Android串口通信

1. 解析SerialPort API 串口通信例子

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首先分析一下例子中的类结构：

Android串口通信

通过类结构可知，最主要的还是在SerialPortJNI.java 类，该类写了一些Native 方法处理打开与关闭串口接收发送的

SerialPort.Java 代码如下：

package com.dwin.navy.serialportapi;

import java.io.FileDescriptor;

import android.util.Log;

/**

* 串口JNI

* @author dwin

public class SerialPortJNI {

static {

Log.i("NativeClass", "before load library");

System.loadLibrary("serialport");

Log.i("NativeClass", "after load library");

}

public FileDescriptor mFd;

public String mDevNum;

public int mSpeed;

public int mDataBits;

public int mStopBits;

public int mParity;

public int RS485ModFp = -1;

public static int RS485Read = 0;

public static int RS485Write = 1;

public native int setSpeed(FileDescriptor fd, int speed);

public native int setParity(FileDescriptor fd, int dataBits, int stopBits,

int parity);

public native FileDescriptor openDev(String devNum);

public native FileDescriptor open485Dev(String devNum);

public native int closeDev(FileDescriptor fd);

public native int close485Dev(FileDescriptor fd);

public native int readBytes(FileDescriptor fd, byte[] buffer, int length);

public native boolean writeBytes(FileDescriptor fd, byte[] buffer,

int length);

public native int set485mod(int mode);

}

红色区域先申明一个static 静态域加载.so 动态库文件 .so通过JNI方式生成保存在libs目录下，由于本例子使用的cpu为 mips（默认为arm）所以 .so库文件将存入mips文件夹下

还有打开串口，关闭串口，485模式下开关方式，接收与发送 byte

1> SerialPort API 处理了接收与发送文本与十六进制两种模式下接收与发送数据

UI布局如下：

Android串口通信

2>在电脑中插入usb转串口工具，然后在app中打开串口

SerialPortOpt.java 继承了 SerialPortJNI.Java 类调用相应的JNI接口

SerialPortOpt.java 类大致如下 :

package com.dwin.navy.serialportapi;

import java.io.FileDescriptor;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.OutputStream;

import android.util.Log;

/**

* 调用JNI的串口

* @author dwin

public class SerailPortOpt extends SerialPortJNI {

private static final String TAG = "SerialPort";

private FileInputStream mFileInputStream;

private FileOutputStream mFileOutputStream;

public FileDescriptor openDev(String devNum) {

super.mFd = super.openDev(devNum);

if (super.mFd == null) {

Log.e(TAG, "native open returns null");

return null;

}

mFileInputStream = new FileInputStream(super.mFd);

mFileOutputStream = new FileOutputStream(super.mFd);

return super.mFd;

}

public FileDescriptor open485Dev(String devNum) {

super.mFd = super.open485Dev(devNum);

if (super.mFd == null) {

Log.e(TAG, "native open returns null");

return null;

}

mFileInputStream = new FileInputStream(super.mFd);

mFileOutputStream = new FileOutputStream(super.mFd);

return super.mFd;

}

public InputStream getInputStream() {

return mFileInputStream;

}

public OutputStream getOutputStream() {

return mFileOutputStream;

}

public int setSpeed(FileDescriptor optFd, int speed) {

return super.setSpeed(optFd, speed);

}

public int setParity(FileDescriptor optFd, int databits, int stopbits,

int parity) {

return super.setParity(optFd, databits, stopbits, parity);

}

public int closeDev(FileDescriptor optFd) {

int retStatus;

retStatus = super.closeDev(optFd);

super.mFd = null;

return retStatus;

}

public int close485Dev(FileDescriptor optFd) {

int retStatus;

retStatus = super.close485Dev(optFd);

super.mFd = null;

return retStatus;

}

public int readBytes(FileDescriptor fd, byte[] buffer, int length) {

return super.readBytes(fd, buffer, length);

}

public boolean writeBytes(FileDescriptor fd, byte[] buffer, int length) {

return super.writeBytes(fd, buffer, length);

