在 Android 系统源码中自定义系统服务（Custom System Service in AOSP）

配置编译环境（Initial AOSP build environment.）

cd AOSP root dir
source build/envsetup.sh
lunch
2

定义 Service 的 AIDL 文件（Define service AIDL file）

path:frameworks/base/core/java/android/os/
Create IHaoHaoService.aidl file

package android.os;

interface IHaoHaoService {

   void setVal(String key,String value);

   String getVal(String key);
}

修改 Android 模块文件（Modify Android.mk file）

path: frameworks/base/Android.mk

......

## READ ME: ########################################################
##
## When updating this list of aidl files, consider if that aidl is
## part of the SDK API.  If it is, also add it to the list below that
## is preprocessed and distributed with the SDK.  This list should
## not contain any aidl files for parcelables, but the one below should
## if you intend for 3rd parties to be able to send those objects
## across process boundaries.
##
## READ ME: ########################################################
LOCAL_SRC_FILES += \

    ......

    core/java/android/os/IPowerManager.aidl \
    core/java/android/os/IRemoteCallback.aidl \
    core/java/android/os/ISchedulingPolicyService.aidl \
    core/java/android/os/IUpdateLock.aidl \
    core/java/android/os/IUserManager.aidl \
    core/java/android/os/IVibratorService.aidl \
    core/java/android/os/IHaoHaoService.aidl \

    ......

进行模块编译：

~/aosp/android-6.0.1_r1$ mmm frameworks/base

generate IHaoHaoService.java file.

创建 HaoHaoService 文件（Create HaoHaoService file）

path: frameworks/base/services/core/java/com/android/server/
Create HaoHaoService.java file.

package com.android.server;

import android.util.Slog; 
import android.os.RemoteException;
import android.os.IHaoHaoService;
import java.util.HashMap;

public class HaoHaoService extends IHaoHaoService.Stub {
    private static HashMap<String,String> mCache = null;
    private static final String TAG="HaoHaoService";

    public HaoHaoService() {
         mCache = new HashMap<>();
         Slog.d(TAG, "HaoHaoService starting.");
    }

   
    public void setVal(String key, String value) throws RemoteException {
        mCache.put(key, value);
    }

    public String getVal(String key) throws RemoteException {
        return mCache.get(key);
    }

}

注册服务（Register service）

Modify frameworks/base/core/java/android/content/Context.java
Add:

     /**
     * Use with {@link #getSystemService} to retrieve a
     * {@link android.os.IHaoHaoService} for accessing the HaoHao service.
     *
     * @see #getSystemService
     * @hide
     */
    public static final String HAOHAO_SERVICE = "haohao";

Modify frameworks/base/services/java/com/android/server/SystemServer.java
Find function startOtherServices()
Add:

            try {
                Slog.i(TAG, "***HaoHao Service***");
                ServiceManager.addService(Context.HAOHAO_SERVICE, new HaoHaoService());
            } catch (Throwable e) {
                Slog.e(TAG, "Failure starting HaoHao Service", e);
            }

Create HaoHaoServiceManager.java file

path: frameworks/base/core/java/android/app/

package android.app;

/**
 * Created by haohao on 17/10/2.
 */
import android.annotation.SdkConstant;
import android.annotation.SystemApi;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.RemoteException;
import android.os.IHaoHaoService;
import android.util.Log;

public class HaoHaoServiceManager {

    private static final String TAG = "HaoHaoServiceManager";
    private IHaoHaoService mService;

    public HaoHaoServiceManager(Context context, IHaoHaoService service){
        mService = service;
    }

    public void setVal(String key,String value){

        try {

            mService.setVal(key,value);

        } catch(Exception e){

            Log.e(TAG, e.toString());

            e.printStackTrace();
        }

    }
    public String getVal(String key){
        try {

            return mService.getVal(key);

        } catch(Exception e){
            
            Log.e(TAG, e.toString());
            e.printStackTrace();
        }
        return null;
    }
}

Register service in SystemServiceRegistry.java file

path: frameworks/base/core/java/android/app/SystemServiceRegistry.java
Add:

import android.os.IHaoHaoService;
      
        ......

         registerService(Context.HAOHAO_SERVICE, HaoHaoServiceManager.class,
                new CachedServiceFetcher<HaoHaoServiceManager>() {
                    @Override
                    public HaoHaoServiceManager createService(ContextImpl ctx) {
                        IBinder binder = ServiceManager.getService(Context.HAOHAO_SERVICE);
                        IHaoHaoService service = IHaoHaoService.Stub.asInterface(binder);
                        return new HaoHaoServiceManager(ctx, service);
            }});

        ......

Modify SePolicy Build Check

path: external/sepolicy/service.te

Add:

type haohao_service, system_api_service, system_server_service, service_manager_type;

path: external/sepolicy/service_contexts

Add:

haohao u:object_r:haohao_service:s0

service_contexts

accessibility                             u:object_r:accessibility_service:s0
account                                   u:object_r:account_service:s0
activity                                  u:object_r:activity_service:s0
alarm                                     u:object_r:alarm_service:s0
haohao                                    u:object_r:haohao_service:s0
android.security.keystore                 u:object_r:keystore_service:s0
android.service.gatekeeper.IGateKeeperService    u:object_r:gatekeeper_service:s0

Update api and build

~/aosp/android-6.0.1_r1$ make update-api -j8

~/aosp/android-6.0.1_r1$ make -j8

Test service in your Activity

    @Override
    public void onCreate() {
        super.onCreate();

        mHaoHaoServiceManager = (HaoHaoServiceManager)getSystemService(Context.HAOHAO_SERVICE);
        mHaoHaoServiceManager.setVal("haohao", "Android Developer");