2.Android硬件访问服务编写系统代码【转】
本文转载自:https://blog.csdn.net/qq_33443989/article/details/76696772
版权声明：本文为博主(Tower)自学笔记，欢迎转载！ :-) https://blog.csdn.net/qq_33443989/article/details/76696772
1>. 实现用硬件访问服务硬件的代码-没有HAL层
1<. AIDL: Android Interface Definition Language，即Android接口定义语言
AIDL_百度解释
2<. 编写代码
1<. ILedService.aidl
1<. 路径: android_system_code/frameworks/base/core/java/android/os/
2<. 作用: 生成我们所需要的接口文件
3<. 实现
1<. 代码内容
2<. 上传 ：Android_Soruce/franeworks/base/core/java/android/os
3<. 修改 ：Android_Soruce/franeworks/base/Android.mk文件
+ core/java/android/os/ILedService.aidl
[前期准备]：在Android源码目录
. setenv
lunch
mmm .[dir]
4<.[出现问题]：
make: Entering directory /work/android-5.0.2'
Aidl: framework <= frameworks/base/./core/java/android/os/ILedService.aidl
unable to open out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/src/core/java/android/os/ILedService.java for write
make: *** [out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/src/core/java/android/os/ILedService.java] Error 1
make: Leaving directory/work/android-5.0.2’
[解决方法]：
su : 改为root用户
5<. 最终得到了 ILedService.java
1<.路径: android_system_code\out\target\common\obj\JAVA_LIBRARIES\
framework_intermediates\src\core\java\android\os
2<. 解析IXxxxxService.java
1<. 会得到一个Stub抽象类和一个Proxy静态内部类
2<. asInterface() : 转换函数一枚
3<. ledCtrl() : 已经实现了binder进程通信的内部函数，并且可以覆写
3<. 如何使用IXxxxxService.java
1<. 初始化
ILedService iLedService;
iLedService = iLedService.stub.asInterface(ServiceManager.getService(“led”));
2<. 后期使用
iLedService.ledCtrl()：直接使用，这样使用并不会直接操作我们的HAL层，而是发给相应的ledService进程，使其处理
2<. LedService.java
1<. 路径: android_system_code\frameworks\base\services\core\java\com\android\server\
2<. 作用: 用于向系统注册该服务,提供了APP访问硬件的桥梁
3<. 实现:
1<. 定义类 ： 继承于aidl文件接口.抽象类Stub
public class LedService extends ILedService.Stub
2<. 实现aidl接口定义的函数
public int ledCtrl(int which, int status) throws android.os.RemoteException
3<. 实现构造方法：例如打开设备 native_ledOpen();
/* 以下是修改其他文件，使其注册LedService.java */
4<. systemServer.java
1<. 路径: android_system_code\frameworks\base\services\java\com\android\server\
SystemServer.java
2<. startOtherServices()
1.添加 LedService Led = null;
2.添加下面代码
/* 2017.08.04 Tower Modify*/
Slog.i(TAG, “Led Service”);
Led = new LedService();
ServiceManager.addService(“Led”, Led);
/* Modift End */
3<. 实现com_android_server_LedService.cpp
1<. 路径: android_system_code\frameworks\base\services\core\jni\
2<. 作用: 属于JNI层,注册本地方法,供LedService.java使用
3<. 实现: 同其他的JNI一样, 只是多了一个注册函数,给onload.cpp使用
1<. int register_android_server_LedService(JNIEnv *env)
/* 以下是修改其他文件，使其注册LedService.java */
4<. onload.cpp
1<. 路径: android_system_code\frameworks\base\services\core\jni\onload.cpp
2<. JNI_OnLoad()
register_android_server_LedService(env);
3<. 编译:
1<. 自己写的文件:
File_name Full_Dir
com_android_server_LedService.cpp android_system_code/frameworks/base/services/core/jni/
LedService.java android_system_code/frameworks/base/services/core/java/com/android/server/
ILedService.aidl android_system_code/frameworks/base/core/java/android/os/
ILedService.java android_system_code/out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/src/core/java/android/os/
2<. 修改的文件
File_name Full_Dir
onload.cpp android_system_code/frameworks/base/services/core/jni/
systemServer.java android_system_code/frameworks/base/services/java/com/android/server/
3<. 同时修改对应目录下的Android.mk
1<. 编译 android_system_code/frameworks/base/services
mmm.
