android jni

以前做的BLE，现在做串口通信，说说自己的经验。

1、首先你要有串口通信代码 ，也就是C/C++的代码，网上有很多android_serialport_api，我也上传一个，方便使用，咦！~ 好像不行，没有办法了 ，只有你们自己下载了。

2、

添加 SerialPort 类

在网上找到 SerialPort 的 Java 类，添加到项目中。

package com.xd.serialport;

import android.util.Log;

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;

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");  
                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  
    public InputStream getInputStream() {  
        return mFileInputStream;  
    }  

    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");  
    }  
}

项目结构如下：

---

生成 c 语言头文件

• 打开 Terminal（View -> Tool Windows -> Terminal）

  

• 输入cd app\src\main\java进入源码所在目录

  

• 输入javah -jni com.xd.serialport.SerialPort生成头文件

  

  

---

创建 jni 文件夹，添加 .c 文件

• 右键 Moudle，右键菜单中选择 New -> Folder -> JNI Folder，弹出的对话框，直接点击完成。

  

• 将前面生成的 .h 文件移入 jni 文件夹中。

• 右键 jni 文件夹，右键菜单中选择New -> C/C++ Source File创建与 .h 文件同名的 .c 文件。

  

• 为 .c 文件添加如下内容（来源于网络）。

  注意：需要将include头文件、open、close方法中的包名修改为自己的包名。

  
  #include <com_xd_serialport_SerialPort.h>  
  
  
  #include <termios.h>  
  
  
  #include <unistd.h>  
  
  
  #include <sys/types.h>  
  
  
  #include <sys/stat.h>  
  
  
  #include <fcntl.h>  
  
  
  #include <string.h>  
  
  
  #include <jni.h>  
  
  
  
  #include "android/log.h"  
  
  static const char *TAG="serial_port";  
  
  #define LOGI(fmt, args...) __android_log_print(ANDROID_LOG_INFO, TAG, fmt, ##args)  
  
  
  #define LOGD(fmt, args...) __android_log_print(ANDROID_LOG_DEBUG, TAG, fmt, ##args)  
  
  
  #define LOGE(fmt, args...) __android_log_print(ANDROID_LOG_ERROR, TAG, fmt, ##args)  
  
  
  /* 
  * Class: android_serialport_SerialPort 
  * Method: open 
  * Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor; 
  */  
  static speed_t getBaudrate(jint baudrate)  
  {  
      switch(baudrate) {  
      case 0: return B0;  
      case 50: return B50;  
      case 75: return B75;  
      case 110: return B110;  
      case 134: return B134;  
      case 150: return B150;  
      case 200: return B200;  
      case 300: return B300;  
      case 600: return B600;  
      case 1200: return B1200;  
      case 1800: return B1800;  
      case 2400: return B2400;  
      case 4800: return B4800;  
      case 9600: return B9600;  
      case 19200: return B19200;  
      case 38400: return B38400;  
      case 57600: return B57600;  
      case 115200: return B115200;  
      case 230400: return B230400;  
      case 460800: return B460800;  
      case 500000: return B500000;  
      case 576000: return B576000;  
      case 921600: return B921600;  
      case 1000000: return B1000000;  
      case 1152000: return B1152000;  
      case 1500000: return B1500000;  
      case 2000000: return B2000000;  
      case 2500000: return B2500000;  
      case 3000000: return B3000000;  
      case 3500000: return B3500000;  
      case 4000000: return B4000000;  
      default: return -1;  
      }  
  }  
  
  /* 
   * Class:     android_serialport_SerialPort 
   * Method:    open 
   * Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor; 
   */  
  JNIEXPORT jobject JNICALL Java_com_xd_serialport_SerialPort_open  
    (JNIEnv *env, jclass thiz, jstring path, jint baudrate, jint flags)  
  {  
      int fd;  
      speed_t speed;  
      jobject mFileDescriptor;  
  
      /* Check arguments */  
      {  
          speed = getBaudrate(baudrate);  
          if (speed == -1) {  
              /* TODO: throw an exception */  
              LOGE("Invalid baudrate");  
              return NULL;  
          }  
      }  
  
