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

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

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