Android输入法IMMS服务启动流程(1)（服务注册）

前言

近期，在公司负责了安全键盘的需求，特意梳理了下Android 输入法相关的流程，以便对整个输入系统有一个整体的认识

基于Android 9.x

目录

1 SystemServer.startOtherServices
2 SystemServiceManager.startService

输入法服务注册过程

输入法服务启动和注册.png

SystemServer.startOtherServices

        if (mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL) {
            traceBeginAndSlog("StartInputMethodManagerLifecycle");
            mSystemServiceManager.startService(InputMethodManagerService.Lifecycle.class);
            traceEnd();
        }

传递的是InputMethodManagerService.Lifecycle.class；Lifecycle是一个SystemService对象

SystemServiceManager.startService

 @SuppressWarnings("unchecked")
    public <T extends SystemService> T startService(Class<T> serviceClass) {
        try {
            final String name = serviceClass.getName();
            Slog.i(TAG, "Starting " + name);
            Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "StartService " + name);

            // Create the service.
            if (!SystemService.class.isAssignableFrom(serviceClass)) {
                throw new RuntimeException("Failed to create " + name
                        + ": service must extend " + SystemService.class.getName());
            }
            final T service;
            try {
                //初始化 new Lifecycle(mContext)
                Constructor<T> constructor = serviceClass.getConstructor(Context.class);
                service = constructor.newInstance(mContext);
            } catch (InstantiationException ex) {
                throw new RuntimeException("Failed to create service " + name
                        + ": service could not be instantiated", ex);
            } catch (IllegalAccessException ex) {
                throw new RuntimeException("Failed to create service " + name
                        + ": service must have a public constructor with a Context argument", ex);
            } catch (NoSuchMethodException ex) {
                throw new RuntimeException("Failed to create service " + name
                        + ": service must have a public constructor with a Context argument", ex);
            } catch (InvocationTargetException ex) {
                throw new RuntimeException("Failed to create service " + name
                        + ": service constructor threw an exception", ex);
            }

            startService(service);
            return service;
        } finally {
            Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
        }
    }


    public void startService(@NonNull final SystemService service) {
        // Register it.
        //添加到本地ArrayList<SystemService>数组中
        mServices.add(service);
        // Start it.
        long time = SystemClock.elapsedRealtime();
        try {
            //调用Lifecycle的onStart方法
            service.onStart();
        } catch (RuntimeException ex) {
            throw new RuntimeException("Failed to start service " + service.getClass().getName()
                    + ": onStart threw an exception", ex);
        }
        warnIfTooLong(SystemClock.elapsedRealtime() - time, service, "onStart");
    }

new Lifecycle

        public Lifecycle(Context context) {
            super(context);
            mService = new InputMethodManagerService(context);
        }

Lifecycle.onStart()

       @Override
        public void onStart() {
            //注册本地服务，供system_server使用
            LocalServices.addService(InputMethodManagerInternal.class,
                    new LocalServiceImpl(mService.mHandler));
            //通过ServiceManager.addService注册服务，供应用层使用
            publishBinderService(Context.INPUT_METHOD_SERVICE, mService);
        }

下一章
Android输入法(5),IMMS服务启动流程(systemRunning)