      /* Opening device */  
      {  
          jboolean iscopy;  
          const char *path_utf = (*env)->GetStringUTFChars(env, path, &iscopy);  
          LOGD("Opening serial port %s with flags 0x%x", path_utf, O_RDWR | flags);  
          fd = open(path_utf, O_RDWR | flags);  
          LOGD("open() fd = %d", fd);  
          (*env)->ReleaseStringUTFChars(env, path, path_utf);  
          if (fd == -1)  
          {  
              /* Throw an exception */  
              LOGE("Cannot open port");  
              /* TODO: throw an exception */  
              return NULL;  
          }  
      }  
  
      /* Configure device */  
      {  
          struct termios cfg;  
          LOGD("Configuring serial port");  
          if (tcgetattr(fd, &cfg))  
          {  
              LOGE("tcgetattr() failed");  
              close(fd);  
              /* TODO: throw an exception */  
              return NULL;  
          }  
  
          cfmakeraw(&cfg);  
          cfsetispeed(&cfg, speed);  
          cfsetospeed(&cfg, speed);  
  
          if (tcsetattr(fd, TCSANOW, &cfg))  
          {  
              LOGE("tcsetattr() failed");  
              close(fd);  
              /* TODO: throw an exception */  
              return NULL;  
          }  
      }  
  
      /* Create a corresponding file descriptor */  
      {  
          jclass cFileDescriptor = (*env)->FindClass(env, "java/io/FileDescriptor");  
          jmethodID iFileDescriptor = (*env)->GetMethodID(env, cFileDescriptor, "<init>", "()V");  
          jfieldID descriptorID = (*env)->GetFieldID(env, cFileDescriptor, "descriptor", "I");  
          mFileDescriptor = (*env)->NewObject(env, cFileDescriptor, iFileDescriptor);  
          (*env)->SetIntField(env, mFileDescriptor, descriptorID, (jint)fd);  
      }  
  
      return mFileDescriptor;  
  }  
  
  /* 
   * Class:     cedric_serial_SerialPort 
   * Method:    close 
   * Signature: ()V 
   */  
  JNIEXPORT void JNICALL Java_com_xd_serialport_SerialPort_close  
    (JNIEnv *env, jobject thiz)  
  {  
      jclass SerialPortClass = (*env)->GetObjectClass(env, thiz);  
      jclass FileDescriptorClass = (*env)->FindClass(env, "java/io/FileDescriptor");  
  
      jfieldID mFdID = (*env)->GetFieldID(env, SerialPortClass, "mFd", "Ljava/io/FileDescriptor;");  
      jfieldID descriptorID = (*env)->GetFieldID(env, FileDescriptorClass, "descriptor", "I");  
  
      jobject mFd = (*env)->GetObjectField(env, thiz, mFdID);  
      jint descriptor = (*env)->GetIntField(env, mFd, descriptorID);  
  
      LOGD("close(fd = %d)", descriptor);  
      close(descriptor);  
  }

  

---

配置NDK，生成 .so 文件

• 在 local.properties 添加 ndk 路径

  

  Android-ndk的版本至少要 r9d 以上的版本，如果等于或低于该版本，运行时会提示No rule to make target的错误。我使用的是 r10e 的版本。

• 在 module 的 build.gradle 中添加 ndk 配置

  在 defaultConfig 节点下添加：

  ndk{  
      abiFilter "armeabi"  
      moduleName "serial_port"  // 生成so的名称
      ldLibs "log", "z", "m", "jnigraphics", "android"  
  }

• 在 gradle.properties 中添加android.useDeprecatedNdk=true，否则 sync 时会提示错误NDK integration is deprecated in the current plugin.

• Sync Project with Gradle Files

• 运行项目，将在目录\build\intermediates\ndk\debug\lib\armeabi下生成libserial_port.so文件。

  

• 将 so 文件拷贝到\src\main\jniLibs\armeabi目录下。

  

以上 参考 http://blog.youkuaiyun.com/doris_d/article/details/53330838  请尊重原创

你以为好了？其实没有，之后你可能看到会报错，你就要检查你的.c文件对不对，首先我说的是文件名称，其次就是文件里面各个方法 ，你自己要认真看，不能直接抄的哥们，之后可能还是有问题，因为串口通信是要API19的 你的是不是，反正我的不是，百度，说是改版本号，我悄悄告诉你， 就是在 jni中 加入termiso.h文件,就是这样，代码是：

