init.rc文件里面启动c++程序,通过jni调用java实现
功能:手机开机后要写个标志位。
已有实现,就是收到开机广播后,启动服务读取bp中的标志位(java代码需要等待ril准备好),
并把这个标志位写入到ap中(java代码调用c++)。
后来遇到的问题:实际应用中发现,接收开机广播等待的时间更长,需要提前写入ap时间。
解决方案:
在init.rc文件里面启动c++程序,通过jni调用java实现。
精简代码如下:
C++程序代码:
#define LOG_TAG "testmain" #define LOG_NDEBUG 0 #include <dlfcn.h> #include <cutils/log.h> #include <utils/Log.h> #include <jni.h> using namespace android; void wirtePsCaliValToKernel(); int main (int argc, char * argv[]){ ALOGI("start c"); wirtePsCaliValToKernel(); ALOGI("start c end"); return 0; } void wirtePsCaliValToKernel() { JavaVM* vm; JNIEnv* env; // start a VM JavaVMInitArgs args; JavaVMOption opt; opt.optionString = "-agentlib:jdwp=transport=dt_android_adb,suspend=n,server=y"; args.version = JNI_VERSION_1_4; args.options = &opt; args.nOptions = 1; args.ignoreUnrecognized = JNI_FALSE; void* libdvm_dso = dlopen("libdvm.so", RTLD_NOW); ALOGE_IF(!libdvm_dso, "DdmConnection: %s", dlerror()); void* libandroid_runtime_dso = dlopen("libandroid_runtime.so", RTLD_NOW); ALOGE_IF(!libandroid_runtime_dso, "DdmConnection: %s", dlerror()); if (!libdvm_dso || !libandroid_runtime_dso) { goto error; } jint (*JNI_CreateJavaVM)(JavaVM** p_vm, JNIEnv** p_env, void* vm_args); JNI_CreateJavaVM = (typeof JNI_CreateJavaVM)dlsym(libdvm_dso, "JNI_CreateJavaVM"); ALOGE_IF(!JNI_CreateJavaVM, "DdmConnection: %s", dlerror()); jint (*registerNatives)(JNIEnv* env, jclass clazz); registerNatives = (typeof registerNatives)dlsym(libandroid_runtime_dso, "Java_com_android_internal_util_WithFramework_registerNatives"); ALOGE_IF(!registerNatives, "DdmConnection: %s", dlerror()); if (!JNI_CreateJavaVM || !registerNatives) { goto error; } if (JNI_CreateJavaVM(&vm, &env, &args) == 0) { jclass startClass; jmethodID readPsMeth; // register native code if (registerNatives(env, 0) == 0) { startClass = env->FindClass("android/hardware/Camera"); if (startClass) { ALOGI(" startclass is ok"); //readPsMeth = env->GetStaticMethodID(startClass, "getCurrentFocusPosition", "(I)V"); readPsMeth = env->GetMethodID(startClass, "getCurrentFocusPosition", "()I"); int result = -1; if (readPsMeth) { ALOGI("readPsMeth is ok, result = %d ", result); result = env->CallStaticIntMethod(startClass, readPsMeth); ALOGI("readPsMeth is ok end, result = %d ", result); }else{ ALOGE("-->> readPsMeth is fail"); } }else{ ALOGE("startclass is fail"); } } } return; error: if (libandroid_runtime_dso) { dlclose(libandroid_runtime_dso); } if (libdvm_dso) { dlclose(libdvm_dso); } }
LOCAL_PATH:= $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE:= testmain LOCAL_SRC_FILES:= testmain.cpp LOCAL_C_INCLUDES := LOCAL_MODULE_TAGS := optional eng LOCAL_SHARED_LIBRARIES += libcutils libutils liblog libandroid_runtime libnativehelper libdl include $(BUILD_EXECUTABLE)
init.rc修改:
class 值为main时才能开机自动启动
service testmain /system/bin/testmain class main user root oneshot
end
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