[Android][Framework] 添加系统服务

新博客地址
http://wossoneri.github.io/2018/09/15/[Android][Framework]create-system-service/

做系统开发,有时候需要自己定义一些接口供App使用, 同时为了方便维护管理,就会需要自己建立一个服务,把新的功能集中在一起。下面就是新建一个系统服务的基本步骤。

  1. 添加接口

    frameworks/base/core/java/android/app/IDemoManager.aidl

    package android.app;
    
    interface IDemoManager
    {
        int getCpuTemperature();
    }
    
  2. 添加服务,实现aidl文件定义的接口

    frameworks/base/services/core/java/com/android/server/DemoManagerService.java

    package com.android.server;
    
    import android.app.IDemoManager;
    import android.content.Context;
    import android.util.Slog;
    
    public class DemoManagerService extends IDemoManager.Stub {
        private Context mContext;
    
        public DemoManagerService(Context context) {
            mContext = context;
            Slog.d("Demo", "Construct");
        }
    
        @Override
        public int getCpuTemperature() {
            return 100; // Test code
        }
    }
    
  3. 添加对应的Manager

    frameworks/base/core/java/android/app/DemoManager.java

    package android.app;
    
    import android.content.Context;
    import android.os.RemoteException;
    import android.util.Slog;
    
    public class DemoManager {
        Context mContext;
        IDemoManager mService;
    
        public DemoManager(Context context, IDemoManager service) {
            mContext = context;
            mService = service;
        }
    
        public int getCpuTemperature() {
            if (mService != null) {
                try {
                    return mService.getCpuTemperature();
                } catch (RemoteException e) {
                    Slog.e("Demo", "RemoteException " + e);
                }
            }
            return -1;
        }
    }
    
  4. 添加aidl到Makefile src

    frameworks/base/Android.mk

    LOCAL_SRC_FILES += \
        core/java/android/app/IDemoManager.aidl \
    
  5. 添加DEMO_SERVICE常量

    frameworks/base/core/java/android/content/Context.java

    public static final String DEMO_SERVICE = "demo";
    
  6. 注册系统服务

    frameworks/base/core/java/android/app/SystemServiceRegistry.java

    registerService(Context.ORISLINK_SERVICE, DemoManager.class,
        new CachedServiceFetcher<DemoManager>() {
            @Override
            public DemoManager createService(ContextImpl ctx) {
                IBinder b = ServiceManager.getService(Context.DEMO_SERVICE);
                return new DemoManager(ctx, IDemoManager.Stub.asInterface(b));
    }});
    
  7. 开机启动服务

    frameworks/base/services/java/com/android/server/SystemServer.java

    try {
        ServiceManager.addService(Context.DEMO_SERVICE, new DemoManagerService(context));
    } catch (Throwable e) {
        Slog.e("Demo", "Failed to start Demo Service " + e);
    }
    
  8. 编译源码,因为添加了接口,所以需要

    make update-api
    

    更新接口。然后再整编刷机。

  9. service list 查看服务,不存在,这是因为selinux权限没加。

  10. 添加sepolicy权限

device/qcom/sepolicy/msm8937/service.te

type demo_service, system_api_service, system_server_service, service_manager_type;

device/qcom/sepolicy/msm8937/service_contexts

demo  u:object_r:demo_service:s0
  1. 重新编译代码,使用下面测试代码验证

    import android.app.DemoManager;
    
    DemoManager om = (DemoManager) getSystemService(Context.DEMO_SERVICE);
    Log.d(TAG, "Current temperature is " + om.getCpuTemperature());
    

    最终log打印出100,服务添加完成。

[Android][Framework] 添加系统服务

全文结束