/*
 * Copyright (C) 2008 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#ifndef _TERMIOS_H_
#define _TERMIOS_H_

#include <sys/cdefs.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <stdint.h>
#include <linux/termios.h>

__BEGIN_DECLS

/* Redefine these to match their ioctl number */
#undef  TCSANOW
#define TCSANOW    TCSETS

#undef  TCSADRAIN
#define TCSADRAIN  TCSETSW

#undef  TCSAFLUSH
#define TCSAFLUSH  TCSETSF

static __inline__ int tcgetattr(int fd, struct termios *s)
{
    return ioctl(fd, TCGETS, s);
}

static __inline__ int tcsetattr(int fd, int __opt, const struct termios *s)
{
    return ioctl(fd, __opt, (void *)s);
}

static __inline__ int tcflow(int fd, int action)
{
    return ioctl(fd, TCXONC, (void *)(intptr_t)action);
}

static __inline__ int tcflush(int fd, int __queue)
{
    return ioctl(fd, TCFLSH, (void *)(intptr_t)__queue);
}

static __inline__ pid_t tcgetsid(int fd)
{
    pid_t _pid;
    return ioctl(fd, TIOCGSID, &_pid) ? (pid_t)-1 : _pid;
}

static __inline__ int tcsendbreak(int fd, int __duration)
{
    return ioctl(fd, TCSBRKP, (void *)(uintptr_t)__duration);
}

static __inline__ speed_t cfgetospeed(const struct termios *s)
{
    return (speed_t)(s->c_cflag & CBAUD);
}

static __inline__ int cfsetospeed(struct termios *s, speed_t  speed)
{
    s->c_cflag = (s->c_cflag & ~CBAUD) | (speed & CBAUD);
    return 0;
}

static __inline__ speed_t cfgetispeed(const struct termios *s)
{
    return (speed_t)(s->c_cflag & CBAUD);
}

static __inline__ int cfsetispeed(struct termios *s, speed_t  speed)
{
    s->c_cflag = (s->c_cflag & ~CBAUD) | (speed & CBAUD);
  return 0;
}

static __inline__ void cfmakeraw(struct termios *s)
{
    s->c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL|IXON);
    s->c_oflag &= ~OPOST;
    s->c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
    s->c_cflag &= ~(CSIZE|PARENB);
    s->c_cflag |= CS8;
}

static __inline int cfsetspeed(struct termios* s, speed_t speed) {
  // TODO: check 'speed' is valid.
  s->c_cflag = (s->c_cflag & ~CBAUD) | (speed & CBAUD);
  return 0;
}

//static __inline int tcdrain(int fd) {
//  // A non-zero argument to TCSBRK means "don't send a break".
//  // The drain is a side-effect of the ioctl!
//  return ioctl(fd, TCSBRK, __BIONIC_CAST(static_cast, unsigned long, 1));
//}
__END_DECLS

#endif /* _TERMIOS_H_ */

这样 你在运行一次，看可以不，一般就可以了，哈哈~~

当然之后就是找物理端口，一般是/dev/ttyS2，9600 。当然这要根据你们硬件给你们 协议，当然他给你的也只是波特率就是这个9600，这个/dev/ttyS2 可能不是，这时候问硬件？他当然说不知道，你就要使用串口插上，再连上，进入cmd，

1.输入adb shell 只要你设备连接 就会成功的

2.cd /dev 进入这个文件夹

3.ls 看看有没有你们这个ttyS2  你可找到很多东西，比如ttyS0，ttyS1，ttyS3.... 如果有ttyS2 就说明你成功了额，你就不用看了。

但是我没有成功，没有ttyS2，问朋友说，ttyS1 ，我就把所有的是了一下，结果还是失败，没有办法了，问硬件，是怎么调试的，他说是串口转USB，尼玛！！！！怎么不早说，好吧 只有转了，之后就完了？ 可能还不是，说没有权限，代码里面是写有设置权限的，但是我弄的时候说/dev/ttyUSB0 找不到文件，尼玛！！！这么坑，没有办法 下载个360root助手,root成功，你在打开，就可以看到 root询问你权限，当然 给权限，你看到 就OK了 ，好累，现在还在和硬件调试协议，硬件好坑，协议一点都不标准，回复又慢，坑的不行。给我ASCII 返回我各种符号 ，好难受啊。