mSerialPort != null) {
            mSerialPort.close();
        }
        if (mInputStream != null) {
            try {
                mInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (mOutputStream != null) {
            try {
                mOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

    private void showTip(final String str) {
        mToast.setText(str);
        mToast.show();
    }
}

主界面布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.otherway.myapplication.MainActivity">

    <Button
        android:id="@+id/btn_open"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="100dp"
        android:text="打开" />

    <Button
        android:id="@+id/btn_send"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/btn_open"
        android:text="发送" />

    <Button
        android:id="@+id/btn_close"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/btn_send"
        android:text="关闭" />

</RelativeLayout>

改为你需要的串口端口号及波特率；

测试时将串口rx，tx短接，打开串口后，再点击发送程序会一直循环发送，在调试信息上会打印出串口接受数据；