android串口操作

1.首先下载一个libserial_port.so，新建目录libs/armeabi,将so文件放到该目录下。
2.定义串口类，在类的构建函数中修改权限，打开设备，创建输入流和输出流，通过native接口访问串口打开关闭函数
public class SerialPort {
 /*Do not remove or rename the field mFd: it is used by native method close();*/
 public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException, InvalidParameterException{
//如果串口权限不够，改变权限
  /* 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);//打开串口
  if (mFd == null) {
   Log.e(TAG, "native open returns null");
   throw new IOException();
  }
  mFileInputStream = new FileInputStream(mFd);//串口输入流
  mFileOutputStream = new FileOutputStream(mFd);//串口输出流
 }
 // 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);//c文件中的串口open()函数
 public native void close();//c文件中的串口close()函数
 static {
  System.loadLibrary("serial_port");//加载串口库
 }
}
}
3.定义抽象类ServerData,
public abstract class ServerData {
 protected SerialPort mSerialPort;
 protected OutputStream mOutputStream;
 private InputStream mInputStream;
 private ReadThread mReadThread;
 private class ReadThread extends Thread {
  @Override
  //在线程中读取数据并处理数据
  public void run() {
   super.run();
   byte[] buffer = new byte[128];
   int size;
   while(true) {
    try {
     if (mInputStream == null) return;
     size = mInputStream.read(buffer);//读取数据
     if (size > 0) {
      onDataReceived(buffer, size);//处理数据
     }
    } catch (IOException e) {
     e.printStackTrace();
     return;
    }
   }
  }
 }
 //实例化串口类，输出流和输入流，实例化读取线程并开始执行该线程
 public ServerData(String path, int baudrate){
  try {
   mSerialPort = new SerialPort(new File(path), baudrate, 0); 
   mOutputStream = mSerialPort.getOutputStream();
   mInputStream = mSerialPort.getInputStream();
   /* Create a receiving thread */
   mReadThread = new ReadThread();
   mReadThread.start();
  } catch (SecurityException e) {
  } catch (IOException e) {
  } catch (InvalidParameterException e) {
  }
 }
 protected abstract void onDataReceived(final byte[] buffer, final int size);
}
5.然后再新建一个类，在新建的类中实现上面的抽象函数，并写一个函数返回读取到的数据。

package View;
//导入R类，所在包不同，不能直接饮用，需要导入才可以使用
import android_serialport_api.sample.R;
/* EtcView类，Etc界面管理 */
public class SerialView {
 private Activity context = null;
 private Serial mEtcServer = null;
 /* Etc界面构造函数 */
 public SerialView(Activity context) {
  this.context = context;
 }
 public void EtcInitView() {
  //这样才可以找到android_serialport_api.sample包下的id
  TextView mytext=(TextView)context.findViewById(R.id.mytext);
  mEtcServer = new Serial("/dev/s3c2410_serial3", 9600);
 }
 public void EtcRefresh() {
  //返回串口线程读取的数据
  byte[] buffer = mEtcServer.getdata();
  String recString=new String(buffer);//将byte[]的数组转换成字符串string
  mytext.setText(recString);//设置字符文本
  buffer = null;
 }
}