android 串口编程

import java.io.File;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import android.util.Log;

public class SerialPort {

 private static final String TAG = "SerialProt";

 private FileDescriptor mFd = null;    //--文件描述符
 private FileInputStream fis = null;    //--串口输入流
 private FileOutputStream fos = null;   //--串口输出流

 public SerialPort(File device, int baudrate, int flags)
   throws InterruptedException {
  /****** 判断文件是否可读可写 *******/
  if (!device.canRead() || !device.canRead()) {
   try {
    Process su;
    su = Runtime.getRuntime().exec("/System/xbin/su");
    String cmd = "chmod 777" + device.getAbsolutePath() + "\n" 
      + "exit\n";
    su.getOutputStream().write(cmd.getBytes());    //--更改权限可读可写
    if (su.waitFor() != 0 || !device.canRead()
      || !device.canWrite()) { // --更改权限后在判断，如果不能读写则抛出新异常
     throw new SecurityException();
    }
   } catch (IOException e) {
    e.printStackTrace();
    throw new SecurityException();
   }
  }
  mFd = open(device.getAbsolutePath(), baudrate, flags);
  if (mFd == null) {
   Log.d(TAG, "native open returns null");
  }

  fis = new FileInputStream(mFd);
  fos = new FileOutputStream(mFd);
 }

 public FileInputStream getFis() {
  return fis;
 }

 public FileOutputStream getFos() {
  return fos;
 }

 // --JNI
 private native static FileDescriptor open(String path, int baudrate, int flags);   //--打开串口本地方法
 public native void close();  //--关闭串口本地方法
 static {
  System.loadLibrary("serial_port");
 }
}