Android串口操作方法实例

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;
    }
   }
  }
 }
4.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
[code]
 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);
}

[/code]
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;
 }
}