Code Example _JNI / HAL

 

 

---

 

 

 

. 1  #ifndef LED_HAL_H__
 2  #define LED_HAL_H__
 . 3  
. 4 #include <Hardware / hardware.h>
 . 5  
. 6  // name HAL layer defines the dynamic libraries 
. 7  #define LED_MODULE_ID "s5pv210_led_hal"
 . 8  
. 9  // need to re-definition of the structure: module and device
 10  
. 11  // define the structure module 
12 is  struct led_hw_module_t {
 13 is      // inherited from the parent class 
14      struct hw_module_t Common;         // first member must be the parent class name must be: Common
 15  
16      // the following is their extended members - ---- custom 
17      int serial_id;
18 is      int led_id;
 . 19  };
 20 is  
21 is  // define the device structure 
22 is  struct led_hw_device_t {
 23 is      // inherited from the parent class 
24      struct hw_device_t Common;         // first member must be the parent class name must be: Common
 25  
26 is      // the following extension members for their custom ----- 
27      int (* open_dev) ();
 28      int (* contrl_dev) ( int ON);
 29  };
 30  
31 is  #endif

 

 

 

 

 

---

 

 

 

 

 

 

  1 #define LOG_TAG "led_jni_log"
  2 #include <utils/Log.h>
  3 #include "jni.h"
  4 #include "led_hal.h"
  5 
  6 struct led_hw_module_t *pmodule = NULL;
  7 struct led_hw_device_t *pdevice = NULL;
  8 
  9 //3，实现接口函数
 10 static jint open_led(JNIEnv *env, jobject thiz) 
 11 {
 12     jint ret;
 13     LOGI("-----------------^_^ %s---------------\n" , __ FUNCTION__);
 14      // . 1, loading a dynamic library hal layer ------ acquisition module objects hal layer
 15      // Name Parameter 1 ---- HAL layer dynamic library
 16      // parameter 2 ---- object pointer points to the address module
 17      // return value success ----- --- 0, --- failed negative 
18 is      RET = hw_get_module (LED_MODULE_ID, ( const  struct hw_module_t **) & pmodule );
 19      IF (RET == 0 ) {    // call succeeds --- get to the target module 
20          LOGI ( " ----------------- hw_get_module the OK ----- ---------- \ n- " );
 21 is  
22 is          // 2, calling the open function module object acquisition device objects
23 is          IF (pmodule! = NULL) {
 24              // address parameters 1 --- hal object module layer
 25              // Parameter 2 --- identifies the device, typically NULL
 26 is              // parameter pointing device objects 3 --- the address pointer 
27              pmodule-> common.methods-> open (& pmodule-> Common, NULL, ( struct hw_device_t **) & pDevice);
 28  
29  
30              // . 3, method calls the open target device, open the device: open_dev 
31 is              IF (pDevice =! NULL)
 32                  pdevice-> open_dev ();
 33 is  
34 is          }
 35  
36      } the else {
 37         LOGI("-----------------hw_get_module error---------------\n");
 38         return -1;
 39     }
 40     
 41 
 42     return 0;
 43 }
 44 
 45 static jint led_on(JNIEnv *env, jobject thiz) 
 46 {
 47     
 48     LOGI("-----------------^_^ %s---------------\n",__FUNCTION__);
 49     if(pdevice != NULL)
 50         pdevice->contrl_dev(1);
 51     return 0;
 52 }
 53 static jint led_off(JNIEnv *env, jobject thiz) 
 54 {
 55     jint ret;
 56     LOGI("-----------------^_^ %s---------------\n",__FUNCTION__);
 57     if(pdevice != NULL)
 58         pdevice->contrl_dev(0);
 59     
 60     return 0;
 61 }
 62 
 63 static jint close_led(JNIEnv *env, jobject thiz) 
 64 {
 65     LOGI("-----------------^_^ %s---------------\n",__FUNCTION__);
 66     if(pdevice != NULL)
 67         pdevice->common.close((struct hw_device_t*)pdevice);
 68     return 0;
 69 }
 70 
 71 
 72 //2,创建映射表
 73 const JNINativeMethod led_jni_methods[] = {
 74     {"openDev", "()I", (void*)open_led},
 75     {"devOn", "()I", (void*)led_on},
 76     {"devOff", "()I", (void*)led_off},
 77     {"closeDev", "()I", (void*)close_led},
 78 };
 79 
 80 //1，实现JNI_Onload函数
 81 jint JNI_OnLoad(JavaVM* vm, void* reserved)
82  {
 83  
84      the JNIEnv the env * = NULL;
 85  
86      LOGI ( " ----------------- ^ _ ^ S -------------% - \ n- " , __ FUNCTION__);
 87      // . 1, environment variables objects ----- environment variable object encapsulates many functions required for programming jni
 88      // parameter 1 - the environment variable address pointer
 89      // parameter 2 - jni version
 90      // return value: --0 success, failure - negative 
91 is      IF (vm-> GetEnv (( void ! **) & the env, JNI_VERSION_1_4) = JNI_OK) {
 92          the LOGE ( " ERROR: vm-> GetEnv failed " );
 93          return -1 ;
 94      }
 95  
96      // Class 2, obtaining the application layer method of local declaration app where
 97      // path parameter ---- class of app 
98      JClass env-CLZ => the FindClass ( " COM / Peter / lowlevel / LedNative " );
 99      IF (CLZ == NULL) {
 100          the LOGE ( " ERROR: vm-> the FindClass failed " );
 101          return - . 1 ;
 102      }
 103  
104      // . 3, and creates a mapping table to map register DVM in
 105      // parameter 1 ----- java class declarations where the native methods
 106      //Parameter 2 ----- address mapping table
 107      // number of parameter 2 ----- method of mapping table
 108      // Return Value: --0 success, failure - Negative 
109      IF (env-> RegisterNatives (CLZ, led_jni_methods, the sizeof (led_jni_methods) / the sizeof (led_jni_methods [ 0 ])) < 0 ) {
 110          the LOGE ( " ERROR: RegisterNatives failed " );
 111         return - . 1 ;
 112      }
 113  
114      return   JNI_VERSION_1_4;
 115  
1 16 }

 

 

---

 

 

 

 1 LOCAL_PATH:= $(call my-dir)
 2 include $(CLEAR_VARS)
 3 
 4 LOCAL_MODULE_TAGS := optional
 5 
 6 LOCAL_MODULE:= libled_jni
 7 
 8 LOCAL_SRC_FILES:=  led_jni.cpp
 9 
10 
11 LOCAL_SHARED_LIBRARIES :=  \
12             libutils     \
13             libhardware
14 
15 LOCAL_C_INCLUDES +=  $(JNI_H_INCLUDE)            //指定头文件:jni.h 的路径
16 
17 include $(BUILD_SHARED_LIBRARY)