android开发(37) android使用android_serialport_api 操作串口，解决权限问题

最近有个项目，要使用android设备操作串口的 斑马GK888T打印机，使用打印机打印二维码。

硬件设备连接方式：

安卓设备 通过 串口RS232 连接 斑马打印机的串口

那么就要解决：使用安卓设备操作串口的问题。 我找到一个框架：android_serialport_api，这个框架被托管在：

https://code.google.com/p/android-serialport-api/    谷歌的代码库，无奈国内无法下载

https://github.com/cepr/android-serialport-api     GITHUB的地址，这个可以下载

下载后，阅读下源代码，准备使用。

1.拷贝 jni 文件夹下的文件到 你的project中, 这些是jni调用的设定文件，包括:

　　Android.mk

　　Application.mk

　　gen_SerialPort_h.sh

　　SerialPort.c

　　SerialPort.h

2.拷贝libs 下的文件到你的 project中，这些是原生库，包括

　　armeabi/libserial_port.so

　　armeabi-v7a/libserial_port.so

　　x86/libserial_port.so

3.在你的项目下新建 package: android_serialport_api，拷贝下列src下的class  到这个package下

　　Application.java

　　SerialPort.java

　　SerialPortActivity.java

　　SerialPortFinder.java

　　注意， package名称一定要是android_serialport_api。或者你需要修改Android.mk下对应的模块配置项。不然会提示找不到jni调用的库

4.拷贝资源文件等：

　　string.xml 的内容：

    <string name="error_configuration">Please configure your serial port first.</string>
    <string name="error_security">You do not have read/write permission to the serial
        port.</string>
    <string name="error_unknown">The serial port can not be opened for an unknown
        reason.</string>

5.修改AndroidManifest.xml，在application节点指定对应的 "android:name" 配置，如下面红色文字所示

    <application
        android:allowBackup="true"
        android:name="android_serialport_api.Application"
        android:theme="@style/AppTheme" >

6.下面写测试的activity。我的设备连接在安卓设备的端口 ”ttyS2”上，下面是个演示：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:keepScreenOn="true"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/EditTextReception"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_weight="7"
        android:gravity="top"
        android:hint="Reception"
        android:isScrollContainer="true"
        android:scrollbarStyle="insideOverlay" >
    </EditText>

    <EditText
        android:id="@+id/EditTextEmission"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="Emission"
        android:lines="4"
        android:text="" >
    </EditText>

    <Button
        android:id="@+id/btnSend"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Send" />

</LinearLayout>

/*
 * 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 zyf.serialportdemo;

import java.io.IOException;

import zyf.serialportdemo.R;

import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.TextView.OnEditorActionListener;
import android_serialport_api.SerialPortActivity;

public class ConsoleActivity extends SerialPortActivity {
    Button btnSend;
    EditText mReception;
    EditText mEmission;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.console);

//        setTitle("Loopback test");
        mReception = (EditText) findViewById(R.id.EditTextReception);

        mEmission = (EditText) findViewById(R.id.EditTextEmission);

        btnSend = (Button)findViewById(R.id.btnSend);
        btnSend.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                String text = mEmission.getText().toString();
                try {
                    mOutputStream.write(new String(text).getBytes());
                    mOutputStream.write(‘\n‘);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
        //发送指令到斑马打印机
        mEmission.setText("^XA^A0N,40,30^FO50,150^FDHELLO WORLD^FS^XZ");　　　　/*二维码指令

　　　　　　^XA
　　　　　　^PMY
　　　　　　^FO200,200^BQ,2,10
　　　　　　^FDD03040C,LA,012345678912AABBqrcode^FS
　　　　　　^XZ

　　　　*/
    }

    @Override
    protected void onDataReceived(final byte[] buffer, final int size) {
        runOnUiThread(new Runnable() {
            public void run() {
                if (mReception != null) {
                    mReception.append(new String(buffer, 0, size));
                }
            }
        });
    }
}

/*
 * 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;

import java.io.File;
import java.io.IOException;
import java.security.InvalidParameterException;

import android.content.SharedPreferences;

public class Application extends android.app.Application {

    public SerialPortFinder mSerialPortFinder = new SerialPortFinder();
    private SerialPort mSerialPort = null;

    public SerialPort getSerialPort() throws SecurityException, IOException, InvalidParameterException {
        if (mSerialPort == null) {
            /* Read serial port parameters */
            //SharedPreferences sp = getSharedPreferences("android_serialport_api.sample_preferences", MODE_PRIVATE);
            //String path = sp.getString("DEVICE", "");
            //String path = "ttyS2";
            String path = "/dev/ttyS2";//指定端口
            //int baudrate = Integer.decode(sp.getString("BAUDRATE", "-1"));
            int baudrate = 9600;//指定速率
            /* Check parameters */
            if ( (path.length() == 0) || (baudrate == -1)) {
                throw new InvalidParameterException();
            }

            /* Open the serial port */
            mSerialPort = new SerialPort(new File(path), baudrate, 0);
        }
        return mSerialPort;
    }

    public void closeSerialPort() {
        if (mSerialPort != null) {
            mSerialPort.close();
            mSerialPort = null;
        }
    }
}

最后别忘了一个操作权限的问题，很多设备直接操作串口，会提示无权限 read/write 的问题，需要java层去提权，方法如下：

使用下面的方法执行指令： chmod 777 /dev/ttyS2

public void exeShell(String cmd){        

            try{
                 Process p = Runtime.getRuntime().exec(cmd);
                 BufferedReader in = new BufferedReader(
                                     new InputStreamReader(
                               p.getInputStream()));
                 String line = null;
                 while ((line = in.readLine()) != null) {
                    Log.i("exeShell",line);
                 }  

            }
            catch(Throwable t)
             {
                  t.printStackTrace();
                 }
        }

手动解决方法：打开cmd，进入  adb shell，执行：chmod 777 /dev/ttyS2

参考：

https://code.google.com/p/android-serialport-api/

https://github.com/cepr/android-serialport-api

http://blog.csdn.net/imyang2007/article/details/8331800

http://blog.csdn.net/imyang2007/article/details/8331800

http://bbs.csdn.net/topics/380234030