Android 添加一个自己的系统服务SystemService

Android 系统服务（System Services）是 Android 操作系统的核心组件，运行在系统层面，为应用程序提供底层硬件访问、系统资源管理以及跨应用功能支持。这些服务在后台持续运行，由系统进程（如 system_server）管理，通过模块化设计实现高效的系统控制。常见的AMS，PMS，WMS都属于系统服务。

• ActivityManagerService (AMS)：管理应用生命周期（启动、切换、销毁 Activity）及任务栈。
• PackageManagerService (PMS)：处理应用安装、卸载、权限验证及 APK 解析。
• WindowManagerService (WMS)：控制窗口布局、触摸事件分发及屏幕绘制。

记录一下从app到jni创建系统服务和使用的过程。

1. 编写aidl

frameworks/base/core/java/android/app/mhservice/IDemoService.aidlpackage android.app.demoservice;interface IDemoService {boolean isInfraredOpen();void setInfraredEnabled(boolean isEnabled);boolean setLedColor(int color, boolean open);}

• 添加编译aidl

frameworks/base/Android.mk@@ -559,6 +559,9 @@ LOCAL_SRC_FILES += \core/java/android/service/quicksettings/IQSService.aidl \core/java/android/service/quicksettings/IQSTileService.aidl \+LOCAL_SRC_FILES += \
+    core/java/android/app/demoservice/IDemoService.aidl \

2. 编写Service

frameworks/base/services/core/java/com/android/server/demoservice/DemoService.javapackage com.android.server.demoservice;import android.app.demoservice.IDemoService;
import android.content.Context;public class DemoService extends IDemoService.Stub {private Context mContext;private static native boolean nativeGetInfraredStatus();private static native boolean nativeSetInfraredEnabled(boolean enable);private static native boolean nativeSetLedColor(int color, boolean open);public DemoService(Context context) {mContext = context;}public boolean isInfraredOpen() {return nativeGetInfraredStatus();}public void setInfraredEnabled(boolean enable) {nativeSetInfraredEnabled(enable);}public boolean setLedColor(int color, boolean open) {return nativeSetLedColor(color, open); }
}

3. 编写Manager

• 先在Context中定义Service 名称

frameworks/base/core/java/android/content/Context.java@@ -3373,6 +3373,8 @@ public abstract class Context {*/public static final String CONNECTIVITY_SERVICE = "connectivity";+    public static final String DEMO_SERVICE = "mhdemo";//mh@/*** Use with {@link #getSystemService} to retrieve a* {@link android.net.IpSecManager} for encrypting Sockets or Networks with

frameworks/base/core/java/android/app/demoservice/DemoManager.javapackage android.app.demoservice;import android.app.demoservice.IDemoService;
import android.content.Context;
import android.os.ServiceManager;
import android.util.Log;public class DemoManager {private String TAG = "DemoManager";private Context mContext;private IDemoService mService;public DemoManager(Context context) {mContext = context;mService = IDemoService.Stub.asInterface(ServiceManager.getService(Context.DEMO_SERVICE));}public boolean isInfraredOpen() {try {return mService.isInfraredOpen();} catch (Exception e) {e.printStackTrace();}return false;}public void setInfraredEnabled(boolean enable) {try {mService.setInfraredEnabled(enable); } catch (Exception e) {e.printStackTrace(); }}public boolean setLedColor(int color, boolean open) {try {return mService.setLedColor(color, open); } catch (Exception e) {e.printStackTrace();} return false;}}

4. 注册Service

frameworks/base/core/java/android/app/SystemServiceRegistry.javaimport android.app.timezone.RulesManager;
import android.app.trust.TrustManager;
import android.app.usage.IStorageStatsManager;
@@ -157,6 +158,8 @@ import java.lang.reflect.Method;import java.util.HashMap;
//mh@start import
import android.app.demoservice.DemoManager;
//mh@end@@ -923,6 +926,13 @@ public final class SystemServiceRegistry {return new RulesManager(ctx.getOuterContext());}});
+        //mh@start registerService
+        registerService(Context.DEMO_SERVICE, DemoManager.class, new CachedServiceFetcher<MhWorkManager>() {
+            @Override
+            public DemoManager createService(ContextImpl ctx) {
+                return new DemoManager(ctx.getOuterContext());
+            }
+        });
+        //mh@end/// M: Register mtk service@{sMtkServiceRegistryClass = regMtkService();setMtkSystemServiceName();

frameworks/base/services/java/com/android/server/SystemServer.java@@ -128,6 +128,8 @@ import java.util.concurrent.Future;import static android.view.Display.DEFAULT_DISPLAY;+import com.android.server.demoservice.DemoService;public final class SystemServer {private static final String TAG = "SystemServer";@@ -913,6 +915,10 @@ public final class SystemServer {traceBeginAndSlog("PinnerService");mSystemServiceManager.startService(PinnerService.class);traceEnd();+             //mh@start
+            traceBeginAndSlog("DemoService");
+            ServiceManager.addService(Context.DEMO_SERVICE, new DemoService(context));
+            traceEnd();
+            //mh@end} catch (RuntimeException e) {Slog.e("System", "******************************************");Slog.e("System", "************ Failure starting core service", e);

