Android教程網
設為首頁|加入收藏
  1. 首頁
  2. Android 技術
  3. Android 手機
  4. Android 系統教程
  5. Android 游戲
 Android教程網 >> Android技術 >> 關於Android編程 >> Android 驅動開發系列四

Android 驅動開發系列四

編輯：關於Android編程

時隔多日，終於都抽出時間來寫blog了。廢話不多說，接著上一篇，這裡將介紹如何編寫HAL層（硬件抽象層）對應的JNI方法。

這裡提到的都是在ICS源碼裡編譯的。

 

1、定義JNI層接口
進入到android-4.0.4_r1.2/hardware/libhardware/include/hardware目錄，並創建 ttt.h 文件，內容如下：

[cpp]
#ifndef ANDROID_TTT_INTERFACE_H  
#define ANDROID_TTT_INTERFACE_H  
#include <hardware/hardware.h>  
 
__BEGIN_DECLS 
 
// 定義模塊ID  
#define HELLO_HARDWARE_MODULE_ID    "ttt"  
 
// 硬件模塊結構體  
struct ttt_module_t{ 
    struct hw_module_t common; 
}; 
 
// hardware interface struct  
struct ttt_device_t{ 
    struct hw_device_t common; 
    int fd; 
    int(*set_val)(struct ttt_device_t* dev, int val); 
    int(*get_val)(struct ttt_device_t* dev, int* val); 
}; 
 
__END_DECLS 
 
 
#endif 

#ifndef ANDROID_TTT_INTERFACE_H
#define ANDROID_TTT_INTERFACE_H
#include <hardware/hardware.h>

__BEGIN_DECLS

// 定義模塊ID
#define HELLO_HARDWARE_MODULE_ID "ttt"

// 硬件模塊結構體
struct ttt_module_t{
    struct hw_module_t common;
};

// hardware interface struct
struct ttt_device_t{
 struct hw_device_t common;
 int fd;
 int(*set_val)(struct ttt_device_t* dev, int val);
 int(*get_val)(struct ttt_device_t* dev, int* val);
};

__END_DECLS


#endif

2、實現JNI層接口功能
進入到android-4.0.4_r1.2/frameworks/base/services/jni目錄，並創建com_android_server_TTTService.cpp文件，其內容如下：

[cpp]
#define LOG_TAG     "TTTService"  
 
#include "jni.h"  
#include "JNIHelp.h"  
#include "android_runtime/AndroidRuntime.h"  
#include <utils/misc.h>  
#include <utils/Log.h>  
#include <hardware/hardware.h>  
#include <hardware/ttt.h>  
#include <stdio.h>  
 
namespace android 
{ 
    struct ttt_device_t* ttt_device = NULL; 
 
    // through the HAL interface to set the register value  
    static void ttt_setVal(JNIEnv* env, jobject clazz, jint value){ 
        int val = value; 
        LOGI("TTT JNI: set value %d to device.", val); 
        if(!ttt_device){ 
            LOGI("TTT JNI: device is not open."); 
            return; 
        } 
 
        ttt_device->set_val(ttt_device, val); 
    } 
 
    // through the HAL interface to read the register value  
    static jint ttt_getVal(JNIEnv* env, jobject clazz){ 
        int val = 0; 
        if(!ttt_device){ 
            LOGI("TTT JNI: device is not open."); 
            return val; 
        } 
        ttt_device->get_val(ttt_device, &val); 
 
        LOGI("TTT JNI: get value %d from device.", val); 
 
        return val; 
    } 
 
    // through the HAL interface to open the hardware device  
    static inline int ttt_device_open(const hw_module_t* module, struct ttt_device_t** device){ 
        return module->methods->open(module, HELLO_HARDWARE_MODULE_ID, (struct hw_device_t**)device); 
    } 
 
    // throught the hardware module ID to load the HAL module and open the device  
    static jboolean ttt_init(JNIEnv* env, jclass clazz){ 
        ttt_module_t* module; 
 
        LOGI("TTT JNI: initializing..."); 
        if(hw_get_module(HELLO_HARDWARE_MODULE_ID, (const struct hw_module_t**)&module) == 0){ 
            LOGI("TTT JNI: ttt stub found."); 
            if(ttt_device_open(&(module->common), &ttt_device) == 0){ 
                LOGI("TTT JNI: ttt device is open."); 
                return 0; 
            } 
            LOGE("TTT JNI: failed to open ttt device."); 
            return -1; 
        } 
 
        LOGE("TTT JNI: failed to get ttt stub module."); 
        return -1; 
    } 
 
    // JNI methods table  
    static const JNINativeMethod method_table[] = { 
        {"init_native", "()Z", (void*)ttt_init}, 
        {"setVal_native", "(I)V", (void*)ttt_setVal}, 
        {"getVal_native", "()I", (void*)ttt_getVal}, 
    }; 
 
