模擬器與虛擬串口之間的通信

• Eclipse + ADT
• 模擬器版本：Andoid 4.4.2：該版本 不需要root操作：注意：不是第三方模擬器
  
• 串口助手與模擬器之間的串口通信的步驟：

（1）第一步 ：創建虛擬串口

（2）第二步 ：模擬器掛載虛擬串口并啟動模擬器：在cmd小黑屏下輸入

emulator -avd dcom -writable-system -qemu -serial COM2
> emulator：emulator.exe程序在\android-sdk-windows\tools目錄下
> dcom：模擬器名稱
> COM2：串口號
完整格式： emulator -avd 模擬器名稱 -writable-system -qemu -serial 串口號
=======================================================================
查看模擬器列表命令：emulator -list-avds

（3）第三步 ：在Android模擬器上安裝一個串口調試工具：adb instanll ApkPath

（4）第四步 ：測試串口助手與模擬器之間串口通信

Android串口API編程

• 第一步：上網down一個Android串口開發包：android-serialport-api-master是Android串口開源類
  
• 第二步：創建Android工程
  
• 第三步：導包：將Android開發包android-serialport-api中的jni目錄與libs目錄下的文件拷貝到當前工程中
  
• 第四步： 拷貝兩個核心類到當前工程中：
  
  
• 第五步： 測試打開串口是否能夠成功并寫串口寫入數據
  

完整Android串口代碼Demo

• 布局文件

<LinearLayout 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:orientation="vertical"
    tools:context="${relativePackage}.${activityClass}" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="測試打卡串口并發送數據" />
    <Button 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="打開串口"
        android:onClick="onOpenSerialPort"/>
    <Button 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="發送數據[0x01, 0x02, 0x04, 0x08]"
        android:onClick="onSendData"/>
    <Button 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="關閉串口"
        android:onClick="onCloseSerialPort"/>

</LinearLayout>

• MainActivity代碼

package com.ycom.androidserialassistant;

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

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

public class MainActivity extends Activity {
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}
	
	private SerialPort port = null;
	private OutputStream os = null;
	private InputStream in = null;
	
	// 打開串口
	public void onOpenSerialPort(View v) {
		if (port == null) {
			String portName = "/dev/ttyS2";
			int baudrate = 9600;
			try {
				port = new SerialPort(new File(portName), baudrate, 0);
			} catch (Exception e) {
				Toast.makeText(this, "打開串口失敗", 0).show();
				return;
			} 
		}
		os = port.getOutputStream();
		in = port.getInputStream();
		
		// 開啟分線程來讀取串口中的數據
		new Thread() {
			public void run() {
				byte[] data = new byte[64];
				while (true) {
					try {
						int len = in.read(data);
						Log.i("MainActivity", "len = " + len);
						Log.i("MainActivity", Arrays.toString(data));
					} catch (IOException e) {
					}
				}
			}
		}.start();
		
		Toast.makeText(this, "打開串口成功", 0).show();
	}
	// 發送數據
	public void onSendData(View v) {
		if (port != null) {
			byte data[] = {0x01, 0x02, 0x04, 0x08};
			try {
				os.write(data);
				os.flush();
			} catch (IOException e) {
				
			}
		}
	}
	// 關閉串口
	public void onCloseSerialPort(View v) throws IOException {
		if (port != null) {
			os.close();
			in.close();
			port.close();
			port = null;
		}
	}
}

核心類SerialPort的完整代碼

/*
 * 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; // 包名不要修改☆☆☆☆☆

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

import android.util.Log;

public class SerialPort {

	private static final String TAG = "SerialPort";

	/*
	 * Do not remove or rename the field mFd: it is used by native method close();
	 */
	private FileDescriptor mFd;
	private FileInputStream mFileInputStream;
	private FileOutputStream mFileOutputStream;

	public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException {

		/* 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");
				// 注: 如果需要可以講chmod 666修改為chmod 777
				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);
		if (mFd == null) {
			Log.e(TAG, "native open returns null");
			throw new IOException();
		}
		mFileInputStream = new FileInputStream(mFd);
		mFileOutputStream = new FileOutputStream(mFd);
	}

	// Getters and setters: 獲取串口對象的輸入流對象
	// 用于從串口讀取數據
	public InputStream getInputStream() {
		return mFileInputStream;
	}

	// 獲取串口對象的輸出流對象
	// 用于向串口寫數據
	public OutputStream getOutputStream() {
		return mFileOutputStream;
	}

	// JNI
	private native static FileDescriptor open(String path, int baudrate, int flags);
	public native void close();
	static {
		System.loadLibrary("serial_port");
	}
}