A good memory is better than a bad pen------button Light JNI, packaged into so files and used

MTK Platform If you add a button light on the hardware, the third-party app and the framework layer want to call, all need to pass the JNI interface, the specific usage is not the same, here is a brief introduction of my use of the process.

First, you need to add KEYLED.C and header files KeyLed.h two interface functions:

(\HARDWARE\LIBHARDWARE_LEGACY\KEY_LEDS\KEY_LEDS.C)

(\hardware\libhardware_legacy\include\hardware_legacy\keyled.h)

1, Here is a brief introduction to the method of packaging the so file (tool eclipse,ndk):

Put the KEY_LEDS.C and key_leds.h files in the JNI directory in the application, Add the C + + interface Jni_key_leds.cpp,jni_key_leds.h,android.mk file, the directory structure is as follows:

File Description:

ANDROID.MK: (define so name, introduce header file, etc.) as follows

1Local_path:= $ (Call my-dir)2 include $ (clear_vars)3 4Local_module: =jni_key_leds5Local_module_tags: =Optional6 7Local_c_includes + =    8 $ (jni_h_include)9$ (Local_path)/Key_leds.hTen$ (Local_path)/Key_leds.h One$ (Local_path)/pressure.h A      -Local_src_files: =  - Jni_key_leds.cpp the KEY_LEDS.C - pressure.c -  -Local_shared_libraries: =libutils +  -Local_ldlibs: =-Llog +  ALocal_static_libraries: = at  -Local_cflags + = -  -Local_prelink_module: =false -  -Include $ (build_shared_library)

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APPLICATION.MK:

1 app_stl: = gnustl_static2 app_gppflags: =-frtti-fexceptions3 App_abi: = All

App_abi: By default, the NDK's compilation system generates machine code based on the "Armeabi" ABI. You can use App_abi to select a different ABI,

For example, to support the hardware FPU command on ARMV7 devices. You can use App_abi: = armeabi-v7a

Or to support the IA-32 instruction set, you can use App_abi: = x86

Or to support these three, you can use App_abi: = Armeabi armeabi-v7a x86

App_abi: = all compiled

Jni_key_leds.cpp: Introduce interface file and header file, write method interface

1#include <jni.h>2#include <unistd.h>3#include <fcntl.h>4#include <sys/types.h>5#include <sys/stat.h>6 7#include <stdio.h>8#include <stdlib.h>9#include <math.h>Ten#include <string.h> One  A#include"Jni_key_leds.h" -#include"Key_leds.h" -#include"pressure.h" the  -#include <android/log.h> -  - #defineLog_tag "Mainactivity" + #defineLOGD (...) __android_log_print (Android_log_debug, Log_tag, __va_args__) -  + extern "C" { A      at jniexport jint jnicall java_com_elderposition_util_devicemanager_red1ledsexists ( -JNIEnv *env, Jobject obj) { -LOGD ("red1_leds_exists!!!"); -     returnred1_leds_exists (); - } - jniexport jint jnicall java_com_elderposition_util_devicemanager_red2ledsexists ( inJNIEnv *env, Jobject obj) { -LOGD ("red2_leds_exists!!!"); to     returnred2_leds_exists (); + } - ....... the}

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Jni_key_leds.h:

1 #ifndef __jni_key_leds2 #define__jni_key_leds 13 4 #ifdef __cplusplus5 extern "C" {6 #endif7 8 jniexport jint jnicall java_com_elderposition_util_devicemanager_red1ledsexists (9JNIEnv *env, Jobject obj);Ten jniexport jint jnicall java_com_elderposition_util_devicemanager_red2ledsexists ( OneJNIEnv *env, Jobject obj); A}

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KEY_LEDS.C: Interface file, method (Note the method name, the full path of the program with "_" connection)

1#include <stdio.h>2#include <unistd.h>3#include <fcntl.h>4#include <errno.h>5 6 #defineRed1_device "/sys/devices/platform/key_leds/red1_leds_onoff"7 #defineRed2_device "/sys/devices/platform/key_leds/red2_leds_onoff"8 #defineRed3_device "/sys/devices/platform/key_leds/red3_leds_onoff"9 #defineBlue_device "/sys/devices/platform/key_leds/blue_leds_onoff"Ten #defineGreen_device "/sys/devices/platform/key_leds/green_leds_onoff" One   A intred1_leds_exists () - { -     intFD; the  - #ifdef Qemu_hardware -     if(Qemu_check ()) { -         return 1; +     } - #endif +  AFD =Open (Red1_device, O_RDWR); at     if(FD <0) -         return 0; - Close (FD); -     return 1; -}

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Key_leds.h: Receiving oral documents

1 #ifndef _hardware_ir_leds_h2 #define_hardware_ir_leds_h3 4 #if__cplusplus5 extern "C" {6 #endif7 8 intred1_leds_exists ();9 Ten intred2_leds_exists (); One}

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Once the above steps have been completed, the so file is compiled in Eclipse and can be used in third-party apps.

When a third-party app wants to use JNI, it can use files packaged as so in the Lib folder, using the same usage as other APIs:

public class DeviceManager {

static {
System.loadlibrary ("jni_key_leds");//Key point 1, introduction of so file
}

public native int red1ledsexists (); Key point 2, corresponding to each method write interface

public native int red2ledsexists ();

public native int red3ledsexists ();

public native int blueledsexists ();

public native int greenledsexists ();

}

2, the upper layer uses JNI (from Java layer to framework to JNI to HAL to kernel usage process)

A good memory is better than a bad pen------button Light JNI, packaged into so files and used