    // regist JNI method  
    int register_android_server_TTTService(JNIEnv* env){ 
        return jniRegisterNativeMethods(env, "com/android/server/TTTService", method_table, NELEM(method_table)); 
    } 
}; 

#define LOG_TAG     "TTTService"

#include "jni.h"
#include "JNIHelp.h"
#include "android_runtime/AndroidRuntime.h"
#include <utils/misc.h>
#include <utils/Log.h>
#include <hardware/hardware.h>
#include <hardware/ttt.h>
#include <stdio.h>

namespace android
{
    struct ttt_device_t* ttt_device = NULL;

    // through the HAL interface to set the register value
    static void ttt_setVal(JNIEnv* env, jobject clazz, jint value){
        int val = value;
        LOGI("TTT JNI: set value %d to device.", val);
        if(!ttt_device){
            LOGI("TTT JNI: device is not open.");
            return;
        }

        ttt_device->set_val(ttt_device, val);
    }

    // through the HAL interface to read the register value
    static jint ttt_getVal(JNIEnv* env, jobject clazz){
        int val = 0;
        if(!ttt_device){
            LOGI("TTT JNI: device is not open.");
            return val;
        }
        ttt_device->get_val(ttt_device, &val);

        LOGI("TTT JNI: get value %d from device.", val);

        return val;
    }

    // through the HAL interface to open the hardware device
    static inline int ttt_device_open(const hw_module_t* module, struct ttt_device_t** device){
        return module->methods->open(module, HELLO_HARDWARE_MODULE_ID, (struct hw_device_t**)device);
    }

    // throught the hardware module ID to load the HAL module and open the device
    static jboolean ttt_init(JNIEnv* env, jclass clazz){
        ttt_module_t* module;

        LOGI("TTT JNI: initializing...");
        if(hw_get_module(HELLO_HARDWARE_MODULE_ID, (const struct hw_module_t**)&module) == 0){
            LOGI("TTT JNI: ttt stub found.");
            if(ttt_device_open(&(module->common), &ttt_device) == 0){
                LOGI("TTT JNI: ttt device is open.");
                return 0;
            }
            LOGE("TTT JNI: failed to open ttt device.");
            return -1;
        }

        LOGE("TTT JNI: failed to get ttt stub module.");
        return -1;
    }

    // JNI methods table
    static const JNINativeMethod method_table[] = {
        {"init_native", "()Z", (void*)ttt_init},
        {"setVal_native", "(I)V", (void*)ttt_setVal},
        {"getVal_native", "()I", (void*)ttt_getVal},
    };

    // regist JNI method
    int register_android_server_TTTService(JNIEnv* env){
        return jniRegisterNativeMethods(env, "com/android/server/TTTService", method_table, NELEM(method_table));
    }
};
 

3、添加JNI初始化調用
修改android-4.0.4_r1.2/frameworks/base/services/jni目錄下的 onload.cpp 文件，在 JNI_OnLoad函數中的return之前添加下面一句：

[cpp]
register_android_server_TTTService(env); 

register_android_server_TTTService(env);同時，在該文件中的namespace中添加下面一句聲明：

[cpp]
int register_android_server_TTTService(JNIEnv* env); 

int register_android_server_TTTService(JNIEnv* env);

這樣，在系統初始化時，就會調用register_android_server_TTTService方法來加載JNI方法了。

 

4、添加編譯JNI的配置
修改android-4.0.4_r1.2/frameworks/base/services/jni目錄下的 Android.mk 文件，在 LOCAL_SRC_FILES 變量中添加下面一行：

[cpp]
com_android_server_TTTService.cpp \ 

    com_android_server_TTTService.cpp \這裡是添加編譯配置。

 

5、開始編譯
[cpp]
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# . build/envsetup.sh  
including device/moto/stingray/vendorsetup.sh 
including device/moto/wingray/vendorsetup.sh 
including device/samsung/crespo4g/vendorsetup.sh 
including device/samsung/crespo/vendorsetup.sh 
including device/samsung/maguro/vendorsetup.sh 
including device/samsung/smdkc110/vendorsetup.sh 
including device/samsung/smdkv210/vendorsetup.sh 
including device/samsung/torospr/vendorsetup.sh 
including device/samsung/toro/vendorsetup.sh 
including device/samsung/tuna/vendorsetup.sh 
including device/ti/panda/vendorsetup.sh 
including sdk/bash_completion/adb.bash 
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# 