}

public int readBytes(FileDescriptor fd, byte[] buffer) {

return super.readBytes(fd, buffer, buffer.length);

}

public boolean writeBytes(FileDescriptor fd, byte[] buffer) {

return super.writeBytes(fd, buffer, buffer.length);

}

public int readBytes(byte[] buffer) {

return super.readBytes(mFd, buffer, buffer.length);

}

public boolean writeBytes(byte[] buffer) {

return super.writeBytes(mFd, buffer, buffer.length);

}

public int read485Bytes(FileDescriptor fd, byte[] buffer, int length) {

return super.readBytes(fd, buffer, length);

}

public boolean write485Bytes(FileDescriptor fd, byte[] buffer, int length) {

boolean ret;

super.set485mod(RS485Write);

ret = super.writeBytes(fd, buffer, length);

super.set485mod(RS485Read);

return ret;

}

public int read485Bytes(FileDescriptor fd, byte[] buffer) {

return super.readBytes(fd, buffer, buffer.length);

}

public boolean write485Bytes(FileDescriptor fd, byte[] buffer) {

boolean ret;

super.set485mod(RS485Write);

ret = super.writeBytes(fd, buffer, buffer.length);

super.set485mod(RS485Read);

return ret;

}

public int read485Bytes(byte[] buffer) {

return super.readBytes(mFd, buffer, buffer.length);

}

public boolean write485Bytes(byte[] buffer) {

boolean ret;

super.set485mod(RS485Write);

ret = super.writeBytes(mFd, buffer, buffer.length);

super.set485mod(RS485Read);

return ret;

}

在openDev（String str）方法中调用父类的方法，将返回一个文件描述对象FileDescriptor ，然后初始化 FileInputStream，FileOutputStream 输入输出IO流对象，

还有读写byte字节数组的方法

3>申明或者实例化一个类用来调用和实现这些方法前两个类只是申明相应的方法并没有实现相应的方法体

定义一个SerialPort 类

SerialPort.Java ：

package com.dwin.dwinapi;

import java.io.FileDescriptor;

import java.io.IOException;

import java.io.InputStream;

import java.io.UnsupportedEncodingException;

import com.dwin.navy.serialportapi.SerailPortOpt;

import android.content.Context;

import android.util.Log;

/**

* 自定义串口对象

* @author F

public class SerialPort {

Context context;

/**

* 自定义串口对象

private static SerialPort serialPort;

/**

* 调用JNI的串口

private SerailPortOpt serialportopt;

/**

* 读取数据线程

/**

* 串口接收到的流

private InputStream mInputStream;

/**

* 用来判断串口是否已打开

public boolean isOpen = false;

* 接收到的数据

String data;

/**

* 实例化并打开串口对象

* @param devNum

* 串口号 S0，S1，S2，S3,S4

* @param dataBits

* 数据位

* @param speed

* 波特率

* @param stopBits

* 停止位

* @param parity

* 校验位

public SerialPort(String devNum, int speed, int dataBits, int stopBits,

int parity) {

serialportopt = new SerailPortOpt();

openSerial(devNum, speed, dataBits, stopBits, parity);

}

/**

* 打开串口时传入参数，可以指定打开某个串口，并设置相应的参数

* @param devNum

* 串口号 COM0，COM1，COM2，COM3,COM4

* @param dataBits

* 数据位

* @param speed

* 波特率

* @param stopBits

* 停止位

* @param parity

* 校验位

* @return

private boolean openSerial(String devNum, int speed, int dataBits,

int stopBits, int parity) {

serialportopt.mDevNum = devNum;

serialportopt.mDataBits = dataBits;

serialportopt.mSpeed = speed;

serialportopt.mStopBits = stopBits;

serialportopt.mParity = parity;

// 打开串口

FileDescriptor fd = serialportopt.openDev(serialportopt.mDevNum);

if (fd == null) {

return false;// 串口打开失败

} else {

// 设置串口参数

serialportopt.setSpeed(fd, speed);

serialportopt.setParity(fd, dataBits, stopBits, parity);

mInputStream = serialportopt.getInputStream();

isOpen = true;

return true;