[为什么]:因为android_system_code/frameworks/base/services/Android.mk已经包含
1<. include (wildcard(wildcard(LOCAL_PATH)/*/jni/Android.mk)
2<. include (patsubst(patsubst(LOCAL_PATH)/%/Android.mk,$(services))
[所以]:
1<. com_android_server_LedService.cpp
android_system_code/frameworks/base/services/core/jni/Android.mk 需要修改
2<. LedService.java
android_system_code/frameworks/base/services/core/Android.mk 不需要修改
[补充]:android_system_code/frameworks/base/services/android.mk里面
LOCAL_MODULE:= libandroid_servers : 这个库指的就是onload.cpp
4<. make snod : 会在out目录下创建image
5<. ./gen-img.sh : 可以直接在源码目录下得到image
4<. 烧写内核:
示例代码
1<. LedService.java –APP层
package com.android.server;
import android.os.ILedService;
//import android.os.Vibrator;
/*
import android.os.IBinder;
*/
public class LedService extends ILedService.Stub {
private static final String TAG = "LedService";
/* call native c function to access hardware */
public int ledCtrl(int which, int status) throws android.os.RemoteException {
return native_ledCtrl(which, status);
}
public LedService() {
native_ledOpen();
}
/* declaration native method*/
public static native int native_ledCtrl(int which, int status);
public static native int native_ledOpen();
public static native void native_ledClose();
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
2<. SystemServer.java –SYS层
package com.android.server;
...
import android.app.ActivityManagerNative;
import android.app.ActivityThread;
import android.app.IAlarmManager;
import android.app.INotificationManager;
import android.app.usage.UsageStatsManagerInternal;
import android.bluetooth.BluetoothAdapter;
...
public final class SystemServer {
...
private void startOtherServices() {
VibratorService vibrator = null;
LedService leds = null;
IAlarmManager alarm = null;
MountService mountService = null;
NetworkManagementService networkManagement = null;
NetworkStatsService networkStats = null;
NetworkPolicyManagerService networkPolicy = null;
ConnectivityService connectivity = null;
...
try {
Slog.i(TAG, "Reading configuration...");
SystemConfig.getInstance();
try {
...
Slog.i(TAG, "Vibrator Service");
vibrator = new VibratorService(context);
ServiceManager.addService("vibrator", vibrator);
/* 2017.08.04 Tower Modify*/
Slog.i(TAG, "Led Service");
leds = new LedService();
ServiceManager.addService("leds", leds);
/* Modift End */
}
}
...
}
...
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
3<. onload.cpp –JNI层
namespace android {
int register_android_server_location_GpsLocationProvider(JNIEnv* env);
int register_android_server_location_FlpHardwareProvider(JNIEnv* env);
int register_android_server_connectivity_Vpn(JNIEnv* env);
int register_android_server_hdmi_HdmiCecController(JNIEnv* env);
int register_android_server_tv_TvInputHal(JNIEnv* env);
int register_android_server_PersistentDataBlockService(JNIEnv* env);
int register_android_server_fingerprint_FingerprintService(JNIEnv* env);
int register_android_server_Watchdog(JNIEnv* env);
int register_android_server_LedService(JNIEnv *env);
...
}
extern "C" jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
JNIEnv* env = NULL;
jint result = -1;
if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {
ALOGE("GetEnv failed!");
return result;
}
register_android_server_LightsService(env);
register_android_server_AlarmManagerService(env);
register_android_server_UsbDeviceManager(env);
register_android_server_UsbHostManager(env);
register_android_server_VibratorService(env);
register_android_server_SystemServer(env);
register_android_server_location_GpsLocationProvider(env);
register_android_server_location_FlpHardwareProvider(env);
register_android_server_connectivity_Vpn(env);
...
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
4<. ILedService.aidl –JNI层
package android.os;
/** {@hide} */
interface ILedService
{
int ledCtrl(int which, int status);
}
1
2
3
4
5
6
7
5<. com_android_server_LedService.cpp –JNI层
/*
* Copyright (C) 2017 The Android Open Source Project
* Author : Fogost路Tower
* Time : 2017.08.04
*/
#define LOG_TAG "LedService"
#include "jni.h"
#include "JNIHelp.h"
#include <utils/misc.h>
#include <utils/Log.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
namespace android
{
static jint g_iFd;
jint ledOpen(JNIEnv *env, jobject cls)
{
g_iFd = open("/dev/leds", O_RDWR);
ALOGI("native ledopen.. %d", g_iFd);
if (g_iFd >= 0) {
return 0;
}else {
return -1;
}
}
void ledClose(JNIEnv *env, jobject cls)
{
ALOGI("native ledClose..");
close(g_iFd);
}
jint ledCtrl(JNIEnv *env, jobject cls, jint which, jint status)
{
int ret = ioctl(g_iFd, status, which);
ALOGI("native ledCtrl.. which = %d status = %d ret = %d: ", which, status, ret);
return ret;
}
static const JNINativeMethod method_table[] = {
{ "native_ledOpen" , "()I" , (void*)ledOpen},
{ "native_ledClose", "()V" , (void*)ledClose},
{ "native_ledCtrl" , "(II)I", (void*)ledCtrl},
};
int register_android_server_LedService(JNIEnv *env)
{
return jniRegisterNativeMethods(env, "com/android/server/LedService",
method_table, NELEM(method_table));
}
};