root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# . build/envsetup.sh
including device/moto/stingray/vendorsetup.sh
including device/moto/wingray/vendorsetup.sh
including device/samsung/crespo4g/vendorsetup.sh
including device/samsung/crespo/vendorsetup.sh
including device/samsung/maguro/vendorsetup.sh
including device/samsung/smdkc110/vendorsetup.sh
including device/samsung/smdkv210/vendorsetup.sh
including device/samsung/torospr/vendorsetup.sh
including device/samsung/toro/vendorsetup.sh
including device/samsung/tuna/vendorsetup.sh
including device/ti/panda/vendorsetup.sh
including sdk/bash_completion/adb.bash
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2#[cpp] view plaincopyprint?root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# mmm frameworks/base/services/jni 
============================================ 
PLATFORM_VERSION_CODENAME=REL 
PLATFORM_VERSION=4.0.4 
TARGET_PRODUCT=full 
TARGET_BUILD_VARIANT=eng 
TARGET_BUILD_TYPE=release 
TARGET_BUILD_APPS= 
TARGET_ARCH=arm 
TARGET_ARCH_VARIANT=armv7-a 
HOST_ARCH=x86 
HOST_OS=linux 
HOST_BUILD_TYPE=release 
BUILD_ID=IMM76I 
============================================ 
make:進入目錄'/home/brantyou/workspace/android-4.0.4_r1.2' 
target thumb C++: libandroid_servers <= frameworks/base/services/jni/com_android_server_HelloService.cpp 
target thumb C++: libandroid_servers <= frameworks/base/services/jni/com_android_server_TTTService.cpp 
target thumb C++: libandroid_servers <= frameworks/base/services/jni/onload.cpp 
make: *** 沒有規則可以創建“out/target/product/generic/obj/SHARED_LIBRARIES/libandroid_servers_intermediates/LINKED/libandroid_servers.so”需要的目標“out/target/product/generic/obj/lib/libsystem_server.so”。 停止。 
make:離開目錄“/home/brantyou/workspace/android-4.0.4_r1.2” 
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2#  

root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# mmm frameworks/base/services/jni
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=4.0.4
TARGET_PRODUCT=full
TARGET_BUILD_VARIANT=eng
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm
TARGET_ARCH_VARIANT=armv7-a
HOST_ARCH=x86
HOST_OS=linux
HOST_BUILD_TYPE=release
BUILD_ID=IMM76I
============================================
make:進入目錄'/home/brantyou/workspace/android-4.0.4_r1.2'
target thumb C++: libandroid_servers <= frameworks/base/services/jni/com_android_server_HelloService.cpp
target thumb C++: libandroid_servers <= frameworks/base/services/jni/com_android_server_TTTService.cpp
target thumb C++: libandroid_servers <= frameworks/base/services/jni/onload.cpp
make: *** 沒有規則可以創建“out/target/product/generic/obj/SHARED_LIBRARIES/libandroid_servers_intermediates/LINKED/libandroid_servers.so”需要的目標“out/target/product/generic/obj/lib/libsystem_server.so”。 停止。
make:離開目錄“/home/brantyou/workspace/android-4.0.4_r1.2”
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2#
矮油~~~這裡出錯了，提示沒有找到 libsystem_server.so 文件。
執行下面的命令，生成 libsystem_server.so 文件：

[cpp]
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# make libsystem_server 

root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# make libsystem_server生成之後的提示：

[cpp]
Install: out/target/product/generic/system/lib/libvorbisidec.so 
Install: out/target/product/generic/system/lib/libstagefright_yuv.so 
Install: out/target/product/generic/system/lib/libdrmframework.so 
Install: out/target/product/generic/system/lib/libchromium_net.so 
Install: out/target/product/generic/system/lib/libstagefright_amrnb_common.so 
Install: out/target/product/generic/system/lib/libstagefright_enc_common.so 
Install: out/target/product/generic/system/lib/libstagefright_avc_common.so 
Install: out/target/product/generic/system/lib/libstagefright.so 
Install: out/target/product/generic/system/lib/libstagefright_omx.so 
Install: out/target/product/generic/system/lib/libmediaplayerservice.so 
Install: out/target/product/generic/system/lib/libinput.so 
Install: out/target/product/generic/system/lib/libsystem_server.so 
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2#  

Install: out/target/product/generic/system/lib/libvorbisidec.so
Install: out/target/product/generic/system/lib/libstagefright_yuv.so
Install: out/target/product/generic/system/lib/libdrmframework.so
Install: out/target/product/generic/system/lib/libchromium_net.so
Install: out/target/product/generic/system/lib/libstagefright_amrnb_common.so
Install: out/target/product/generic/system/lib/libstagefright_enc_common.so
Install: out/target/product/generic/system/lib/libstagefright_avc_common.so
Install: out/target/product/generic/system/lib/libstagefright.so
Install: out/target/product/generic/system/lib/libstagefright_omx.so
Install: out/target/product/generic/system/lib/libmediaplayerservice.so
Install: out/target/product/generic/system/lib/libinput.so
Install: out/target/product/generic/system/lib/libsystem_server.so
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# 好了，這個問題解決了，我們繼續編譯這個JNI。