}

/**

* 关闭串口

public void closeSerial() {

if (serialportopt.mFd != null) {

serialportopt.closeDev(serialportopt.mFd);

isOpen = false;

}

/**

* 发送数据

* @param data

* 数据内容

public void sendData(String data, String type) {

try {

serialportopt.writeBytes(type.equals("HEX") ? HexString2Bytes(data

.length() % 2 == 1 ? data += "0" : data.replace(" ", ""))

: HexString2Bytes(toHexString(data)));

} catch (Exception e) {

}

/**

* 接收数据

* @param 收发数据类型

* @return 接收到的字符串

public String receiveData(String type) {

byte[] buf = new byte[1024];

int size;

if (mInputStream == null) {

return null;

}

size = serialportopt.readBytes(buf);

if (size > 0) {

try {

data = type.equals("HEX") ? bytesToHexString(buf, size)

: new String(buf, 0, size, "gb2312").trim().toString();

} catch (UnsupportedEncodingException e) {

e.printStackTrace();

}

return data;

} else {

return null;

}

/**

* 转化字符串为十六进制编码

* @param s

* @return

private String toHexString(String s) {

String str = "";

for (int i = 0; i < s.length(); i++) {

int ch = (int) s.charAt(i);

String s4 = Integer.toHexString(ch);

str = str + s4;

}

return str;

}

/**

* 将指定字符串src，以每两个字符分割转换为16进制形式如："2B44EFD9" --> byte[]{0x2B, 0x44, 0xEF,

* 0xD9}

* @param src

* String

* @return byte[]

private static byte[] HexString2Bytes(String src) {

byte[] ret = new byte[src.length() / 2];

byte[] tmp = src.getBytes();

for (int i = 0; i < tmp.length / 2; i++) {

ret[i] = uniteBytes(tmp[i * 2], tmp[i * 2 + 1]);

}

return ret;

}

/**

* 将Hex数组转换为Hex字符串

* @param src

* @param size

* @return

public static String bytesToHexString(byte[] src, int size) {

String ret = "";

if (src == null || size <= 0) {

return null;

}

for (int i = 0; i < size; i++) {

String hex = Integer.toHexString(src[i] & 0xFF);

if (hex.length() < 2) {

hex = "0" + hex;

}

hex += " ";

ret += hex;

}

return ret.toUpperCase();

}

/**

* 将两个ASCII字符合成一个字节；如："EF"--> 0xEF

* @param src0

* byte

* @param src1

* byte

* @return byte

private static byte uniteBytes(byte src0, byte src1) {

byte _b0 = Byte.decode("0x" + new String(new byte[] { src0 }))

.byteValue();

_b0 = (byte) (_b0 << 4);

byte _b1 = Byte.decode("0x" + new String(new byte[] { src1 }))

.byteValue();

byte ret = (byte) (_b0 ^ _b1);

return ret;

}

剩下的就是MainActivty中，打开串口创建两个线程，ReceiverThread，SendThread 先，Handler 异步更新UI

private Handler mHandler = new Handler() {

public void handleMessage(android.os.Message msg) {

switch (msg.what) {

case 1:

Date date = new Date();

eTextShowMsg.append("[" + date.getMinutes() + ":"

+ date.getSeconds() + "] " + (CharSequence) msg.obj);

break;

default:

break;

}

};

/**

* 接收数据线程

class ReceiveThread extends Thread {

public void run() {

while (serialPort.isOpen) {

if (isReceive) {

String type = togBtnShowDataType.getText().toString()

.trim();

String data = serialPort.receiveData(type);

if (data != null) {

Message msg = new Message();

msg.what = 1;

msg.obj = data;

System.out.println(data + "<<<<<<<<==========data");

mHandler.sendMessage(msg);

}

try {

Thread.sleep(1000);

} catch (InterruptedException e) {

e.printStackTrace();

}

当串口接收到数据每一秒更新一次UI，根据需求可转换为十六进制与字符

文章名称：Android串口通信
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Android串口通信

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