5. 编写jni

frameworks/base/services/core/jni/com_android_server_demoservice_DemoService.cpp#define LOG_TAG "DemoService-JNI"#include "JNIHelp.h"
#include "jni.h"
#include <android_runtime/AndroidRuntime.h>
#include <utils/misc.h>
#include <utils/Log.h>
#include <stdio.h>namespace android {#define IR_LED              "/proc/uihealth.dsj.v9/ir_led_en_set"
#define LASER_LAMP          "/proc/uihealth.dsj.v9/laser_lamp_en_set"
#define LED_BLUE            "/proc/uihealth.dsj.v9/led_rgb1_set"
#define LED_GREEN           "/proc/uihealth.dsj.v9/led_rgb2_set"
#define LED_RED             "/proc/uihealth.dsj.v9/led_rgb3_set"
#define LED_STROBEBLUE      "/proc/uihealth.dsj.v9/isink_led_set"
#define LED_STROBERED       "/proc/uihealth.dsj.v9/led_red_set"static jboolean nativeGetInfraredStatus(JNIEnv* env, jclass clazz) {int fd;int ret;int cur = 0;char buf[8];fd = open(IR_LED, O_RDONLY);if(fd < 0) {ALOGE("open %s fail",  IR_LED);return false;} else {memset(buf, 0, sizeof(buf));ret = read(fd, buf, sizeof(buf));if(ret <= 0) {ALOGE("read failed, ret=%d", ret);cur = 0;} else {cur = atoi(buf);}}close(fd);return cur != 0;
}static jboolean nativeSetInfraredEnabled(JNIEnv* env, jclass clazz, jboolean enabled) {int fd;int ret;char buf[8];fd = open(IR_LED, O_RDWR);if(fd < 0){ALOGE("open %s failed!", IR_LED);return false;}memset(buf, 0, sizeof(buf));snprintf(buf, sizeof(buf), "%d", enabled);ret = write(fd, buf, strlen(buf));close(fd);return true;
}static jboolean nativeSetLedColor(JNIEnv* env, jclass clazz, jint color, jboolean enable) {int fd;int ret;char buf[8];char *ledn = LED_BLUE;switch (color){case 1://blueledn = LED_BLUE;break;case 2://greenledn = LED_GREEN;break;case 3://redledn = LED_RED;break;}fd = open(ledn, O_RDWR);if(fd < 0){ALOGE("open %s failed!", ledn);return false;}memset(buf, 0, sizeof(buf));snprintf(buf, sizeof(buf), "%d", enable);ret = write(fd, buf, strlen(buf));close(fd);return true;
}static const JNINativeMethod method_table[] = {{"nativeGetInfraredStatus", "()Z", (void *)nativeGetInfraredStatus},{"nativeSetInfraredEnabled", "(Z)Z", (void *)nativeSetInfraredEnabled},{"nativeSetLedColor", "(IZ)Z", (void *)nativeSetLedColor},
};int register_android_server_demoservice_DemoService(JNIEnv *env) 
{return jniRegisterNativeMethods(env, "com/android/server/demoservice/DemoService", method_table, NELEM(method_table));
}}

• 注册jni

frameworks/base/services/core/jni/onload.cpp@@ -52,6 +52,7 @@ int register_android_server_HardwarePropertiesManagerService(JNIEnv* env);
int register_android_server_SyntheticPasswordManager(JNIEnv* env);
int register_android_server_GraphicsStatsService(JNIEnv* env);
int register_android_hardware_display_DisplayViewport(JNIEnv* env);
+int register_android_server_demoservice_DemoService(JNIEnv* env);
};using namespace android;
@@ -98,6 +99,7 @@ extern "C" jint JNI_OnLoad(JavaVM* vm, void* /* reserved */)register_android_server_SyntheticPasswordManager(env);register_android_server_GraphicsStatsService(env);register_android_hardware_display_DisplayViewport(env);
+    register_android_server_demoservice_DemoService(env);return JNI_VERSION_1_4;
}

• 添加编译jni

frameworks/base/services/core/jni/Android.mk@@ -40,6 +40,7 @@ LOCAL_SRC_FILES += \$(LOCAL_REL_DIR)/com_android_server_VibratorService.cpp \$(LOCAL_REL_DIR)/com_android_server_PersistentDataBlockService.cpp \$(LOCAL_REL_DIR)/com_android_server_GraphicsStatsService.cpp \
+    $(LOCAL_REL_DIR)/com_android_server_demoservice_DemoWorkService.cpp \

6. App调用

使用aidl方式，或者源码编译出framework.jar给app引用。参考链接: 引用framework.jar