[cpp]
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# mmm frameworks/base/services/jni 
============================================ 
PLATFORM_VERSION_CODENAME=REL 
PLATFORM_VERSION=4.0.4 
TARGET_PRODUCT=full 
TARGET_BUILD_VARIANT=eng 
TARGET_BUILD_TYPE=release 
TARGET_BUILD_APPS= 
TARGET_ARCH=arm 
TARGET_ARCH_VARIANT=armv7-a 
HOST_ARCH=x86 
HOST_OS=linux 
HOST_BUILD_TYPE=release 
BUILD_ID=IMM76I 
============================================ 
make:進入目錄'/home/brantyou/workspace/android-4.0.4_r1.2' 
target SharedLib: libandroid_servers (out/target/product/generic/obj/SHARED_LIBRARIES/libandroid_servers_intermediates/LINKED/libandroid_servers.so) 
target Symbolic: libandroid_servers (out/target/product/generic/symbols/system/lib/libandroid_servers.so) 
target Strip: libandroid_servers (out/target/product/generic/obj/lib/libandroid_servers.so) 
Install: out/target/product/generic/system/lib/libandroid_servers.so 
make:離開目錄“/home/brantyou/workspace/android-4.0.4_r1.2” 
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# 

root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# mmm frameworks/base/services/jni
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=4.0.4
TARGET_PRODUCT=full
TARGET_BUILD_VARIANT=eng
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm
TARGET_ARCH_VARIANT=armv7-a
HOST_ARCH=x86
HOST_OS=linux
HOST_BUILD_TYPE=release
BUILD_ID=IMM76I
============================================
make:進入目錄'/home/brantyou/workspace/android-4.0.4_r1.2'
target SharedLib: libandroid_servers (out/target/product/generic/obj/SHARED_LIBRARIES/libandroid_servers_intermediates/LINKED/libandroid_servers.so)
target Symbolic: libandroid_servers (out/target/product/generic/symbols/system/lib/libandroid_servers.so)
target Strip: libandroid_servers (out/target/product/generic/obj/lib/libandroid_servers.so)
Install: out/target/product/generic/system/lib/libandroid_servers.so
make:離開目錄“/home/brantyou/workspace/android-4.0.4_r1.2”
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2#很好，這一次已經順利的編譯完了。


下面我們需要重新打包這個 system.img，包我們編寫的JNI方法包含進去：

[cpp]
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# make snod 
============================================ 
PLATFORM_VERSION_CODENAME=REL 
PLATFORM_VERSION=4.0.4 
TARGET_PRODUCT=full 
TARGET_BUILD_VARIANT=eng 
TARGET_BUILD_TYPE=release 
TARGET_BUILD_APPS= 
TARGET_ARCH=arm 
TARGET_ARCH_VARIANT=armv7-a 
HOST_ARCH=x86 
HOST_OS=linux 
HOST_BUILD_TYPE=release 
BUILD_ID=IMM76I 
============================================ 
make snod: ignoring dependencies 
Target system fs image: out/target/product/generic/system.img 
out/target/product/generic/system.img total size is 44107008 
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2#  

root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# make snod
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=4.0.4
TARGET_PRODUCT=full
TARGET_BUILD_VARIANT=eng
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm
TARGET_ARCH_VARIANT=armv7-a
HOST_ARCH=x86
HOST_OS=linux
HOST_BUILD_TYPE=release
BUILD_ID=IMM76I
============================================
make snod: ignoring dependencies
Target system fs image: out/target/product/generic/system.img
out/target/product/generic/system.img total size is 44107008
root@brantyou-ubuntu:~/workspace/android-4.0.4_r1.2# 這樣就成功的把我們編寫的JNI打包到 system.img中了。

 

 

  1. 上一頁:
  2. 下一頁:
關於Android編程
Android編程入門Android技術基礎Android資訊關於Android編程Android開發Android開發環境Android開發實例
相關文章
熱門文章
Cocos2D-Android-1之源碼詳解：16.ParticleTest Android EventBus源碼解析 帶你深入理解EventBus Android 發送HTTP GET POST 請求以及通過 MultipartEntityBuilder 上傳文件（二） android學習筆記4-Spinner android 中PopupMenu 的簡單使用 Android四大基本組件介紹與生命周期
Android 自定義ProgressDialog進度條對話框用法詳解

ProgressDialog的基本用法ProgressDialog為進度
Android Fragment的使用方法(翻譯)

可以分為下面的幾部分：使用支持庫創建一個Fragment創建一個動態UI
Android中MVP的初步認識與簡單用法

概述認識MVP模式MVP 模式實際上指的是 Model-View-Pre
微信中刪除的聊天記錄如何找回

微信中刪除的聊天記錄如何找回？相信大家都有過誤刪了重要的微
閱讀排行版
Copyright © Android教程網 All Rights Reserved