ok6410Android应用程序:(jni方式)控制LED/GPIO Linux

前面文章介绍了如何编写led驱动模块,这里介绍如何编写一个Android应用程序去控制LED/GPIO.小弟不才,不会用JAVA,所以这个应用程序是用C写的,然后用java实现了几个按钮,代码和外观都比较丑陋,大家勿喷!费话少说,贴代码!
1.新建eclipse项目

2.在led.java中加入public static native int led(int i, int j);
led.java:

package com.example.led; import android.os.Bundle; import android.app.Activity; import android.view.Menu; public class LED extends Activity {@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.led); }@Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.led, menu); return true; }public static native int led(int i, int j); }

3.编译项目文件,bin目录下会生成led.apk.
4.终端进入项目目录,新建jni目录

5.利用javah命令生成头文件,该头文件中包含了符合jni格式的函数名,
javah -classpath bin/classes -d jni com.example.led.LED

6. jni目录下新建led.c
此c程序实际上是linux下的LED测试程序,函数入口更换为上面javah生成的函数名,以便java调用.

#include #include #include #include #include #include #include #define LOG_TAG "LED"//android logcat #defineLOGI(...)__android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__) #defineLOGE(...)__android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)//int main(int argc, char **argv) jint JNICALL Java_com_example_led_Led_led(JNIEnv *env, jclass thiz, jint led_nu, jint on) { int fd; fd = open("/dev/leds0", O_RDWR); if(fd < 0) printf("Can't open /dev/leds!\n"); ioctl(fd, on, led_nu); LOGI("led_nu=%d,state=%d\n", led_nu, on); close(fd); return 0; }

7. 在jni目录下新建Andorid.mk[实际上是为led.c编写makefile]
Android.mk:

LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS) LOCAL_MODULE := LED LOCAL_SRC_FILES := led.c LOCAL_LDLIBS := -llog LOCAL_C_INCLUDES := $(MY_ANDROID_SOURCE)/frameworks/base/core/jni/android/graphics \ include $(BUILD_SHARED_LIBRARY)

用ndk-build编译生成so库

8.回到eclipse中,将生成的so库添加进led.java中
led.java:

package com.example.led; import android.os.Bundle; import android.app.Activity; import android.view.Menu; public class LED extends Activity {@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.led); }@Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.led, menu); return true; }public static native int led(int i, int j); static { System.loadLibrary("LED"); } }

9. 修改布局,在led.xml中为界面添加按钮
res --> layout --> led.xml:

10. 在led.java中添加监听按键代码(最终的led.java)

package com.example.led; import android.app.Activity; import android.content.Intent; import android.net.Uri; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.ToggleButton; import android.util.Log; import android.widget.CompoundButton.OnCheckedChangeListener; public class Led extends Activity { private static final String TAG = "LED"; private ToggleButton button1; private ToggleButton button2; private ToggleButton button3; private ToggleButton button4; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.led); Log.w(TAG,"layout"); button1 = (ToggleButton)findViewById(R.id.btn1); button2 = (ToggleButton)findViewById(R.id.btn2); button3 = (ToggleButton)findViewById(R.id.btn3); button4 = (ToggleButton)findViewById(R.id.btn4); Log.w(TAG,"button"); button1.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { if (button1.isChecked()) { Log.w(TAG,"----led1 on"); led(0, 1); } else { Log.w(TAG,"----led1 off"); led(0, 0); } } }); button2.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { if (button2.isChecked()) { Log.w(TAG,"----led2 on"); led(1, 1); } else { Log.w(TAG,"----led2 off"); led(1, 0); } } }); button3.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { if (button3.isChecked()) { Log.w(TAG,"----led3 on"); led(2, 1); } else { Log.w(TAG,"----led3 off"); led(2, 0); } } }); button4.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { if (button4.isChecked()) { Log.w(TAG,"----led4 on"); led(3, 1); } else { Log.w(TAG,"-----led4 off"); led(3, 0); } } }); }public static native int led(int i, int j); static { System.loadLibrary("LED"); }}

11. 编译整个项目,在bin目录下生成led.apk, 拷贝到开发板中就可以安装运行了.
注意:安装led.apk前,请先加载led.ko模块,并确认编译模块所用的内核版本和android版本一至.另外,还需要通过串口修改 /dev/leds0 的权限为 777.(chmod 777 /dev/leds0),否则led.c中的open("/dev/leds0", o_RDWR)会失败.
【ok6410Android应用程序:(jni方式)控制LED/GPIO】